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REVIEW The zebrafish subcortical social brain as a model for studying social behavior disorders Yijie Geng and Randall T. Peterson* ABSTRACT Social behaviors are essential for the survival and reproduction of social species. Many, if not most, neuropsychiatric disorders in humans are either associated with underlying social deficits or are accompanied by social dysfunctions. Traditionally, rodent models have been used to model these behavioral impairments. However, rodent assays are often difficult to scale up and adapt to high- throughput formats, which severely limits their use for systems-level science. In recent years, an increasing number of studies have used zebrafish (Danio rerio) as a model system to study social behavior. These studies have demonstrated clear potential in overcoming some of the limitations of rodent models. In this Review, we explore the evolutionary conservation of a subcortical social brain between teleosts and mammals as the biological basis for using zebrafish to model human social behavior disorders, while summarizing relevant experimental tools and assays. We then discuss the recent advances gleaned from zebrafish social behavior assays, the applications of these assays to studying related disorders, and the opportunities and challenges that lie ahead. KEY WORDS: Autism, Phylogenetic conservation, Model organism, Social deficit, Neuropsychiatric disorders, Behavioral assay Introduction Social behavior defined as beneficial interaction between individuals in the same species is essential for the survival and reproduction of social species, including humans and many other vertebrates. Social behavior involves specific behaviors such as conspecific preference, social communication, aggression and mating. Many, if not most, neuropsychiatric disorders are related to underlying social defects or are accompanied by social dysfunctions. These include autism, which is associated with deficits in processing social cues, and Williams syndrome, which is characterized by an abnormally high enthusiasm for interacting with strangers. Other disorders that are not primarily social (e.g. schizophrenia and depression) may still interfere with normal social functioning. Therefore, developing and studying animal models with social deficits has far-reaching implications for many neuropsychiatric diseases, and studying these behavioral aspects requires developing specific behavioral assays. Rodents are traditionally used to model disorders associated with social deficits. As highly social species, rodents possess many complex social behavior traits that mimic human behaviors. Additionally, researchers have established sophisticated protocols for studying these behaviors in rodents (Hanell and Marklund, 2014). These benefits make the rodents the current go tomodels for studying disorders associated with social deficits. However, rodent models are not without drawbacks. They are expensive and labor intensive. They are predominantly nocturnal and highly sensitive to environmental disturbances such as light, sound, temperature changes and odors. Furthermore, they have not been very amenable to scalable or high-throughput assays. These drawbacks pose a limit to the broader application of these models in disease research. In recent years, the zebrafish has rapidly become an attractive model for studying behavioral disorders. Adult colonies can be efficiently maintained at high density. Zebrafish give birth to large clutch sizes (>100 eggs per female for each round of breeding) and provide ample offspring for experimental manipulations. The embryos are small (0.7 mm in diameter) and develop ex utero with no special supplementations needed except for water during the first week of development, enabling easily scalable embryonic experimental perturbations. The transparent nature of zebrafish embryos during early development also facilitates imaging and analysis of developmental events. Recent advances in genome- editing technologies such as CRISPR can be applied to zebrafish embryos (Hwang et al., 2013). Unlike rodents, zebrafish are diurnal and can perform behavioral tasks under a normal light setting. Because they remain submerged in water during behavioral tests, zebrafish are not easily affected by minor environmental interferences such as weak sounds and smells. In this Review, we first discuss the neuroanatomical and neurophysiological evidence supporting the use of zebrafish to model human social behavior disorders (see Box 1; Figs 1, 2). We then describe the established experimental methods for studying social behavior deficits and examples of using these assays to model related human disorders. Finally, we explore relevant emerging technological advances and the opportunities and challenges that lie ahead in applying these technologies to social disorder modeling using zebrafish. Zebrafish assays for studying social behavior and deficits There are typically two approaches to modeling a behavioral disorder: by using an endophenotype (see Box 2 for a glossary of terms) assay or a behavioral assay. In this Review, we focus primarily on the behavioral approach. As larval zebrafish develop into adults, their behavior becomes increasingly complex. This is particularly pronounced for socially relevant behaviors. In this section, we briefly review several stereotypical social behaviors in zebrafish and discuss recent advances in developing assay platforms for studying these behaviors. We begin by describing assay setups for specific aspects of social behaviors using traditional and new experimental Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, 30 S. 2000 East, Salt Lake City, UT 84112, USA. *Author for correspondence ([email protected]) R.T.P., 0000-0002-4582-4690 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed. 1 © 2019. Published by The Company of Biologists Ltd | Disease Models & Mechanisms (2019) 12, dmm039446. doi:10.1242/dmm.039446 Disease Models & Mechanisms

The zebrafish subcortical social brain as a model for ... · The zebrafish subcortical social brain as a model for studying social behavior disorders Yijie Geng and Randall T. Peterson*

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REVIEW

The zebrafish subcortical social brain as a model for studyingsocial behavior disordersYijie Geng and Randall T. Peterson*

ABSTRACTSocial behaviors are essential for the survival and reproduction ofsocial species. Many, if not most, neuropsychiatric disorders inhumans are either associated with underlying social deficits or areaccompanied by social dysfunctions. Traditionally, rodent modelshave been used to model these behavioral impairments. However,rodent assays are often difficult to scale up and adapt to high-throughput formats, which severely limits their use for systems-levelscience. In recent years, an increasing number of studies have usedzebrafish (Danio rerio) as a model system to study social behavior.These studies have demonstrated clear potential in overcoming someof the limitations of rodent models. In this Review, we explore theevolutionary conservation of a subcortical social brain betweenteleosts and mammals as the biological basis for using zebrafish tomodel human social behavior disorders, while summarizing relevantexperimental tools and assays. We then discuss the recent advancesgleaned from zebrafish social behavior assays, the applications ofthese assays to studying related disorders, and the opportunities andchallenges that lie ahead.

KEY WORDS: Autism, Phylogenetic conservation, Model organism,Social deficit, Neuropsychiatric disorders, Behavioral assay

IntroductionSocial behavior – defined as beneficial interaction betweenindividuals in the same species – is essential for the survival andreproduction of social species, including humans and many othervertebrates. Social behavior involves specific behaviors such asconspecific preference, social communication, aggression andmating. Many, if not most, neuropsychiatric disorders are relatedto underlying social defects or are accompanied by socialdysfunctions. These include autism, which is associated withdeficits in processing social cues, andWilliam’s syndrome, which ischaracterized by an abnormally high enthusiasm for interacting withstrangers. Other disorders that are not primarily social (e.g.schizophrenia and depression) may still interfere with normalsocial functioning. Therefore, developing and studying animalmodels with social deficits has far-reaching implications for manyneuropsychiatric diseases, and studying these behavioral aspectsrequires developing specific behavioral assays.Rodents are traditionally used to model disorders associated with

social deficits. As highly social species, rodents possess many

complex social behavior traits that mimic human behaviors.Additionally, researchers have established sophisticated protocolsfor studying these behaviors in rodents (Hanell and Marklund,2014). These benefits make the rodents the current ‘go to’ modelsfor studying disorders associated with social deficits. However,rodent models are not without drawbacks. They are expensive andlabor intensive. They are predominantly nocturnal and highlysensitive to environmental disturbances such as light, sound,temperature changes and odors. Furthermore, they have not beenvery amenable to scalable or high-throughput assays. Thesedrawbacks pose a limit to the broader application of these modelsin disease research.

In recent years, the zebrafish has rapidly become an attractivemodel for studying behavioral disorders. Adult colonies can beefficiently maintained at high density. Zebrafish give birth to largeclutch sizes (>100 eggs per female for each round of breeding) andprovide ample offspring for experimental manipulations. Theembryos are small (∼0.7 mm in diameter) and develop ex uterowith no special supplementations needed except for water duringthe first week of development, enabling easily scalable embryonicexperimental perturbations. The transparent nature of zebrafishembryos during early development also facilitates imaging andanalysis of developmental events. Recent advances in genome-editing technologies such as CRISPR can be applied to zebrafishembryos (Hwang et al., 2013). Unlike rodents, zebrafish are diurnaland can perform behavioral tasks under a normal light setting.Because they remain submerged in water during behavioral tests,zebrafish are not easily affected by minor environmentalinterferences such as weak sounds and smells.

In this Review, we first discuss the neuroanatomical andneurophysiological evidence supporting the use of zebrafish tomodel human social behavior disorders (see Box 1; Figs 1, 2). Wethen describe the established experimental methods for studyingsocial behavior deficits and examples of using these assays to modelrelated human disorders. Finally, we explore relevant emergingtechnological advances and the opportunities and challenges that lieahead in applying these technologies to social disorder modelingusing zebrafish.

Zebrafish assays for studying social behavior and deficitsThere are typically two approaches to modeling a behavioraldisorder: by using an endophenotype (see Box 2 for a glossary ofterms) assay or a behavioral assay. In this Review, we focusprimarily on the behavioral approach.

As larval zebrafish develop into adults, their behavior becomesincreasingly complex. This is particularly pronounced for sociallyrelevant behaviors. In this section, we briefly review severalstereotypical social behaviors in zebrafish and discuss recentadvances in developing assay platforms for studying thesebehaviors. We begin by describing assay setups for specificaspects of social behaviors using traditional and new experimental

Department of Pharmacology and Toxicology, College of Pharmacy, University ofUtah, 30 S. 2000 East, Salt Lake City, UT 84112, USA.

*Author for correspondence ([email protected])

R.T.P., 0000-0002-4582-4690

This is an Open Access article distributed under the terms of the Creative Commons AttributionLicense (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use,distribution and reproduction in any medium provided that the original work is properly attributed.

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methods. We then discuss emerging technologies for socialbehavior analysis that will help improve the robustness,consistency and resolution of the current assay methods,including computer vision, machine learning, computationalmodeling, robotics, and virtual reality (VR) technologies.

Social preference assaySocial preference behavior, or the innate tendency of an animal toobserve, mimic and approach a conspecific, is well conservedamong social vertebrate species. Often emerging early duringontogeny (Fantz, 1963), this simple and perhaps primitive form ofsocial behavior forms a necessary foundation for the later, higher-order social functions such as shoaling, schooling and othercomplex social interactions. This behavior is routinely tested inrodents using a three-chamber social preference assay.To study this behavior during development, it is desirable to

design experimental systems that can pinpoint its earliestemergence. Hinz and de Polavieja (2017) discovered thatzebrafish larvae start to show attraction toward a conspecific asearly as 6-7 days post-fertilization (dpf). Although weak at thisstage, the attraction quickly gets stronger each day duringdevelopment. An important note for the experimental setup is thatearly larval zebrafish are also attracted to borders such as the wall ofa Petri dish. Thus, to detect weak social attractions at the early

developmental stage, a testing chamber with a deep center andgradually shallower edge may be used to counter this ‘borderattraction’ by deterring the larvae from the border with shallowwater.

Dreosti et al. adopted a design not unlike the three-chambersocial preference assay for rodents and adult zebrafish (Dreostiet al., 2015): transparent windows divided a U-shaped test arenainto three compartments, including a middle test compartmentand two stimulus compartments (Fig. 3A). A test subject is placedinside the test compartment, and age-matched social stimulusfish are placed inside one of the two stimulus compartments, whilethe third compartment remains empty and thus stimulus free.The social preference of a test subject is quantified as the time itspends near the social stimulus fish. Two-week-old larvaeexhibited a weak social preference, whereas, by 3 weeks, thispreference behavior became highly robust (Fig. 3B). This systemsetup is simple to implement and does not require simultaneoustracking of more than one animal, but limits the test subject’sinput to visual cues, and prevents physical interactions betweenthe fish.

Social preference behavior of adult fish is typically tested inlarger three-compartmented tanks. Zebrafish of the same ordifferent (Engeszer et al., 2004) strains, animated images of fish(Gerlai, 2017), 3D-printed fish models (Bartolini et al., 2016) or

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Fig. 1. Previous theoretical models of the social brain. Brainstructures that constitute previous models of social brainnetworks, illustrated in a mammalian brain from a lateral view.(A) The social behavior network (SBN) (Newman, 1999). (B)The social decision-making (SDM) network (O’Connell andHofmann, 2011b), composed of the SBN and the mesolimbicreward system (MRS). AH, anterior hypothalamus; BLA,basolateral amygdala; BNSTm, medial bed nucleus of the striaterminalis; HIP, hippocampus; LS, lateral septum; MPOA,medial preoptic area; NAc, nucleus accumbens; PAG,periaqueductal gray; STR, striatum; VMH, ventromedialhypothalamus; VP, ventral pallidum; VTA, ventral tegmentalarea.

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robotically controlled biomimetic zebrafish (Kopman et al., 2013;Ruberto et al., 2016, 2017) can be used as social stimuli.Researchers can place different stimuli in the two testcompartments to assess preference. For example, wild-type (WT)fish typically prefer a WT conspecific over a nacre (Box 2) fish(Braida et al., 2012). Interestingly, this tendency is reversed by

oxytocin, vasopressin, and amphetamine derivatives (Braida et al.,2012; Busnelli et al., 2016; Ponzoni et al., 2016). A WT test fishremembers a familiar fish from this assay for at least 24 h, andprefers to interact with an unfamiliar fish over a familiar one(Madeira and Oliveira, 2017). A two-compartment design has alsobeen implemented for testing adult (Liu et al., 2018a) and juvenile(Patowary et al., 2019) fish, with social preference assessed by theproximity of a test subject to the social stimulus fish.

As will be demonstrated in examples in later sections, a three- ortwo-chamber social preference assay is frequently used to assesssocial preference of individuals subjected to different experimentaltreatments. A major benefit of this approach may be that testsubjects are examined individually, as opposed to in groups as willbe described in shoaling and schooling assays, such that the degreeof social preference for each test subject can be easily quantified.A three-chamber assay setup also enables one to assess preferencebetween two types of stimuli, such as two different fishstrains. However, restrictions in sensory inputs and physicalinteractions limit the assay’s ability to evaluate more complexmodes of social behaviors.

ShoalingGroups of zebrafish naturally form compact aggregations, abehavior called shoaling, which emerges as early as 15 dpf (Hinzand de Polavieja, 2017). Benefits of shoaling may include betterdetection of and defense against predators, enhanced foraging andincreased mating choices (Krause and Ruxton, 2002). While moststudies choose the number of fish to be tested in a shoaling assayarbitrarily, a number that balances between minimizing animalusage and reducing variability may be estimated using a methodbased on Shannon entropy (Box 2) (Eguiraun et al., 2018).

Traditionally, shoaling is examined by two-dimensional (2D)video recording and analysis. A number of freely availablecomputer vision programs and commercial software have beendeveloped for detecting this behavior in grouped zebrafish(reviewed in Franco-Restrepo et al., 2019). Methods forquantifying shoaling behavior in a 2D recording typically don’trequire the fish to be individually distinguishable. Measurements ofinter-individual distance and nearest-neighbor distance arecommonly used to quantify the tightness of a shoal (Miller andGerlai, 2007). Alternatively, analyzing a shoal by Delaunaytriangulation (Box 2) can provide a unique measurement for therelative positions of each fish in a shoal configuration, as well as itsoverall tightness (Xiao et al., 2015). The trajectory of a shoal can beobtained by tracking its centroid (Eguiraun et al., 2018).

Because fish behave in a three-dimensional (3D) space, 3Drecording and analysis systems are being developed using mirrors(Maaswinkel et al., 2013b; Audira et al., 2018b), multiple cameras(Macrì et al., 2017; Qian and Chen, 2017; Bishop et al., 2016; Al-Jubouri et al., 2017;Wang et al., 2017b; Butail and Paley, 2012) or asingle camera with depth-sensing capability (Kuroda, 2018) toassess shoaling more accurately. The complex 3D trajectories of fishhave been modeled using a long short-term memory (Box 2)network (Wang et al., 2017b).

WT zebrafish form tight shoals. As will be discussed in latersections, experimental perturbations can lead to changes in shoalcohesion. A reduction in shoal cohesion is often interpreted asdecreased social interactions among members of the group.However, simple measurements of aggregation cannot fully revealthe complex, interactive and inter-dependent forces betweenindividuals (Katz et al., 2011) or the collective dynamics of agroup (Rosenthal et al., 2015).

Box 1. The ‘subcortical social brain’ and its evolutionaryconservation between zebrafish and mammals

Complex higher-order human social behaviors, such as face recognition,social cognition, perception of social signals, social judgement, socialdecision making and theory of mind, rely substantially on cortical input(Adolphs, 2003). The cerebral cortex is widely considered to be themajorcontroller of these higher-order social behaviors (Adolphs, 2009;Blakemore, 2008, 2012; Frith, 2007). Human studies have identifiedspecific cortical brain regions, such as the medial prefrontal cortex(mPFC) and the posterior superior temporal sulcus (pSTS), thatcontribute to these functions (Adolphs, 2009; Frith, 2007; Blakemore,2008, 2012). This focus on cortical inputs sometimes overlooks thecritical functions that subcortical brain regions play in regulating socialbehavior. In fact, a complex network of subcortical brain regionsassociated with social behavior exists and is highly conserved amongall vertebrates (Newman, 1999; O’Connell and Hofmann, 2011b). Here,we conceptualize a ‘subcortical social brain’ (SSB) based on theoreticalframeworks and recent experimental findings.

Originally suggested for mammals, Newman (1999) proposed a core‘social behavior network’ (SBN) based on evidence from neuroendocrineand behavior studies. The SBN consists of several brain regions as‘nodes’, including the medial amygdala, medial bed nucleus of striaterminalis, lateral septum, preoptic area, anterior hypothalamus,ventromedial hypothalamus and the midbrain periaqueductal gray/central gray (Fig. 1A). In this model, each node responds to a varietyof social stimuli, and all nodes collaboratively respond with a distinctpattern to modulate different behavioral outputs.

O’Connell and Hofmann (2011b) pointed out the importance of themesolimbic reward system (MRS), consisting of the ventral tegmentalarea, nucleus accumbens, basolateral amygdala, striatum, ventralpallidum, hippocampus and several regions overlapping with the SBN,in social behavior. They further argued that the SBN and MRScollectively constitute a larger social decision-making (SDM) network(O’Connell and Hofmann, 2012, 2011b) (Fig. 1B). Finally, theydemonstrated that this network is largely conserved between zebrafishand mammals (O’Connell and Hofmann, 2011a, 2012). Functionalanalysis of immediate early genes after social interaction supports thishypothesized network (Teles et al., 2015).

Recent studies have linked additional subcortical brain regions to socialbehavior, and homologous structures for these socially relevant brainregions, such as the dorsal raphe (Dölen et al., 2013), lateral habenula(Golden et al., 2016) and cerebellum (Carta et al., 2019), are also presentin zebrafish (Yokogawa et al., 2012; Amo et al., 2010; Heap et al., 2013).The anatomical and functional conservation of these SSB componentsare summarized in Table 1 and Fig. 2.

Although many cortical regions in the mammalian brain are also relevantto social behavior by serving executive functions during socialinteractions and have been discussed elsewhere (Adolphs, 2009;Blakemore, 2008, 2012; Frith, 2007), we chose to focus this Review onthe SSB for its relevance to zebrafish social behavior. We argue that itsstrong evolutionary conservation suggests a critical role in supporting thesurvival and reproduction of not only fish, but also other vertebratespecies, including humans. Knowledge acquired from investigating theSSB may therefore provide valuable insights into human social behaviordisorders (Lord et al., 2000).

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SchoolingIn addition to shoaling, a group of zebrafish can ‘school’. Whileshoals are simple aggregations of individual fish, schools are shoalsthat exhibit polarized formations and synchronized motions.Density and group size affect shoal cohesion, but not polarization(Shelton et al., 2015). Acute treatment with alcohol strongly affectsshoal polarization but only modestly inhibits cohesion, whereasnicotine significantly reduces cohesion but modestly affectspolarization (Miller et al., 2013). These differences indicate thatschooling and shoaling are two differentially regulated behaviorsand that assessing both behavioral endpoints together may moreeffectively characterize the effects of experimental treatments. Tanget al. (2018) developed an unsupervised machine learning approachto examine schooling of adult zebrafish. Using this assay, theauthors classified group behavior into distinct stereotypical states ofpolarization, and found that genetic mutations (see later sections fordetails) can alter the proportion of time spent or the tendency totransition between these states. While this approach provides aninnovative way to quantitatively evaluate the propensities of a groupto adopt stereotypical states of schooling, it is limited to detectingstatic patterns of group formation as a whole and cannot revealdynamic interactions among group members.

AggressionAdult male zebrafish fight to establish dominance and hierarchy,and to compete for important resources such as food and mates(Huntingford and Turner, 1987). A simple way to assay aggressivebehavior is by introducing a target for the test subject to attack.

A mirror is often used to allow the test subject to attack its ownreflection (Zabegalov et al., 2019). Alternatively, a dummy fish or avideo recording of another fish can trigger aggression (Way et al.,2015). The number of times a test subject exhibits aggressivebehavior, such as biting and charging, is counted to quantify itslevel of aggressiveness. Although this assay provides a simplemeans to quantify aggression, the lack of physical contact betweenaggressors and targets limits its ability to mimic natural fightingbehaviors. Interestingly, live fish have not been used as targets inthis assay setup. Instead, when two fish interact through atransparent window, their behaviors were typically interpreted associal interaction (such as in a two-compartment social preferenceassay) rather than aggression.

Dyadic fighting assays examine aggression in a more naturalsetting. Although fighting behaviors are highly complex,stereotypical bouts can be repeatedly observed throughout a fight(Teles and Oliveira, 2016b; Zabegalov et al., 2019). Traditionally, ahuman observer monitors the process, manually annotates thesebehavioral bouts and keeps track of the outcomes of a fight (Chouet al., 2016). Alternatively, a recently developed analysis pipelineautomatically annotates stereotypical fighting behavior with sub-second precision (Laan et al., 2018) (Fig. 3C), demonstrating greatpromise in applying unsupervised machine learning methods tostudying complex natural behaviors.

The social hierarchy of a group can be assessed from dyadicfighting outcomes. Changes in social status have been associatedwith an individual’s altered motor activity (Clements et al., 2018),reproductive success (Paull et al., 2010), and other physiological

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Fig. 2. The subcortical social brain (SSB) inzebrafish and mouse. (A) The teleost SSBillustrated from a lateral view. (B) Themammalian(rodent) SSB illustrated from a lateral view. Areaswith the same color mark regions that arehomologous between teleosts and mammals.For regions with different nomenclaturesbetween teleosts and mammals, thecorresponding mammalian nomenclatures areappended after the teleost nomenclature inparentheses. AH, anterior hypothalamus; ATN,anterior tuberal nucleus; BLA, basolateralamygdala; BNSTm, medial bed nucleus of thestria terminalis; CB, cerebellum; Dl, lateral dorsaltelencephalon; Dm, medial dorsaltelencephalon; DR, dorsal raphe; HIP,hippocampus; LHb, lateral habenula; LS, lateralseptum; MeA, medial amygdala; MPOA, medialpreoptic area; NAc, nucleus accumbens; PAG,periaqueductal gray; POA, preoptic area; PT,posterior tuberculum; STR, striatum; Vc, centralventral telencephalon; Vd, dorsal ventraltelencephalon; VHb, ventral habenula; VMH,ventromedial hypothalamus; VP, ventralpallidum; Vs, supracommissural nucleus of theventral telencephalon; VTA, ventral tegmentalarea; VTN, ventral tuberal nucleus; Vv, ventralnucleus of the ventral telencephalon.

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and health consequences (Filby et al., 2010a). Social animals adjusttheir behavior based on their status within a group, a phenomenoncalled social plasticity, which is also studied using aggression assays

(Teles et al., 2016a; Maruska et al., 2019; Guayasamin et al., 2017;Sykes et al., 2018).

An animal can observe interactions between other individuals anduse this information to adjust its own future behavior, a phenomenonnamed ‘social eavesdropping’. A common assay uses a two-chambertest arena divided by a one-way transparent window. An observer fishis placed in the chamber on the see-through side of the window,allowing it to observe the outcome of a fight in the opposing chamberwithout interacting with these fish (Abril-de-Abreu et al., 2015a). Avideo recording of a fight can also be used to train the observer fish(Abril-de-Abreu et al., 2015b). The time the observer fish spends inthe vicinity of the observation window quantifies its attention. Theobserver fish remembers the participants and the outcome of the fightand adjusts its future dominant or submissive behaviors toward theseindividuals accordingly. Attentiveness toward a fight activates geneslinked to neuronal plasticity, memory formation and alertness (Lopeset al., 2015).

As an assay with clearly separated binary outcomes, theaggression assay has been used to examine transcriptional (Malkiet al., 2016; Oliveira et al., 2016) and neurophysiological (Teles andOliveira, 2016a; Pavlidis et al., 2011; Filby et al., 2010b) outcomesof winning or losing a fight. Such effects were also examined in fishwith different social statuses (Sneddon et al., 2011; Larson et al.,2006; Teles et al., 2016b).

MatingHighly stereotypical mating behaviors have been described forzebrafish (Darrow and Harris, 2004), although automated computervision methods remain to be developed for mating behavior analysis.Several reports have created VR mimetics of the fish sailfin molly(Poecilia latipinna) and have used these animated animals to study themating choices of live fish (Gierszewski et al., 2018, 2017; Mülleret al., 2017a), an approach that may be transferrable to zebrafish.Zebrafish imprint visual and olfactory cues at 6 dpf, and use thisphenotypic template to match and avoid mating with its own kin asadults (Gerlach et al., 2008; Hinz et al., 2013). Interestingly, exposureto non-kin cues does not result in successful imprinting (Gerlach et al.,2008), suggesting that additional mechanisms exist that regulate kinrecognition (Biechl et al., 2016; Gerlach et al., 2019).

Social learningZebrafish can learn from their peers. Social learning may helpindividuals in a group acquire public knowledge on resources suchas food and threats such as predators without each individual payingthe costs for learning. Naïve fish can learn an escape route (Lindeyerand Reader, 2010) or to find food (Zala and Määttänen, 2013) froma knowledgeable demonstrator fish. A separate study, however,reported that observer fish were unable to learn how to find food in amaze from demonstrators (Roy and Bhat, 2017). Wild-caughtzebrafish are typically more timid than their domesticatedcounterparts. Wild zebrafish become bolder when exposed todomestic fish, without changing the level of boldness of thedomestic fish, and this change in behavior persists after removal ofthe domesticated fish (Zala et al., 2012).

Tracking individuals in a group using computer visionTo examine group dynamics during behavioral assays in moredetail, researchers have explored methods to track individual fish ina group. This is a difficult task, as zebrafish swim in a 3D space, andindividuals in a group will unavoidably cross over each other ina camera’s view. Conventional solutions focus on derivingalgorithms for predicting the trajectories of each fish. Before each

Box 2. Glossary

Alarm substance: also known as Schreckstoff (startle/shocksubstance); a chemical alarm signal released by injured fish thatinduces fear in conspecifics. A method for extracting zebrafish alarmsubstance can be found in the report by Schirmer et al. (2013).

Bayesian decision theory: a statistical method that calculates thetradeoff between various decisions using Bayesian estimation.

Chemogenetics: the modification of biological macromolecules, suchas proteins, to interact with previously unrecognized ligands. EngineeredG protein-coupled receptors (GPCRs), such as designer receptorexclusively activated by designer drugs (DREADDs) (Armbruster et al.,2007), can be activated by an otherwise inert ligand to modulate theactivity of genetically modified neurons.

Delaunay triangulation: for a given set of discrete points in a plane, aDelaunay triangulation generates a network of triangles between thesepoints,which ensures that nopoint is inside the circumcircle of any triangle.

Endophenotype: an experimentally measurable trait that geneticallysegregates with an illness. Frequently used in psychiatric diseaseresearch to connect higher-order complex behavioral symptoms togenetics.

Fetal alcohol spectrum disorders: a group of conditions, includingphysical and behavioral problems, that can occur in a person prenatallyexposed to alcohol.

Fetal valproate syndrome: a condition that can occur in a person byprenatal exposure to the anti-seizure medication valproic acid (sodiumvalproate).

Immediate early gene: a gene that is activated rapidly but oftentransiently at the transcription level in response to certain stimuli.

Long short-term memory: abbreviated as LSTM; a recurrent neuralnetwork architecture used in deep learning. It is particularly suitable foranalyzing and making predictions for time-series data containing lags ofunknown duration between important events.

Morphant: in zebrafish, gene expression levels can be knocked down atthe early embryonic stage through embryonic injection of morpholinoantisense oligonucleotides. A zebrafish treated with a morpholino totemporarily inhibit expression of a targeted gene is called a morphant.

nacre: a zebrafish genetic mutation (Lister et al., 1999). Homozygousnacremutants lackmelanophores, a type of pigment cell, and are thereforepartially transparent and visually different from wild-type zebrafish.

Optogenetics: an experimental method that uses light to controlactivation and/or inhibition of genetically modified neurons expressinglight-responsive ion channels.

Shannon entropy: also known as ‘information entropy’; provides ameasurement of the predictability of the value of a variable. In Eguiraunet al. (2018), Shannon entropy was used to measure the predictability ofthe trajectory of a shoal’s centroid.

Transfer entropy: a measurement of the amount of directed transfer ofinformation between two random processes. It provides a quantification ofthe cause-and-effect relationships between (possibly) coupled time series.

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crossover, the program calculates the most likely trajectory of eachfish, so that, immediately after the two fish are separated,the algorithm assigns identities to each fish based on how welltheir new trajectories match the predictions. This method frequentlyintroduces errors and unavoidably fails after long periods oftracking.To solve this problem, the de Polavieja lab developed idTracker,

which identifies and tracks individuals using a distinct digitalfingerprint generated for each fish (Pérez-Escudero et al., 2014)(Fig. 4A). Crossover events still interfere with tracking, but only

temporarily, as identities are reassigned after each crossover basedon the fingerprint. Thismethod enables researchers to acquire insightsto previously difficult-to-observe behaviors in a group, such asterritorial behavior. Their recently updated method, idTracker.ai,simultaneously tracks 100 individuals using deep learning with animpressive identification accuracy of greater than 99.9% (Romero-Ferrero et al., 2019). Building on the idTracker approach, severalrecent attempts have achieved multi-individual identification andtracking, with varying degrees of success (Bai et al., 2018; Qianand Chen, 2017; Qian et al., 2016, 2014; Wang et al., 2016a).

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Fig. 3. Examples of zebrafish social behavior assays. (A) The three-chamber social preference assay. Adapted fromDreosti et al. (2015), where it was publishedunder a CC-BY licence. A test subject (TS) is placed inside a U-shaped chamber. Social stimulus (SS) fish are placed inside one of the chambers at the end of theU-shaped arena, separated from the test subject’s chamber bya transparent window. The other end of theU-shaped arena is left emptyas a control stimulus. (B) Three-week-old zebrafish develop a robust social preference. A test subject visits the two compartments randomly if both compartments are empty; if social stimulus fish areintroduced into one compartment, the test subject is attracted to and interacts intensively with the social stimulus fish. Adapted fromDreosti et al. (2015), where it waspublished under a CC-BY licence. Red, movements in the social interaction zone; black, movements in the middle zone; blue, movements in the control zone.(C) Analysis of fighting behavior usingmachine learning. Adapted fromLaanet al. (2018), where itwas published underaCC-BY licence. Imagesare acquired (1) andtwoanimals in the test arenaare tracked individually (2). Fractions of the trackingcoordinates aremanuallyannotated for fightingbehavior (3). This is thenused to traina neural network (4), which automatically detects attacks by generating an attack score for each fish (5). An ethogram is generated based on the attack score (6).

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Computational modeling of collective behaviorsComputational modeling has been applied to studying groupbehaviors of zebrafish and has generated valuable insights intogroup dynamics of fish and other species such as humans (Madirolasand de Polavieja, 2015). Previous methods largely ignored individualbehaviors and focused primarily on examining static features ofcollective behavior at each time point, such as group cohesioncalculated based on the distribution of individuals’ positions, andpolarization, which is assessed by individuals’ orientations. Thislimitation may be attributed to limited understanding of stereotypicmotions and difficulties in continuous tracking of individuals.Although ignoring individual identities allows each fish to betreated as a particle and aids the application of machine learningmethods to characterize group behavior as a whole (Butail et al.,2013b), it inevitably limits further investigations on how individualsmake behavioral decisions in a group.One approach to overcome these limitations is to examine the

behaviors of isolated individuals given different social cues, such asby using a three-chamber social preference setup (Fig. 3A)(Arganda et al., 2012; Porfiri and Ruiz Marín, 2017). Researchershave modeled individual behavioral rules in response to the motionof a social stimulus fish using theoretical frameworks based on the

Bayesian decision theory (Box 2) (Arganda et al., 2012) and transferentropy (Box 2) (Porfiri and Ruiz Marín, 2017). Other studies firstimproved continuous tracking of individuals and thencomputationally modeled pairwise interactions using the optimalcontrol theory (Laan et al., 2017), deep attention networks (Heraset al., 2018), transfer entropy (Butail et al., 2016) and other data-driven methods (Zienkiewicz et al., 2018) to reveal how pairs ofindividuals attract, repulse and align with each other.

Recent studies have applied computational and machine learningmethods tomodel individual stereotypicalmotions ofCaenorhabditiselegans (Stephens et al., 2008; Brown et al., 2013), fruit flies (Bermanet al., 2014), mice (Wiltschko et al., 2015) and zebrafish (Marqueset al., 2018; Mwaffo et al., 2017; Zienkiewicz et al., 2015).Combining individual behavioral modeling with continuousindividual tracking provides an opportunity to investigate groupdynamics and individual decision-making with higher resolution. Inone study, individual motions alternated between acceleration anddeceleration bouts. The kinetics of these bouts could be described bysigmoid and exponential functions, respectively. Individual zebrafishmotions were found to alternate between a ‘passive’ behavioral mode,in which behaviors of an individual are unaffected by other groupmembers, and an ‘active’ mode, in which an individual’s behavior

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Fig. 4. Examples of emerging technologies for social behavior assays and analysis. (A) idTracker for tracking individuals in a group. The raw images ofeach fish were first segmented to identify the body of each fish. Two pixels with intensities i1 and i2 are highlighted, which are separated by a distance, d. An intensitymap is generated for each fish to show how many pairs of pixels are at a certain distance (d) and have a certain sum of intensities (i1+i2). This intensity map isused to identify each individual fish. Adaptedwith permission fromPerez-Escudero et al. (2014). This image is not published under the terms of the CC-BY licence ofthis article. For permission to reuse, please see Perez-Escudero et al. (2014). (B) Avirtual reality (VR) fish that mimics a 23-dpf real fish. Reproduced with permissionfrom Stowers et al. (2017). This image is not published under the terms of the CC-BY licence of this article. For permission to reuse, please see Stowers et al.(2017). (C) A self-propelled robotic fish. Reproduced with permission from Butail et al. (2013a), where it was published under a CC-BY licence.

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adjusts to social input from the group. This framework predictedbehaviors of individuals with high precision (Harpaz et al., 2017).

Virtual realityCollective behaviors such as shoaling are mutual: each individual isdriven by social cues emitted by its shoal mates and at the same timeemits social signals that influence its shoal mates. Owing to theinteractive nature of this closed-loop feedback system, it is difficult todisentangle a social input from the outputs it triggered. VR systemshave the advantage of providing socially relevant inputs in a controlledand isolated manner. A projected virtual object moving in a way thatmimics the characteristic kinetics of zebrafish swim bouts wassufficient to trigger shoaling of juvenile fish. Other previouslyimplicated social cues, such as a fish-like shape or pigmentationpattern, were not required to trigger this behavior (Larsch and Baier,2018). In another example, a virtual zebrafish was created to mimic a23-dpf fish (Stowers et al., 2017) (Fig. 4B). In this interactive VRsystem, the movement trajectory of the virtual zebrafish wasprogrammed to be influenced to varying degrees by the trajectory ofa real fish. When set to be strongly influenced by the real fish, thevirtual fish spent most of the time following the real fish and thusminimally affected the real fish’s typical trajectory.Gradually reducingthe level of social feedback resulted in the virtual fish exerting astronger influence on the trajectory of the real fish, and therefore itseemed to ‘lead’ the real fish. Continued reduction in the degree ofsocial feedback, however, eventually decreased the influence of thevirtual fish on the real fish and led to its failure in leading.

‘Robot zebrafish’Robotically controlled biomimetics have been developed to mimicanimal behaviors and socially interact with animals such as fruitflies (Zabala et al., 2012) and cockroaches (Halloy et al., 2007),providing valuable insights into the social behaviors of thesespecies. Similarly, a number of research groups have developedrobotic fish (Cazenille et al., 2018). These systems are oftencomposed of two parts: a biomimetic fish dummy and a roboticcontrol system. The fish dummies can be directly fixed to a robotarm, indirectly linked to andmoved by a robotic mechanism throughmagnetic coupling, or self-propelled (Butail et al., 2013a) (Fig. 4C),enabling them to ‘swim’ under water. Zebrafish respond to arobotically controlled dummy in a three-compartment socialpreference assay (Kopman et al., 2013; Ruberto et al., 2016,2017). Compared to VR, a major advantage of robotic systems istheir ability to provide physical contact between a biomimetic andan animal. Therefore, other groups have developed robot zebrafishthat can come into physical contact with real zebrafish shoals(Cazenille et al., 2018; Polverino et al., 2012). However, the keyfeatures that allow a biomimetic fish to be socially integrated into agroup of fish are still being debated. While many efforts focused onidentifying socially attractive morphologies such as shape, size andpigmentation patterns for the dummy, other studies argued that arobot’s behavior, such as its trajectories and movement kinetics,exert a greater influence on its ability to socially integrate into ashoal (Cazenille et al., 2018).

Popular assays and their variationsAmong the assays discussed above, the social preference, shoalingand aggression assays may be the most frequently used. Possiblereasons for their popularity may be that they are relatively easy to setup, have intuitive relevance to social behaviors in humans, and havesimple and quantifiable readouts. These assays are commonly usedto assess changes in social behavior induced by disease-relevant

treatments, as discussed further in the next section. Many variationsexist for each assay, including but not limited to dimensions of thetest platforms, numbers of animals used, types of stimulus(particularly for social preference and aggression assays), andquantification criteria and methods. This poses a potential challengefor the field, as the diversity of assays complicates interpretation ofresults and comparison between studies. It is worth noting thatsimilar diversity is also widely present in rodent assays, which arecurrently still considered the gold standard for measuring socialbehavior. Nevertheless, efforts should be made to standardizecurrent behavioral assay formats in zebrafish. Carefully designedexperiments should be performed to evaluate these variations andprovide recommendations for the optimal formats of each assay.

Disease-relevant social-deficit models in zebrafishIn this section, we discuss recent advances in using zebrafish tomodel human social-behavior-related disorders. Although non-behavioral endpoints exist, including anatomical changes andendophenotypes, behavioral assays most directly demonstrate therelevance of these models to actual human behavioral disorders.Therefore, we focus on studies that model these disorders usingsocial behavior assays. We categorize these studies based on thedifferent methods used to induce social deficits.

Genetic modelsTechnologies such as CRISPR, transcription activator-like effectornucleases (TALENs) and zinc-finger nucleases (ZFNs) have beenimplemented in zebrafish to generate genetic models. Forward-genetics methods can also generate mutants through randommutagenesis.

Autism risk genesModulating autism-related genes in zebrafish can induce autism-related phenotypes. However, the endpoints assessed in thesestudies have primarily focused on developmental and physiologicalchanges or other comorbid behavioral symptoms of autism such asanxiety, sleep disorders and seizures. For example, cntnap2knockout induced night-time hyperactivity (Hoffman et al., 2016),and chd8 morphants (Box 2) and mutants developed macrocephaly(Sugathan et al., 2014; Bernier et al., 2014). Researchers havestarted examining social behavior deficits in more recent studies.Knocking out the autism gene shank3b (Durand et al., 2007)induced deficits in shoaling, social preference and kin recognition(Liu et al., 2018a). Zebrafish with mutant sam2, ortholog to thehuman FAM19A2 gene, were found to have shoaling (Choi et al.,2018) and social preference (Ariyasiri et al., 2019) deficits. Thehuman FAM19A2 gene is located in the 12q14.1 locus, home to acopy-number variation (CNV) associated with intellectual disabilityand autism (Autism Genome Project et al., 2007).

Zebrafish also demonstrated its rapid disease-modeling capabilityin a recent study in which a novel autism risk gene, CEP41, wasidentified by whole-exome sequencing. The zebrafish CEP41morphant showed deficits in social preference behavior (Patowaryet al., 2019), providing experimental support for this new autismrisk gene. A CRISPR-based targeted mutagenesis studysystematically evaluated 35 autism and schizophrenia risk genesin an unsupervised machine learning assay for schooling (Tanget al., 2018). Significant behavioral changes were observed in theimmp2l and scn1labmutants; immp2l knockout enhanced shoaling,whereas heterozygous mutation in scn1lab seemed to suppress allevident social interactions between individuals. Their humanortholog, IMMP2L, is associated with Tourette syndrome (Petek

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et al., 2001), and SCN1A is associated with autism (Weiss et al.,2003) and Dravet syndrome (Wolff et al., 2006). Several othermutations also altered shoaling and schooling, but to a lesser degree.

Intellectual-disability risk genesIntellectual disability is often comorbid with autism. Zebrafishknockout of dyrk1aa, an ortholog of the human Down syndromegeneDYRK1A, induced shoaling and social preference impairments(Kim et al., 2017b). Fragile X syndrome is a form of humanintellectual disability caused by a loss-of-function mutation of thefragile X mental retardation 1 (FMR1) gene (Wu et al., 2017).Interestingly, knocking out of zebrafish fmr1 caused precociousdevelopment of shoaling behavior, a phenomenon interpreted as aresult of hyperactivity and increased anxiety (Wu et al., 2017),although such a phenomenon does not seem to be present in humanpatients with fragile X syndrome (Tranfaglia, 2011).

Schizophrenia risk genesThe zebrafish ortholog of the schizophrenia risk gene DISC1induced impaired shoaling response to stress when mutated (Eachuset al., 2017). Acute exposure to alarm substance (Box 2) or osmoticstress increased shoal cohesion in 5-dpf WT fish but not disc1mutants, suggesting its role in the development of thehypothalamic-pituitary-interrenal (HPI) axis, the fish equivalentof the hypothalamic-pituitary-adrenal (HPA) axis. Knocking outadra1aa and adra1ab, the two zebrafish orthologs of humanADRA1A, causes fish to freeze in tight groups for prolonged periodsof time (Tang et al., 2018). Polymorphisms in the promoter regionof the ADRA1A gene have been associated with schizophrenia(Clark et al., 2005), although not without controversies (Huanget al., 2008; Clark et al., 2006). While the freezing behavior found infish is significant, whether or how this deficit translates to humandisease phenotypes may require further investigation.

Other genetic models that cause social deficitsResearchers serendipitously discovered increased aggression in thespiegeldanio strain, an fgfr1at3R705H/t3R705H mutant (Norton et al.,2011), during routine stock maintenance. This mutant showedincreased mirror biting behavior and novel-object exploration,reminiscent of behavioral phenotypes seen in aggression-boldnesssyndrome. However, association of the human FGFR1 withaggression has not been reported.Leptin is generally known as an appetite regulator, but recent

evidence has shown that it also plays roles in behavioral regulation(Morrison, 2009). Knockout of lepa by TALENs resulted in reducedaggression in a mirror-biting assay and reduced shoaling (Audiraet al., 2018a). The authors argue that a dysregulated HPI/HPA axismay be responsible for the social deficit phenotype. In humans, anelevated leptin level has been associated with autism (Ashwoodet al., 2008; Blardi et al., 2010; Raghavan et al., 2018) and Rettsyndrome (Blardi et al., 2007, 2009), whereas a decrease in leptin islinked to schizophrenia and depression (Kraus et al., 2001; Atmacaet al., 2003).

Gene expression modulation modelsChanges in gene expression levels have been associated with socialdisorders. For example, CNV in chromosome region 16p11.2 islinked to autism (Sebat et al., 2007). Overexpression of the 29 genesencompassed by the 16p11.2 CNV in zebrafish identified KCTD13as an inducer of microcephaly (Golzio et al., 2012). Suppression ofthe same gene by morpholino resulted in macrocephaly (Golzioet al., 2012). Zebrafish morphants in several of these genes also

showed deficits in brain-ventricle and midbrain development(Blaker-Lee et al., 2012). Although modulation of geneexpression at the larval or adult stages is also possible usinginducible expression systems (Chiu et al., 2016), this has not beenutilized to establish social-deficit models in zebrafish.

Chemically induced models: embryonic and maternal exposureBoth genes and the environment contribute to the development ofsocial behavior. For example, environmental factors are estimated toaccount for 41% of autism risk (Gaugler et al., 2014). In fact, anumber of environmental toxins, such as bisphenol A (BPA) (Steinet al., 2015), polychlorinated biphenyls (PCBs) (Lyall et al., 2017)and pesticides (von Ehrenstein et al., 2019), have been associatedwith elevated autism risk through epidemiological research, andwere investigated in rodent models (Yu et al., 2011; Jolous-Jamshidiet al., 2010; Lan et al., 2017; Mullen et al., 2012). The zebrafishprovides a powerful model for studying environmental factors thataffect social development, especially given the simplicity ofcompound administration through water immersion. Thissubsection summarizes findings on how chemical exposure priorto or during embryonic development affects social behavior.

Alcohol and other abused drugsAlcohol consumption during pregnancy can lead to fetal alcoholspectrum disorders (FASDs; Box 2). Patients with less-severe FASDcan exhibit social deficits without anatomical changes (Seguin andGerlai, 2018). Zebrafish embryos that were briefly (2 h) exposed tolow levels (up to 1%) of alcohol develop to adults with no grossanatomical changes but show dose-dependent reductions in socialpreference to virtual (Fernandes and Gerlai, 2009) or live (Buske andGerlai, 2011) social stimuli. This effect is likely mediated byimpairments in the dopaminergic and serotoninergic systems(Fernandes et al., 2015; Buske and Gerlai, 2011). Embryonicexposure to another commonly abused drug, ketamine, did notsignificantly alter shoaling behavior (Félix et al., 2017a,b).

Prescription drugsWhen taken during pregnancy, some common prescription drugsmay have side effects or toxicity that affect the development ofsociality in humans. In addition, due to their continuous usage andemission, pharmaceuticals often accumulate faster than they areremoved from the environment and are considered pseudo-persistent contaminants (Mackay et al., 2014), making themaccessible to humans through environmental exposure.

The effects of pharmaceuticals on social development can beconveniently modeled in zebrafish. For example, prenatal exposureto valproic acid can lead to fetal valproate syndrome (Box 2) inhumans. Embryonic exposure to valproic acid or sodium valproateinduced deficits in social preference behavior (Bailey et al., 2016;Baronio et al., 2018; Dwivedi et al., 2019; Zimmermann et al.,2015) but not aggression (Zimmermann et al., 2015). Impairmentsin the histaminergic (Baronio et al., 2018) and purinergic(Zimmermann et al., 2017) systems likely mediate this effect.

Embryonic exposure to 2 nM retinoic acid, an importantsignaling mediator in development, decreased social preference toa video of shoaling fish without inducing neural tube malformationsor elevated death rate (Bailey et al., 2016).

Fluoroquinolones and tetracyclines are β-diketone antibiotics(DKAs) widely used in humans and animals. A 3-month exposureto a mixture of six DKA species, starting from birth, increasedshoaling at a low concentration (6.25 mg/l) but inhibited shoalcohesion at a higher concentration (25 mg/l) (Wang et al., 2016b).

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Environmental chemicalsExpansion of the chemical industry in the past century has greatlyincreased the number of environmental chemicals, yet only afraction of these have been studied for their effects on thedevelopment of social behavior. Some commonly foundenvironmental toxins have been studied in the zebrafish socialbehavior model. Benzo[α]pyrene often forms during organic-mattercombustion and is found in cigarette smoke, diesel exhaust andgrilled foods. When tested across three generations, benzo[α]pyreneinduced a shoaling deficit in the first but not the subsequentgenerations (Knecht et al., 2017).Chemical flame retardants are added to many household products.

Among these, the brominated flame retardant (BFR) polybrominateddiphenyl ethers (PBDEs) were widely used until the early 2000s.Althoughnow largely phased out due to toxicity concerns, they persistin the environment, which can lead to continuous low-level exposure.When exposed to low doses of either of two prominent PBDEs, BDE-99 and BDE-47, zebrafish exposed to BDE-99 but not BDE-47exhibited reduced social preference behavior (Glazer et al., 2018b).Another study reported elevated shoaling between pairs of zebrafishlarvae following embryonic BDE-47 treatment (Zhang et al., 2017).Interestingly, the same group also tested two BDE-47 metabolites, 6-OH-BDE-47 and 6-MeO-BDE-47, using the same experimentalsetup, and found that 6-MeO-BDE-47 but not 6-OH-BDE-47inhibited shoaling (Zhang et al., 2018). Another BFR,tetrabromobisphenol A, heightened aggression in males but not infemales (Chen et al., 2016a).BFRs have been largely replaced by a newer class of flame

retardants, the organophosphate flame retardants (OPFRs).Currently, little is known about the potential developmentalneurotoxicity of these chemicals. Six commonly used OPFRsshowed no negative effect on shoaling behavior through embryonicexposure (Glazer et al., 2018a; Oliveri et al., 2015). A mixture ofBFRs and OPFRs, FM 550 did, however, induce shoaling deficits(Bailey and Levin, 2015).The organophosphorus pesticide dichlorvos (Altenhofen et al.,

2019) and the neonicotinoid pesticide imidacloprid (Crosby et al.,2015) showed no effect on social behavior.Endocrine-disrupting chemicals (EDCs) such as xenoestrogen

have been suspected of affecting social behavior. Indeed, embryonicexposure to 17α-ethinylestradiol enhanced social preferencebehavior (Volkova et al., 2015).BPA increased time spent near a mirror, but reduced male attacks

on the mirror (Weber et al., 2015).The heavy metals lead and arsenic were also tested, with

lead exposure increasing aggression in a mirror test (Weber andGhorai, 2013) and arsenic showing no effect on social behavior(Dipp et al., 2018).

Maternal exposureBecause humans develop in utero, environmental risk factors forsocial-behavior-related disorders must access the fetus throughmaternal exposure. Although exposure mechanisms in egg-layingfish and placental animals are significantly different, it is possible tomodel some aspects of this exposure mechanism in zebrafish. Forexample, exposing adult female zebrafish to a mixture of the water-soluble fraction of crude oil and lead was found to suppress shoalingbehavior in their offspring (Wang et al., 2016c).

Chemically induced models: adult exposureAdult zebrafish can be used for pharmacological and toxicologicalstudies. Drugs can be easily administered by direct water

immersion, which enables drug absorption through the skin andgill, or oral ingestion. Both acute and chronic drug exposure can beconducted with good temporal control, as drugs can be added andremoved at precise time points. To overcome potential issues in drugsolubility and to enable pharmacokinetic analyses, drugs can also beapplied by oral administration (Kulkarni et al., 2014; Dang et al.,2016) or intraperitoneal injection (Samaee et al., 2017). Drugabsorption and metabolism can be measured by mass spectrometry(Villacrez et al., 2018).

Dietary componentsChronic exposure to dietary components can affect a body’snutritional and toxicological balance, which in turn modulate theoverall health of an animal through regulation of metabolism andgene expression. Trace elements such as selenium and zinc areessential nutrients for mammals but are neurotoxic at excessivelevels and their neurobehavioral effects on social behavior are notwell understood. Chronic (60 days) exposure to selenomethionine, anaturally occurring selenoamino acid found in cereal grains,grassland legumes and soybeans (Whanger, 2002), suppressedshoaling in adult fish, potentially due to alterations of theserotonergic pathway (Attaran et al., 2019). Chronic (21 days)exposure to zinc chloride reduced mirror-biting behavior(Sarasamma et al., 2018). Hyperprolinemia is an inheriteddisorder of proline metabolism deficiency and has been associatedwith schizoaffective disorders (Jacquet et al., 2005; Oreši�c et al.,2011). To examine the effect of excess proline on social behavior,adult fish were exposed to 1.5 mM proline for 7 days. Impairmentsin social preference and other schizophrenia-related behaviors werefound and rescued by the atypical antipsychotic drug sulpiride butnot the typical antipsychotic haloperidol (Savio et al., 2012).

Environmental chemicalsDirect short-term (days) exposure to the herbicides glyphosate(Bridi et al., 2017) and atrazine (Schmidel et al., 2014) reducedaggressive behavior and shoaling, respectively, whereas an 18-dayexposure to intraperitoneally injected paraquat did not significantlyaffect social interaction (Bortolotto et al., 2014). Acute exposure togold resulted in a temporary reduction in social preference behaviorthat may be related to elevated oxidative stress; the social inhibitioneffect was short lived and the treated fish recovered within severalhours (Strungaru et al., 2018). Chronic exposure to the EDC BPAreduced courtship behavior in females but increased theiraggression towards mating competitors; females also preferredcontrol males over BPA-treated males during courtship tests (Liet al., 2017a). Nonylphenol, another EDC and xenoestrogencompound, inhibited aggression and social preference behaviorsby chronic exposure (Xia et al., 2010). 17α-ethinylestradiol, asynthetic estrogen and major component in oral contraceptive pills,is excreted from the human body in high amounts and accumulatesin the environment. Its impact on zebrafish social behavior wereexamined in several studies to assess its influence on aquaticanimals, revealing changes in social hierarchy and courtship in fishfollowing exposure (Coe et al., 2008, 2009; Colman et al., 2009;Filby et al., 2012). Another EDC, triclosan, had inconsistent effectson social preference behavior (Liu et al., 2018b; Zang et al., 2019).

Neuroactive chemicalsNeuroactive chemicals have been applied to adult fish directly toinvestigate how different neurotransmitter pathways contribute tothe regulation of social behavior and to examine a drug’s therapeuticpotential in treating social disorders. Oxytocin (OT) and arginine-

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vasopressin (AVP) are neuropeptides known to regulate socialbehavior in mammals. Their zebrafish homologs, isotocin (IT) andvasotocin (AVT), together with the mammalian OT and AVP, wereexamined in a social preference assay in which a WT test subjectwas placed betweenWT and nacre fish. Control- and vehicle-treatedfish prefer to stay close to the WT social stimulus, whereasincreasing doses of all four neuropeptides first reversed thispreference, and then returned it to baseline, meaning that, atmedium doses, the treated fish preferred to stay closer to the nacrethan to the WT social stimulus (Braida et al., 2012). A syntheticoxytocin receptor ligand, dOTK2–C8, elicited a similar preference-reversal phenotype (Busnelli et al., 2016).The dopaminergic system has been implicated in reward and

social responses. Not surprisingly, the dopamine D1 receptorantagonist SCH23390 significantly reduced social preference in theWTAB zebrafish strain. Interestingly, researchers failed to observea similar effect in another WT zebrafish strain, demonstratingnatural variation in behavioral responses to neuroactive chemicals indifferent zebrafish strains (Scerbina et al., 2012). The commonprescription drugs fluoxetine (Giacomini et al., 2016) andbenzodiazepines (Giacomini et al., 2016; Schaefer et al., 2015)both inhibited shoaling. Fluoxetine also inhibited the offensiveaggression behavior in dominant fish while suppressing freezingbehavior in the subordinate fish (Theodoridi et al., 2017).The glutamatergic N-methyl-d-aspartate receptor antagonist MK-

801, commonly used to inhibit memory formation, has been used tocreate fish models with autism- and schizophrenia-like behavioraldeficits. Acute exposure to MK-801 decreases social preference(Dreosti et al., 2015), shoaling (Maaswinkel et al., 2013a) andaggression (Zimmermann et al., 2016), an effect rescued byoxytocin and the oxytocin receptor agonist carbetocin(Zimmermann et al., 2016). Atypical antipsychotics sulpiride andolanzapine also reversed MK-801-induced social impairment, yetthe typical antipsychotic haloperidol failed to reverse thisphenotype (Seibt et al., 2011).Nicotine significantly inhibits shoal cohesion but only mildly

affects polarization, whereas ethanol strongly affects polarizationwithin a fish school but only modestly inhibits shoal cohesion (Milleret al., 2013). In a social novelty test (Ariyasiri et al., 2019), control fishtypically prefer to interact with a novel over a familiar fish. Ethanolexposure significantly suppressed this novelty preference behaviorwithout affecting sociality in a three-chamber social preference test(Ariyasiri et al., 2019). Individual fish also respond differently toethanol. While ‘shy’ individuals typically spent more time near ashoal than ‘bold’ fish, ethanol increased shoaling in bold fish butinhibited shoaling in shy fish (Araujo-Silva et al., 2018). The acutemild inhibitory effect of ethanol on sociality is enhanced by taurine, acommon supplement in energy drinks (Fontana et al., 2018). Taurinealso prevented alcohol-induced elevated aggression (Fontana et al.,2016).While acute ethanol exposuremildly inhibits shoaling, chronic(8 days) exposure to ethanol surprisingly increases shoal cohesion(Müller et al., 2017b). Chronic ethanol exposure dramatically loweredfertility when at least one of the mating partners was treated, and thisinhibition was fully reversed by a 9-week withdrawal program(Dewari et al., 2016).The psychotropic drug lysergic acid diethylamide (LSD)

inhibited shoaling (Green et al., 2012; Grossman et al., 2010) butnot social preference behavior (Grossman et al., 2010). Similarto the effects of oxytocin and arginine-vasopressin receptoragonists, the amphetamine derivatives 2,5-dimethoxy-4-bromo-amphetamine hydrobromide, para-methoxyamphetamine and 3,4-methylenedioxymethamphetamine generated an inverted-U-shaped

curve in the nacre/WT social preference assay, shifting socialpreference fromWT conspecifics to nacre and then back to WT fishat progressively increasing doses. Ketamine (Riehl et al., 2011) andibogaine (Cachat et al., 2013) both inhibited group cohesion.

Stressor-induced modelsExternal stressorsUnpredictable chronic stress (UCS) and developmental socialisolation (DSI) are often applied to animal models to mimic theenvironmental stressors that may contribute to psychiatric disorderdevelopment in humans. Zebrafish UCS assays apply differentcombinations of chronic stressors – such as restraint, social isolation,overcrowding, tank or water change, cold/heat, being chased by a net,dorsal body exposure in shallow water, exposure to air in a net,predator presence, and alarm substance – for varying durations (daysto weeks). Stressors are often randomized on different days to ensureunpredictability. UCS assays with different stress protocols havegenerated inconsistent results, including increased (Chakravarty et al.,2013), first increased and then decreased (Piato et al., 2011), orunaltered (Fulcher et al., 2017) shoaling behavior after UCS. Acutestress by harassing the fish with a pen net prior to a behavioral testdecreased social preference behavior but increased aggression(Giacomini et al., 2016). The effect of DSI on shoaling alsoremains controversial, as different reports have found it decreased(Shams et al., 2018) or did not alter (Fulcher et al., 2017) shoaling.

Physiological stressorsAn induced inflammatory response by inoculating fishwith formalin-inactivatedAeromonashydrophila reduced social preferencebehavior(Kirsten et al., 2018), consistent with a previous report linking theimmune system with social behavior in mice (Filiano et al., 2016).Traumatic brain injury (TBI) by pulsed, high-intensity focusedultrasound to the adult zebrafish brain increased shoaling cohesion(McCutcheon et al., 2017), although it may be difficult to determinethe exact location and degree of brain damage caused by such adiffusive injury method. Hunger reduced aggression in females butnot in males, possibly due to the females’ stronger need to conserveenergy compared to males (Ariyomo and Watt, 2015).

Circuit manipulation modelsDifferent parts of the subcortical social brain (SSB) play differentroles in social behavior. Manipulating these brain regions and neuralcircuits through targeted neuronal inhibition, ablation and activationusing genetic, optogenetic and chemogenetic (Box 2) approachescan help improve our understanding of the mechanisms regulatingdifferent aspects of social behavior. For example, targetedexpression of tetanus neurotoxin to silence the lateral or medialsubregion of the dorsal habenula (Table 1; Fig. 2) resulted inpredispositions to lose or win a fight, respectively, revealing a dualcontrol system for conflict resolution (Chou et al., 2016). In anotherstudy, manual (by inserting a 27½ G needle) and genetic ablationsof a population of neurons in the ventral telencephalon inhibitedsocial interactions, as quantified by failure to adjust orientationagainst a social stimulus fish (Stednitz et al., 2018). The ablatedregion is believed to be homologous to the mammalian lateralseptum (Table 1; Fig. 2), a region implicated in social behavior inmammals (Clarke and File, 1982; Shin et al., 2018).

Emerging technologies for modeling social behaviordisorders in zebrafish: opportunities and challengesIn this section, we discuss emerging technologies that canpotentially improve modeling of social behavior disorders in

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zebrafish. These can be broadly categorized as the ‘next generation’methods for high-throughput model generation and drug testing,high-resolution functional brain imaging, and high-precision circuitmanipulation for studying the circuit-level mechanisms ofbehavioral deficits. These research goals, limitations of currentmethodologies and potential solutions to overcome these limitationsare summarized in Table 2.

High-throughput genome editing for disease modelingMany neuropsychiatric disorders with social deficits have a stronggenetic basis. Advanced genetic and genomic technologies haveenabled researchers to find hundreds of genes that contribute to risksof developing neurological diseases. Given that the zebrafish isrelatively inexpensive and easy to manipulate genetically comparedto rodents, it has great potential as an experimental model to studythese disease risk genes.CRISPR is a popular technology for genome editing in zebrafish

due to its simplicity and speed (Hwang et al., 2013; Prykhozhijet al., 2017; Prykhozhij and Berman, 2018). Researchers haveattempted to improve throughput by developing more scalablemethods. Current approaches are based on pooled CRISPRtargeting followed by individual genotyping and separation, buthave yet to provide a truly high-throughput output (Varshney et al.,2015; Shah et al., 2015). Several possible approaches may improvethe current methods. Pooled CRISPR followed by early genotypingof live larvae using a recently developed approach (Lambert et al.,2018) can significantly speed up the turnover for each round ofgenotyping. Robotically controlled and fully automated embryonicinjection methods (Zhao et al., 2018) also have the potential to

increase the throughput of CRISPR delivery. Automated feedingsystems such as Tritone (Aquatic Solutions) may facilitate thehusbandry of large numbers of mutant lines generated by high-throughput CRISPR editing. Finally, if large numbers of disease-related mutants are generated, expanding the capacity of zebrafishstock centers may be needed (Table 2).

High-throughput chemical screening for disease modeling and drugdiscoveryBoth genes and the environment contribute to the development ofsocial behavior. The development of some social-related disordersis also believed to be affected by environmental factors such asprenatal exposure to certain chemicals. The zebrafish has been apopular model for in vivo chemical screening (Rennekamp andPeterson, 2015). Its ex utero development allows embryos to beexposed to potentially toxic chemicals during early embryogenesis.The zebrafish larva is small, and a large number of larvae can fit intoa compact imaging arena, enabling high-throughput behavioralprofiling and phenotype-based drug discovery (Jordi et al., 2018;Bruni et al., 2016; Kokel et al., 2010, 2012; Rihel et al., 2010).These features make zebrafish an attractive model for systematicallyidentifying potential environmental risk factors that contribute todisease etiology by high-throughput chemical and behavioralscreening. Although technologies are readily available to exposezebrafish embryos, larvae or adults to chemicals in a high-throughput or scalable manner, a social behavior testing systemcapable of operating in a high-throughput or scalable fashion has yetto be developed (Table 2). The establishment of such a high-throughput social behavior assay in zebrafish would enable

Table 1. Anatomical and functional conservation of the subcortical social brain between mammals and zebrafish

Mammalian structures Mammalian functions Homologous zebrafish structures

Anterior hypothalamus (AH) Aggression (Falkner and Lin, 2014) Ventral tuberal nucleus (VTN) (Xie and Dorsky, 2017)Basolateral amygdala (BLA) Social fear (Qi et al., 2018) Medial dorsal telencephalon (Dm) (von Trotha et al.,

2014, Perathoner et al., 2016)Cerebellum (CB) Social reward (Carta et al., 2019) CB (Bae et al., 2009)Dorsal raphe (DR) Social isolation (Matthews et al., 2016) DR (Yokogawa et al., 2012)Hippocampus (HIP) Social memory (Hitti and Siegelbaum, 2014; Okuyama

et al., 2016; Meira et al., 2018)Lateral dorsal telencephalon (Dl) (von Trotha et al., 2014)

Lateral habenula (LHb) Aggression (Flanigan et al., 2017), social play (van Kerkhofet al., 2013), social defeat (Wang et al., 2017a)

Ventral habenula (VHb) (Amo et al., 2010)

Lateral septum (LS) Aggression (Leroy et al., 2018), early-life stress-inducedsocial dysfunction (Shin et al., 2018)

Ventral nucleus of the ventral telencephalon (Vv)

Medial amygdala (MeA) Sexual behavior (Ferrero et al., 2013), sex discrimination ofsocial cues (Yao et al., 2017), social informationprocessing (Li et al., 2017b), social recognition(Takayanagi et al., 2017), aggression and parenting(Tachikawa et al., 2013)

Supracommissural nucleus of the ventral telencephalon(Vs) (Perathoner et al., 2016)

Medial bed nucleus of the striaterminalis (BNSTm)

Stress response (Lebow and Chen, 2016), sexual behaviorand parenting (Tsuneoka et al., 2015)

Supracommissural nucleus of the ventraltelencephalon (Vs)

Medial preoptic area (MPOA) Sexually dimorphic behaviors (Wei et al., 2018), socialreward (McHenry et al., 2017), parenting (Fang et al.,2018; Wu et al., 2014; Brown et al., 2017)

Preoptic area (POA) (Xie and Dorsky, 2017)

Nucleus accumbens (NAc) Social reward (Dölen et al., 2013) Dorsal ventral telencephalon (Vd)Periaqueductal gray/central gray(PAG/CG)

Defensive behavior (Deng et al., 2016) PAG/CG

Striatum (STR) Pair bonding (Báez-Mendoza and Schultz, 2013) Dorsal (Vd) and central (Vc) ventral telencephalonVentral tegmental area (VTA) Social reward (Hung et al., 2017) Posterior tuberculum (PT)Ventral pallidum (VP) Sexual behavior, social affiliation (Smith et al., 2009) N.A.Ventromedial hypothalamus (VMH) Aggression (Hashikawa et al., 2017), defensive behavior

(Wang et al., 2019), sexual behavior (Nomoto andLima, 2015)

Anterior tuberal nucleus (ATN) (Xie and Dorsky, 2017)

Recent experimental evidence of SSB conservation between zebrafish andmammals are referenced in column 3. Additional references covering earlier researchcan be found in the review by O’Connell and Hofmann (2011b). Structures are listed in alphabetical order.

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researchers to systematically screen chemicals for their disease-inducing risks and discover new drugs for treating social behaviordeficits in humans.

Neural activity imaging and circuit manipulation technologies forsocial disorder modelsThe circuit-level mechanisms underlying social behavior anddisorders are not well understood. The zebrafish is a promisingmodel for elucidating these mechanisms because, compared torodents, it is relatively easy to image due to its small size andtransparent nature. Furthermore, it is amenable to facile circuitmanipulations through genetically targeted ablation, or optical andchemical activation or inhibition. Although many of thesetechnologies are already established in zebrafish, they have rarelybeen used to investigate social behavior.Here,we discuss the potentialto use imaging and circuit manipulation techniques to study brainactivities in social behavior and disease models (Table 2).Real-time calcium imaging has long been applied to larval

zebrafish less than a week old. Researchers recently developed atwo-photon calcium imaging approach that enables real-time brainimaging of 3-week-old zebrafish (Jetti et al., 2014; Vendrell-Llopisand Yaksi, 2015), a stage when robust social preference behavior isdeveloped. Although, in the current methods, the fish must berestrained for imaging, combining this method with VR technologymay allow brain activity imaging during a virtual social interaction.In addition, with the recent advancements in real-time brain imagingof freely moving larvae (Kim et al., 2017a; Cong et al., 2017; Mutoand Kawakami, 2016), it may one day be possible to developcalcium imaging methods for freely moving 3-week-old fish duringphysical social interactions. Alternatively, whole-brain or whole-body tissue clearing methods such as CLARITY and PACT havebeen successfully applied to adult zebrafish (Cronan et al., 2015),and could enable post-hoc analysis of whole-brain activity patternsduring social interactions by examining the expression of immediateearly genes (Box 2).Conventional methods in zebrafish manipulate circuit activity by

inhibiting neuronal activity through expression of neurotoxins suchas tetanus or botulinum toxins, or ablation of targeted neurons byexpressing nitroreductase (Curado et al., 2008). Newer technologiessuch as optogenetics (Förster et al., 2017) and chemogenetics (Chenet al., 2016b) (Box 2) can be applied to zebrafish to activate orinhibit certain brain regions. It is also possible to combine bothmethods by applying an optically switchable compound to activatecertain neurons (Lam et al., 2017). These newer methods canactivate specific neurons with reversible temporal control.

ConclusionsAnimal models for behavioral disorders are inevitably confrontedwith questions about their validity. This is true for emerging modelorganisms such as the zebrafish as well as for established ones suchas rodents. Care must be taken when interpreting results acquiredfrom animal models that attempt to mimic symptoms of humanconditions. This is especially true for complex traits such as socialbehaviors. Nevertheless, behavioral assays often provide readoutsthat are more relevant to the core symptoms of human behaviordisorders than other assays that examine changes in anatomy,physiology or endophenotypes. Therefore, efforts in advancing thecurrent assay and analysis methods of social behavior are necessaryto facilitate progress in disease research.

The extensive data discussed in this Review support the idea thatmany of the most fundamental elements of social behavior – e.g.conspecific association, communication, establishment of hierarchies,social eavesdropping, aggression andmating – are conserved in socialvertebrates from teleosts to mammals. Vertebrates as evolutionarilydistant as zebrafish and rodents share numerous genetic,pharmacological, neuroanatomical and behavioral similaritiesrelevant to social behavior. Common structures in the SSB mayprovide a biological foundation for social behavior conservationamong vertebrates. We argue that the more complex, higher-ordersocial behaviors in humans must be understood as layered on top ofthe SSB, and studying the zebrafish SSB can therefore have directimplications for understanding sociality in humans. Given thenumerous methods currently available for studying various aspectsof social behavior in zebrafish, the existing zebrafish models of socialdeficits and the technologies (established and emergent) for high-throughput experimentation, we anticipate that the zebrafish SSBwillbecome an increasingly important model for understanding thebiology of sociality in health and disease.

Competing interestsThe authors declare no competing or financial interests.

FundingThis research received no specific grant from any funding agency in the public,commercial or not-for-profit sectors.

ReferencesAbril-de-Abreu, R., Cruz, A. S. and Oliveira, R. F. (2015a). Social dominance

modulates eavesdropping in zebrafish.R. Soc. Open Sci. 2, 150220. doi:10.1098/rsos.150220

Abril-de-Abreu, R., Cruz, J. and Oliveira, R. F. (2015b). Social eavesdropping inzebrafish: tuning of attention to social interactions. Sci. Rep. 5, 12678. doi:10.1038/srep12678

Table 2. Potential applications of emerging technologies to improve social disorder modeling in zebrafish.

Research goals Limitations of current methods Possible solutions

High-throughput genome editing fordisease modeling

• Mutagenesis methods are low throughput• Labor-intensive husbandry• Limited resources for husbandry of mutant lines

• Rapid genotyping for fast turnaround• Automated microinjection• Automated fish husbandry• Expansion of fish husbandry capacity

High-throughput behavioralscreening for disease modeling ordrug discovery

• Current social behavior assays are low throughput • High-throughput or scalable social behavior assays

Investigating circuit-levelmechanisms underlying deficits ofsocial disease models

• Lack of real-time imaging capability for older or freelymoving fish

• Lack of whole-brain activity imaging methods• Lack of circuit activation methods• Low temporal resolution in circuit manipulation

approaches

• Adopt recent advances in real-time brain imaging, whole-body hydrogel tissue chemistry methods, andoptogenetic- and chemogenetic-based circuitmanipulation approaches

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Disea

seModels&Mechan

isms

Adolphs, R. (2003). Cognitive neuroscience of human social behaviour. Nat. Rev.Neurosci. 4, 165-178. doi:10.1038/nrn1056

Adolphs, R. (2009). The social brain: neural basis of social knowledge. Annu. Rev.Psychol. 60, 693-716. doi:10.1146/annurev.psych.60.110707.163514

Al-Jubouri, Q., Al-Nuaimy, W., Al-Taee, M. A. and Young, I. (2017). ComputerStereovision System for 3D Tracking of Free-Swimming Zebrafish. 2017 10thInternational Conference on Developments in eSystems Engineering (DeSE).doi:10.1109/DeSE.2017.31

Altenhofen, S., Nabinger, D. D., Bitencourt, P. E. R. and Bonan, C. D. (2019).Dichlorvos alters morphology and behavior in zebrafish (Danio rerio) larvae.Environ. Pollut. 245, 1117-1123. doi:10.1016/j.envpol.2018.11.095

Amo, R., Aizawa, H., Takahoko, M., Kobayashi, M., Takahashi, R., Aoki, T. andOkamoto, H. (2010). Identification of the zebrafish ventral habenula as a homologof the mammalian lateral habenula. J. Neurosci. 30, 1566-1574. doi:10.1523/JNEUROSCI.3690-09.2010

Araujo-Silva, H., Pinheiro-da-Silva, J., Silva, P. F. and Luchiari, A. C. (2018).Individual differences in response to alcohol exposure in zebrafish (Danio rerio).PLoS ONE 13, e0198856. doi:10.1371/journal.pone.0198856

Arganda, S., Perez-Escudero, A. and de Polavieja, G. G. (2012). A common rulefor decision making in animal collectives across species. Proc. Natl. Acad. Sci.USA 109, 20508-20513. doi:10.1073/pnas.1210664109

Ariyasiri, K., Choi, T.-I., Kim, O.-H., Hong, T. I., Gerlai, R. and Kim, C.-H. (2019).Pharmacological (ethanol) and mutation (sam2 KO) induced impairment ofnovelty preference in zebrafish quantified using a new three-chamber socialchoice task. Prog. Neuropsychopharmacol. Biol. Psychiatry 88, 53-65. doi:10.1016/j.pnpbp.2018.06.009

Ariyomo, T. O. and Watt, P. J. (2015). Effect of hunger level and time of day onboldness and aggression in the zebrafish Danio rerio. J. Fish Biol. 86, 1852-1859.doi:10.1111/jfb.12674

Armbruster, B. N., Li, X., Pausch, M. H., Herlitze, S. and Roth, B. L. (2007).Evolving the lock to fit the key to create a family of G protein-coupled receptorspotently activated by an inert ligand. Proc. Natl. Acad. Sci. USA 104, 5163-5168.doi:10.1073/pnas.0700293104

Ashwood, P., Kwong, C., Hansen, R., Hertz-Picciotto, I., Croen, L., Krakowiak,P., Walker, W., Pessah, I. N. and van de Water, J. (2008). Brief report: plasmaleptin levels are elevated in autism: association with early onset phenotype?J. Autism Dev. Disord. 38, 169-175. doi:10.1007/s10803-006-0353-1

Atmaca, M., Kuloglu, M., Tezcan, E. and Ustundag, B. (2003). Serum leptin andcholesterol levels in schizophrenic patients with and without suicide attempts.Acta Psychiatr. Scand. 108, 208-214. doi:10.1034/j.1600-0447.2003.00145.x

Attaran, A., Salahinejad, A., Crane, A. L., Niyogi, S. and Chivers, D. P. (2019).Chronic exposure to dietary selenomethionine dysregulates the genes involved inserotonergic neurotransmission and alters social and antipredator behaviours inzebrafish (Danio rerio). Environ. Pollut. 246, 837-844. doi:10.1016/j.envpol.2018.12.090

Audira, G., Sarasamma, S., Chen, J.-R., Juniardi, S., Sampurna, B. P., Liang, S.-T., Lai, Y.-H., Lin, G.-M., Hsieh, M.-C. and Hsiao, C.-D. (2018a). Zebrafishmutants carrying leptin a (lepa) gene deficiency display obesity, anxiety, lessaggression and fear, and circadian rhythm and color preference dysregulation.Int. J. Mol. Sci. 19, E4038. doi:10.3390/ijms19124038

Audira, G., Sampurna, B. P., Juniardi, S., Liang, S.-T., Lai, Y.-H. andHsiao, C.-D.(2018b). A simple setup to perform 3D locomotion tracking in zebrafish by using asingle camera. Inventions 3, 11. doi:10.3390/inventions3010011

Autism Genome Project Consortium, Szatmari, P., Paterson, A. D.,Zwaigenbaum, L., Roberts, W., Brian, J., Liu, X. Q., Vincent, J. B., Skaug,J. L., Thompson, A. P., Senman, L., et al. (2007). Mapping autism risk loci usinggenetic linkage and chromosomal rearrangements. Nat. Genet. 39, 319-328.doi:10.1038/ng1985

Bae, Y.-K., Kani, S., Shimizu, T., Tanabe, K., Nojima, H., Kimura, Y.,Higashijima, S.-I. and Hibi, M. (2009). Anatomy of zebrafish cerebellum andscreen for mutations affecting its development. Dev. Biol. 330, 406-426. doi:10.1016/j.ydbio.2009.04.013

Baez-Mendoza, R. and Schultz, W. (2013). The role of the striatum in socialbehavior. Front. Neurosci. 7, 233. doi:10.3389/fnins.2013.00233

Bai, Y.-X., Zhang, S.-H., Fan, Z., Liu, X.-Y., Zhao, X., Feng, X.-Z. and Sun, M.-Z.(2018). Automatic multiple zebrafish tracking based on improved HOG features.Sci. Rep. 8, 10884. doi:10.1038/s41598-018-29185-0

Bailey, J. M. and Levin, E. D. (2015). Neurotoxicity of FireMaster 550® in zebrafish(Danio rerio): chronic developmental and acute adolescent exposures.Neurotoxicol. Teratol. 52, 210-219. doi:10.1016/j.ntt.2015.07.001

Bailey, J. M., Oliveri, A. N., Karbhari, N., Brooks, R. A., De La Rocha, A. J.,Janardhan, S. and Levin, E. D. (2016). Persistent behavioral effects followingearly life exposure to retinoic acid or valproic acid in zebrafish. Neurotoxicology52, 23-33. doi:10.1016/j.neuro.2015.10.001

Baronio, D., Puttonen, H. A. J., Sundvik, M., Semenova, S., Lehtonen, E. andPanula, P. (2018). Embryonic exposure to valproic acid affects the histaminergicsystem and the social behaviour of adult zebrafish (Danio rerio). Br. J. Pharmacol.175, 797-809. doi:10.1111/bph.14124

Bartolini, T., Mwaffo, V., Showler, A., Macrì, S., Butail, S. and Porfiri, M. (2016).Zebrafish response to 3D printed shoals of conspecifics: the effect of body size.Bioinspir. Biomim. 11, 026003. doi:10.1088/1748-3190/11/2/026003

Berman, G. J., Choi, D. M., Bialek, W. and Shaevitz, J. W. (2014). Mapping thestereotyped behaviour of freely moving fruit flies. J. R Soc. Interface 11,20140672. doi:10.1098/rsif.2014.0672

Bernier, R., Golzio, C., Xiong, B., Stessman, H. A., Coe, B. P., Penn, O.,Witherspoon, K., Gerdts, J., Baker, C., Vulto-van Silfhout, A. T., et al. (2014).Disruptive CHD8 mutations define a subtype of autism early in development. Cell158, 263-276. doi:10.1016/j.cell.2014.06.017

Biechl, D., Tietje, K., Gerlach, G. and Wullimann, M. F. (2016). Crypt cells areinvolved in kin recognition in larval zebrafish. Sci. Rep. 6, 24590. doi:10.1038/srep24590

Bishop, B. H., Spence-Chorman, N. and Gahtan, E. (2016). Three-dimensionalmotion tracking reveals a diving component to visual and auditory escape swimsin zebrafish larvae. J. Exp. Biol. 219, 3981-3987. doi:10.1242/jeb.147124

Blakemore, S.-J. (2008). The social brain in adolescence. Nat. Rev. Neurosci. 9,267-277. doi:10.1038/nrn2353

Blakemore, S.-J. (2012). Development of the social brain in adolescence. J. R Soc.Med. 105, 111-116. doi:10.1258/jrsm.2011.110221

Blaker-Lee, A., Gupta, S., Mccammon, J. M., de Rienzo, G. and Sive, H. (2012).Zebrafish homologs of genes within 16p11.2, a genomic region associated withbrain disorders, are active during brain development, and include two deletiondosage sensor genes. Dis. Model. Mech. 5, 834-851. doi:10.1242/dmm.009944

Blardi, P., de Lalla, A., D’ambrogio, T., Zappella, M., Cevenini, G., Ceccatelli, L.,Auteri, A. and Hayek, J. (2007). Rett syndrome and plasma leptin levels.J. Pediatr. 150, 37-39. doi:10.1016/j.jpeds.2006.10.061

Blardi, P., de Lalla, A., D’ambrogio, T., Vonella, G., Ceccatelli, L., Auteri, A. andHayek, J. (2009). Long-term plasma levels of leptin and adiponectin in Rettsyndrome. Clin. Endocrinol. 70, 706-709. doi:10.1111/j.1365-2265.2008.03386.x

Blardi, P., de Lalla, A., Ceccatelli, L., Vanessa, G., Auteri, A. and Hayek, J.(2010). Variations of plasma leptin and adiponectin levels in autistic patients.Neurosci. Lett. 479, 54-57. doi:10.1016/j.neulet.2010.05.027

Bortolotto, J.W., Cognato,G. P., Christoff, R. R., Roesler, L. N., Leite, C. E., Kist,L. W., Bogo, M. R., Vianna, M. R. and Bonan, C. D. (2014). Long-term exposureto paraquat alters behavioral parameters and dopamine levels in adult zebrafish(Danio rerio). Zebrafish 11, 142-153. doi:10.1089/zeb.2013.0923

Braida, D., Donzelli, A., Martucci, R., Capurro, V., Busnelli, M., Chini, B. andSala, M. (2012). Neurohypophyseal hormones manipulation modulate social andanxiety-related behavior in zebrafish. Psychopharmacology (Berl.) 220, 319-330.doi:10.1007/s00213-011-2482-2

Bridi, D., Altenhofen, S., Gonzalez, J. B., Reolon, G. K. and Bonan, C. D. (2017).Glyphosate and Roundup® alter morphology and behavior in zebrafish.Toxicology 392, 32-39. doi:10.1016/j.tox.2017.10.007

Brown, A. E. X., Yemini, E. I., Grundy, L. J., Jucikas, T. and Schafer, W. R.(2013). A dictionary of behavioral motifs reveals clusters of genes affectingCaenorhabditis elegans locomotion. Proc. Natl. Acad. Sci. USA 110, 791-796.doi:10.1073/pnas.1211447110

Brown, R. S. E., Aoki, M., Ladyman, S. R., Phillipps, H. R., Wyatt, A., Boehm, U.and Grattan, D. R. (2017). Prolactin action in the medial preoptic area isnecessary for postpartum maternal nursing behavior. Proc. Natl. Acad. Sci. USA114, 10779-10784. doi:10.1073/pnas.1708025114

Bruni, G., Rennekamp, A. J., Velenich, A., Mccarroll, M., Gendelev, L., Fertsch,E., Taylor, J., Lakhani, P., Lensen, D., Evron, T. et al. (2016). Zebrafishbehavioral profiling identifies multitarget antipsychotic-like compounds. Nat.Chem. Biol. 12, 559-566. doi:10.1038/nchembio.2097

Buske, C. and Gerlai, R. (2011). Early embryonic ethanol exposure impairsshoaling and the dopaminergic and serotoninergic systems in adult zebrafish.Neurotoxicol. Teratol. 33, 698-707. doi:10.1016/j.ntt.2011.05.009

Busnelli, M., Kleinau, G., Muttenthaler, M., Stoev, S., Manning, M., Bibic, L.,Howell, L. A., Mccormick, P. J., di Lascio, S., Braida, D. et al. (2016). Designand characterization of superpotent bivalent ligands targeting oxytocin receptordimers via a channel-like structure. J. Med. Chem. 59, 7152-7166. doi:10.1021/acs.jmedchem.6b00564

Butail, S. andPaley, D. A. (2012). Three-dimensional reconstruction of the fast-startswimming kinematics of densely schooling fish. J. R Soc. Interface 9, 77-88.doi:10.1098/rsif.2011.0113

Butail, S., Bartolini, T. and Porfiri, M. (2013a). Collective response of zebrafishshoals to a free-swimming robotic fish.PLoSONE 8, e76123. doi:10.1371/journal.pone.0076123

Butail, S., Bollt, E. M. and Porfiri, M. (2013b). Analysis and classification ofcollective behavior using generative modeling and nonlinear manifold learning.J. Theor. Biol. 336, 185-199. doi:10.1016/j.jtbi.2013.07.029

Butail, S., Mwaffo, V. and Porfiri, M. (2016). Model-free information-theoreticapproach to infer leadership in pairs of zebrafish.Phys. Rev. E 93, 042411. doi:10.1103/PhysRevE.93.042411

Cachat, J., Kyzar, E. J., Collins, C., Gaikwad, S., Green, J., Roth, A., El-Ounsi,M., Davis, A., Pham,M., Landsman, S. et al. (2013). Unique and potent effects ofacute ibogaine on zebrafish: the developing utility of novel aquatic models for

14

REVIEW Disease Models & Mechanisms (2019) 12, dmm039446. doi:10.1242/dmm.039446

Disea

seModels&Mechan

isms

hallucinogenic drug research. Behav. Brain Res. 236, 258-269. doi:10.1016/j.bbr.2012.08.041

Carta, I., Chen, C. H., Schott, A. L., Dorizan, S. and Khodakhah, K. (2019).Cerebellar modulation of the reward circuitry and social behavior. Science 363,eaav0581. doi:10.1126/science.aav0581

Cazenille, L., Collignon, B., Chemtob, Y., Bonnet, F., Gribovskiy, A., Mondada,F., Bredeche, N. and Halloy, J. (2018). How mimetic should a robotic fish be tosocially integrate into zebrafish groups? Bioinspir. Biomim. 13, 025001. doi:10.1088/1748-3190/aa8f6a

Chakravarty, S., Reddy, B. R., Sudhakar, S. R., Saxena, S., Das, T., Meghah, V.,Brahmendra Swamy, C. V., Kumar, A. and Idris, M. M. (2013). Chronicunpredictable stress (CUS)-induced anxiety and related mood disorders in azebrafish model: altered brain proteome profile implicates mitochondrialdysfunction. PLoS ONE 8, e63302. doi:10.1371/journal.pone.0063302

Chen, J., Tanguay, R. L., Simonich, M., Nie, S., Zhao, Y., Li, L., Bai, C., Dong, Q.,Huang, C. and Lin, K. (2016a). TBBPA chronic exposure produces sex-specificneurobehavioral and social interaction changes in adult zebrafish. Neurotoxicol.Teratol. 56, 9-15. doi:10.1016/j.ntt.2016.05.008

Chen, S., Chiu, C. N., Mcarthur, K. L., Fetcho, J. R. and Prober, D. A. (2016b).TRP channel mediated neuronal activation and ablation in freely behavingzebrafish. Nat. Methods 13, 147-150. doi:10.1038/nmeth.3691

Chiu, C. N., Rihel, J., Lee, D. A., Singh, C., Mosser, E. A., Chen, S., Sapin, V.,Pham, U., Engle, J., Niles, B. J. et al. (2016). A zebrafish genetic screenidentifies neuromedin U as a regulator of sleep/wake states. Neuron 89, 842-856.doi:10.1016/j.neuron.2016.01.007

Choi, J.-H., Jeong, Y.-M., Kim, S., Lee, B., Ariyasiri, K., Kim, H.-T., Jung, S.-H.,Hwang, K.-S., Choi, T.-I., Park, C. O. et al. (2018). Targeted knockout of achemokine-like gene increases anxiety and fear responses. Proc. Natl. Acad. Sci.USA 115, E1041-E1050. doi:10.1073/pnas.1707663115

Chou, M.-Y., Amo, R., Kinoshita, M., Cherng, B.-W., Shimazaki, H., Agetsuma,M., Shiraki, T., Aoki, T., Takahoko,M., Yamazaki, M. et al. (2016). Social conflictresolution regulated by two dorsal habenular subregions in zebrafish. Science352, 87-90. doi:10.1126/science.aac9508

Clark, D. A., Arranz, M. J., Mata, I., Lopez-Ilundain, J., Perez-Nievas, F. andKerwin, R. W. (2005). Polymorphisms in the promoter region of the alpha1A-adrenoceptor gene are associated with schizophrenia/schizoaffective disorder ina Spanish isolate population. Biol. Psychiatry 58, 435-439. doi:10.1016/j.biopsych.2005.04.051

Clark, D. A., Mancama, D., Kerwin, R. W. and Arranz, M. J. (2006). Expression ofthe alpha1A-adrenergic receptor in schizophrenia. Neurosci. Lett. 401, 248-251.doi:10.1016/j.neulet.2006.03.025

Clarke, A. and File, S. E. (1982). Selective neurotoxin lesions of the lateral septum:changes in social and aggressive behaviours. Pharmacol. Biochem. Behav. 17,623-628. doi:10.1016/0091-3057(82)90334-3

Clements, K. N., Miller, T. H., Keever, J. M., Hall, A. M. and Issa, F. A. (2018).Social status-related differences in motor activity between wild-type and mutantzebrafish. Biol. Bull. 235, 71-82. doi:10.1086/699514

Coe, T. S., Hamilton, P. B., Hodgson, D., Paull, G. C., Stevens, J. R., Sumner, K.and Tyler, C. R. (2008). An environmental estrogen alters reproductivehierarchies, disrupting sexual selection in group-spawning fish. Environ. Sci.Technol. 42, 5020-5025. doi:10.1021/es800277q

Coe, T. S., Hamilton, P. B., Hodgson, D., Paull, G. C. and Tyler, C. R. (2009).Parentage outcomes in response to estrogen exposure are modified by socialgrouping in zebrafish. Environ. Sci. Technol. 43, 8400-8405. doi:10.1021/es902302u

Colman, J. R., Baldwin, D., Johnson, L. L. and Scholz, N. L. (2009). Effects of thesynthetic estrogen, 17alpha-ethinylestradiol, on aggression and courtshipbehavior in male zebrafish (Danio rerio). Aquat. Toxicol. 91, 346-354. doi:10.1016/j.aquatox.2008.12.001

Cong, L., Wang, Z., Chai, Y., Hang,W., Shang, C., Yang,W., Bai, L., Du, J.,Wang,K. and Wen, Q. (2017). Rapid whole brain imaging of neural activity in freelybehaving larval zebrafish (Danio rerio). eLife 6, e28158. doi:10.7554/eLife.28158

Cronan, M. R., Rosenberg, A. F., Oehlers, S. H., Saelens, J. W., Sisk, D. M.,Jurcic Smith, K. L., Lee, S. and Tobin, D. M. (2015). CLARITY and PACT-basedimaging of adult zebrafish and mouse for whole-animal analysis of infections. Dis.Model. Mech. 8, 1643-1650. doi:10.1242/dmm.021394

Crosby, E. B., Bailey, J. M., Oliveri, A. N. and Levin, E. D. (2015). Neurobehavioralimpairments caused by developmental imidacloprid exposure in zebrafish.Neurotoxicol. Teratol. 49, 81-90. doi:10.1016/j.ntt.2015.04.006

Curado, S., Stainier, D. Y. R. and Anderson, R. M. (2008). Nitroreductase-mediated cell/tissue ablation in zebrafish: a spatially and temporally controlledablation method with applications in developmental and regeneration studies.Nat.Protoc. 3, 948-954. doi:10.1038/nprot.2008.58

Dang, M., Henderson, R. E., Garraway, L. A. and Zon, L. I. (2016). Long-term drugadministration in the adult zebrafish using oral gavage for cancer preclinicalstudies. Dis. Model. Mech. 9, 811-820. doi:10.1242/dmm.024166

Darrow, K. O. and Harris, W. A. (2004). Characterization and development ofcourtship in zebrafish, Danio rerio. Zebrafish 1, 40-45. doi:10.1089/154585404774101662

Deng, H., Xiao, X. and Wang, Z. (2016). Periaqueductal gray neuronal activitiesunderlie different aspects of defensive behaviors. J. Neurosci. 36, 7580-7588.doi:10.1523/JNEUROSCI.4425-15.2016

Dewari, P. S., Ajani, F., Kushawah, G., Kumar, D. S. and Mishra, R. K. (2016).Reversible loss of reproductive fitness in zebrafish on chronic alcohol exposure.Alcohol 50, 83-89. doi:10.1016/j.alcohol.2015.11.006

Dipp, V. R., Valles, S., Ortiz-Kerbertt, H., Suarez, J. V. and Bardullas, U. (2018).Neurobehavioral alterations in zebrafish due to long-term exposure to low doses ofinorganic arsenic. Zebrafish 15, 575-585. doi:10.1089/zeb.2018.1627

Dolen, G., Darvishzadeh, A., Huang, K. W. and Malenka, R. C. (2013). Socialreward requires coordinated activity of nucleus accumbens oxytocin andserotonin. Nature 501, 179-184. doi:10.1038/nature12518

Dreosti, E., Lopes, G., Kampff, A. R. and Wilson, S. W. (2015). Development ofsocial behavior in young zebrafish. Front. Neural Circuits 9, 39. doi:10.3389/fncir.2015.00039

Durand, C. M., Betancur, C., Boeckers, T. M., Bockmann, J., Chaste, P.,Fauchereau, F., Nygren, G., Rastam, M., Gillberg, I. C., Anckarsater, H. et al.(2007). Mutations in the gene encoding the synaptic scaffolding protein SHANK3are associated with autism spectrum disorders. Nat. Genet. 39, 25-27. doi:10.1038/ng1933

Dwivedi, S., Medishetti, R., Rani, R., Sevilimedu, A., Kulkarni, P. andYogeeswari, P. (2019). Larval zebrafish model for studying the effects ofvalproic acid on neurodevelopment: An approach towards modeling autism.J. Pharmacol. Toxicol. Methods 95, 56-65. doi:10.1016/j.vascn.2018.11.006

Eachus, H., Bright, C., Cunliffe, V. T., Placzek, M., Wood, J. D. and Watt, P. J.(2017). Disrupted-in-Schizophrenia-1 is essential for normal hypothalamic-pituitary-interrenal (HPI) axis function. Hum. Mol. Genet. 26, 1992-2005. doi:10.1093/hmg/ddx076

Eguiraun, H., Casquero, O., Sørensen, A. J. andMartinez, I. (2018). Reducing thenumber of individuals tomonitor shoaling fish systems - application of the shannonentropy to construct a biological warning system model. Front. Physiol. 9, 493.doi:10.3389/fphys.2018.00493

Engeszer, R. E., Ryan, M. J. and Parichy, D. M. (2004). Learned social preferencein zebrafish. Curr. Biol. 14, 881-884. doi:10.1016/j.cub.2004.04.042

Falkner, A. L. and Lin, D. (2014). Recent advances in understanding the role of thehypothalamic circuit during aggression. Front. Syst. Neurosci. 8, 168. doi:10.3389/fnsys.2014.00168

Fang, Y. Y., Yamaguchi, T., Song, S. C., Tritsch, N. X. and Lin, D. (2018). Ahypothalamic midbrain pathway essential for driving maternal behaviors. Neuron98, 192-207.e10. doi:10.1016/j.neuron.2018.02.019

Fantz, R. L. (1963). Pattern vision in newborn infants. Science 140, 296-297. doi:10.1126/science.140.3564.296

Felix, L. M., Antunes, L. M., Coimbra, A. M. and Valentim, A. M. (2017a).Behavioral alterations of zebrafish larvae after early embryonic exposure toketamine. Psychopharmacology (Berl.) 234, 549-558. doi:10.1007/s00213-016-4491-7

Felix, L.M., Serafim, C., Martins, M. J., Valentim, A.M., Antunes, L. M., Matos, M.and Coimbra, A. M. (2017b). Morphological and behavioral responses ofzebrafish after 24h of ketamine embryonic exposure. Toxicol. Appl. Pharmacol.321, 27-36. doi:10.1016/j.taap.2017.02.013

Fernandes, Y. and Gerlai, R. (2009). Long-term behavioral changes in response toearly developmental exposure to ethanol in zebrafish. Alcohol. Clin. Exp. Res. 33,601-609. doi:10.1111/j.1530-0277.2008.00874.x

Fernandes, Y., Rampersad, M. andGerlai, R. (2015). Embryonic alcohol exposureimpairs the dopaminergic system and social behavioral responses in adultzebrafish. Int. J. Neuropsychopharmacol. 18, pyu089. doi:10.1093/ijnp/pyu089

Ferrero, D. M., Moeller, L. M., Osakada, T., Horio, N., Li, Q., Roy, D. S., Cichy, A.,Spehr, M., Touhara, K. and Liberles, S. D. (2013). A juvenile mouse pheromoneinhibits sexual behaviour through the vomeronasal system. Nature 502, 368-371.doi:10.1038/nature12579

Filby, A. L., Paull, G. C., Bartlett, E. J., van Look, K. J.W. and Tyler, C. R. (2010a).Physiological and health consequences of social status in zebrafish (Danio rerio).Physiol. Behav. 101, 576-587. doi:10.1016/j.physbeh.2010.09.004

Filby, A. L., Paull, G. C., Hickmore, T. F. A. and Tyler, C. R. (2010b). Unravellingthe neurophysiological basis of aggression in a fish model. BMC Genomics 11,498. doi:10.1186/1471-2164-11-498

Filby, A. L., Paull, G. C., Searle, F., Ortiz-Zarragoitia, M. and Tyler, C. R. (2012).Environmental estrogen-induced alterations of male aggression and dominancehierarchies in fish: a mechanistic analysis. Environ. Sci. Technol. 46, 3472-3479.doi:10.1021/es204023d

Filiano, A. J., Xu, Y., Tustison, N. J., Marsh, R. L., Baker,W., Smirnov, I., Overall,C. C., Gadani, S. P., Turner, S. D., Weng, Z. et al. (2016). Unexpected role ofinterferon-gamma in regulating neuronal connectivity and social behaviour.Nature 535, 425-429. doi:10.1038/nature18626

Flanigan, M., Aleyasin, H., Takahashi, A., Golden, S. A. and Russo, S. J. (2017).An emerging role for the lateral habenula in aggressive behavior. Pharmacol.Biochem. Behav. 162, 79-86. doi:10.1016/j.pbb.2017.05.003

Fontana, B. D., Meinerz, D. L., Rosa, L. V. C., Mezzomo, N. J., Silveira, A.,Giuliani, G. S., Quadros, V. A., Filho, G. L. B., Blaser, R. E. and Rosemberg,D. B. (2016). Modulatory action of taurine on ethanol-induced aggressive

15

REVIEW Disease Models & Mechanisms (2019) 12, dmm039446. doi:10.1242/dmm.039446

Disea

seModels&Mechan

isms

behavior in zebrafish. Pharmacol. Biochem. Behav. 141, 18-27. doi:10.1016/j.pbb.2015.11.011

Fontana, B. D., Stefanello, F. V., Mezzomo, N. J., Muller, T. E., Quadros, V. A.,Parker, M. O., Rico, E. P. and Rosemberg, D. B. (2018). Taurine modulatesacute ethanol-induced social behavioral deficits and fear responses in adultzebrafish. J. Psychiatr. Res. 104, 176-182. doi:10.1016/j.jpsychires.2018.08.008

Forster, D., Dal Maschio, M., Laurell, E. and Baier, H. (2017). An optogenetictoolbox for unbiased discovery of functionally connected cells in neural circuits.Nat. Commun. 8, 116. doi:10.1038/s41467-017-00160-z

Franco-Restrepo, J. E., Forero, D. A. and Vargas, R. A. (2019). A review of freelyavailable, open-source software for the automated analysis of the behavior ofadult zebrafish. Zebrafish 16, 223-232. doi:10.1089/zeb.2018.1662

Frith, C. D. (2007). The social brain? Philos. Trans. R. Soc. Lond. B Biol. Sci. 362,671-678. doi:10.1098/rstb.2006.2003

Fulcher, N., Tran, S., Shams, S., Chatterjee, D. and Gerlai, R. (2017).Neurochemical and behavioral responses to unpredictable chronic mild stressfollowing developmental isolation: the zebrafish as a model for major depression.Zebrafish 14, 23-34. doi:10.1089/zeb.2016.1295

Gaugler, T., Klei, L., Sanders, S. J., Bodea, C. A., Goldberg, A. P., Lee, A. B.,Mahajan, M., Manaa, D., Pawitan, Y., Reichert, J. et al. (2014). Most genetic riskfor autism resides with common variation. Nat. Genet. 46, 881-885. doi:10.1038/ng.3039

Gerlach, G., Hodgins-Davis, A., Avolio, C. and Schunter, C. (2008). Kinrecognition in zebrafish: a 24-hour window for olfactory imprinting. Proc. Biol.Sci. 275, 2165-2170. doi:10.1098/rspb.2008.0647

Gerlach, G., Tietje, K., Biechl, D., Namekawa, I., Schalm, G. and Sulmann, A.(2019). Behavioural and neuronal basis of olfactory imprinting and kin recognitionin larval fish. J. Exp. Biol. 222, Suppl. 1, jeb189746. doi:10.1242/jeb.189746

Gerlai, R. (2017). Animated images in the analysis of zebrafish behavior. Curr Zool63, 35-44. doi:10.1093/cz/zow077

Giacomini, A. C. V. V., Abreu, M. S., Giacomini, L. V., Siebel, A. M., Zimerman,F. F., Rambo, C. L., Mocelin, R., Bonan, C. D., Piato, A. L. and Barcellos,L. J. G. (2016). Fluoxetine and diazepam acutely modulate stress induced-behavior. Behav. Brain Res. 296, 301-310. doi:10.1016/j.bbr.2015.09.027

Gierszewski, S., Muller, K., Smielik, I., Hutwohl, J.-M., Kuhnert, K.-D. andWitte,K. (2017). The virtual lover: variable and easily guided 3D fish animations as aninnovative tool in mate-choice experiments with sailfin mollies-II. Validation. Curr.Zool. 63, 65-74. doi:10.1093/cz/zow108

Gierszewski, S., Baker, D., Muller, K., Hutwohl, J. M., Kuhnert, K.-D. and Witte,K. (2018). Using the FishSim animation toolchain to investigate fish behavior: acase study on mate-choice copying in Sailfin Mollies. J. Vis. Exp. 141, e58435.doi:10.3791/58435

Glazer, L., Hawkey, A. B., Wells, C. N., Drastal, M., Odamah, K.-A., Behl, M. andLevin, E. D. (2018a). Developmental exposure to low concentrations oforganophosphate flame retardants causes life-long behavioral alterations inzebrafish. Toxicol. Sci. 165, 487-498. doi:10.1093/toxsci/kfy173

Glazer, L., Wells, C. N., Drastal, M., Odamah, K.-A., Galat, R. E., Behl, M. andLevin, E. D. (2018b). Developmental exposure to low concentrations of twobrominated flame retardants, BDE-47 and BDE-99, causes life-long behavioralalterations in zebrafish. Neurotoxicology 66, 221-232. doi:10.1016/j.neuro.2017.09.007

Golden, S. A., Heshmati, M., Flanigan, M., Christoffel, D. J., Guise, K., Pfau,M. L., Aleyasin, H., Menard, C., Zhang, H., Hodes, G. E. et al. (2016). Basalforebrain projections to the lateral habenula modulate aggression reward. Nature534, 688-692. doi:10.1038/nature18601

Golzio, C., Willer, J., Talkowski, M. E., Oh, E. C., Taniguchi, Y., Jacquemont, S.,Reymond, A., Sun, M., Sawa, A., Gusella, J. F. et al. (2012). KCTD13 is a majordriver of mirrored neuroanatomical phenotypes of the 16p11.2 copy numbervariant. Nature 485, 363-367. doi:10.1038/nature11091

Green, J., Collins, C., Kyzar, E. J., Pham, M., Roth, A., Gaikwad, S., Cachat, J.,Stewart, A. M., Landsman, S., Grieco, F. et al. (2012). Automated high-throughput neurophenotyping of zebrafish social behavior. J. Neurosci. Methods210, 266-271. doi:10.1016/j.jneumeth.2012.07.017

Grossman, L., Utterback, E., Stewart, A., Gaikwad, S., Chung, K. M., Suciu, C.,Wong, K., Elegante, M., Elkhayat, S., Tan, J. et al. (2010). Characterization ofbehavioral and endocrine effects of LSD on zebrafish. Behav. Brain Res. 214,277-284. doi:10.1016/j.bbr.2010.05.039

Guayasamin, O. L., Couzin, I. D. and Miller, N. Y. (2017). Behavioural plasticityacross social contexts is regulated by the directionality of inter-individualdifferences. Behav. Processes 141, 196-204. doi:10.1016/j.beproc.2016.10.004

Halloy, J., Sempo, G., Caprari, G., Rivault, C., Asadpour, M., Tache, F., Said, I.,Durier, V., Canonge, S., Ame, J. M. et al. (2007). Social integration of robots intogroups of cockroaches to control self-organized choices. Science 318,1155-1158. doi:10.1126/science.1144259

Hanell, A. and Marklund, N. (2014). Structured evaluation of rodent behavioraltests used in drug discovery research. Front. Behav. Neurosci. 8, 252. doi:10.3389/fnbeh.2014.00252

Harpaz, R., Tka�cik, G. and Schneidman, E. (2017). Discrete modes of socialinformation processing predict individual behavior of fish in a group. Proc. Natl.Acad. Sci. USA 114, 10149-10154. doi:10.1073/pnas.1703817114

Hashikawa, K., Hashikawa, Y., Tremblay, R., Zhang, J., Feng, J. E., Sabol, A.,Piper, W. T., Lee, H., Rudy, B. and Lin, D. (2017). Esr1(+) cells in theventromedial hypothalamus control female aggression. Nat. Neurosci. 20,1580-1590. doi:10.1038/nn.4644

Heap, L. A., Goh, C. C., Kassahn, K. S. and Scott, E. K. (2013). Cerebellar outputin zebrafish: an analysis of spatial patterns and topography in eurydendroid cellprojections. Front. Neural Circuits 7, 53. doi:10.3389/fncir.2013.00053

Heras, F. J. H., Romero-Ferrero, F., Hinz, R. C. and de Polavieja, G. G. (2018).Deep attention networks reveal the rules of collective motion in zebrafish. bioRxiv.doi:10.1101/400747

Hinz, R. C. and de Polavieja, G. G. (2017). Ontogeny of collective behavior revealsa simple attraction rule. Proc. Natl. Acad. Sci. USA 114, 2295-2300. doi:10.1073/pnas.1616926114

Hinz, C., Kobbenbring, S., Kress, S., Sigman, L., Muller, A. and Gerlach, G.(2013). Kin recognition in zebrafish, Danio rerio, is based on imprinting onolfactory and visual stimuli. Anim. Behav. 85, 925-930. doi:10.1016/j.anbehav.2013.02.010

Hitti, F. L. and Siegelbaum, S. A. (2014). The hippocampal CA2 region is essentialfor social memory. Nature 508, 88-92. doi:10.1038/nature13028

Hoffman, E. J., Turner, K. J., Fernandez, J. M., Cifuentes, D., Ghosh, M., Ijaz, S.,Jain, R. A., Kubo, F., Bill, B. R., Baier, H. et al. (2016). Estrogens suppress abehavioral phenotype in zebrafish mutants of the autism risk gene, CNTNAP2.Neuron 89, 725-733. doi:10.1016/j.neuron.2015.12.039

Huang, K., Shi, Y., Tang, W., Tang, R., Guo, S., Xu, Y., Meng, J., Li, X., Feng, G.and He, L. (2008). No association found between the promoter variants ofADRA1A and schizophrenia in the Chinese population. J. Psychiatr. Res. 42,384-388. doi:10.1016/j.jpsychires.2007.02.008

Hung, L. W., Neuner, S., Polepalli, J. S., Beier, K. T., Wright, M., Walsh, J. J.,Lewis, E. M., Luo, L., Deisseroth, K., Dolen, G. and et al. (2017). Gating of socialreward by oxytocin in the ventral tegmental area.Science 357, 1406-1411. doi:10.1126/science.aan4994

Huntingford, F. and Turner, A. K. (1987). Animal conflict. London; New York:Chapman and Hall.

Hwang, W. Y., Fu, Y., Reyon, D., Maeder, M. L., Tsai, S. Q., Sander, J. D.,Peterson, R. T., Yeh, J.-R. J. and Joung, J. K. (2013). Efficient genome editing inzebrafish using a CRISPR-Cas system. Nat. Biotechnol. 31, 227-229. doi:10.1038/nbt.2501

Jacquet, H., Demily, C., Houy, E., Hecketsweiler, B., Bou, J., Raux, G., Lerond,J., Allio, G., Haouzir, S., Tillaux, A. et al. (2005). Hyperprolinemia is a risk factorfor schizoaffective disorder. Mol. Psychiatry 10, 479-485. doi:10.1038/sj.mp.4001597

Jetti, S. K., Vendrell-Llopis, N. and Yaksi, E. (2014). Spontaneous activity governsolfactory representations in spatially organized habenular microcircuits.Curr. Biol.24, 434-439. doi:10.1016/j.cub.2014.01.015

Jolous-Jamshidi, B., Cromwell, H. C., Mcfarland, A. M. and Meserve, L. A.(2010). Perinatal exposure to polychlorinated biphenyls alters social behaviors inrats. Toxicol. Lett. 199, 136-143. doi:10.1016/j.toxlet.2010.08.015

Jordi, J., Guggiana-Nilo, D., Bolton, A. D., Prabha, S., Ballotti, K., Herrera, K.,Rennekamp, A. J., Peterson, R. T., Lutz, T. A. and Engert, F. (2018). High-throughput screening for selective appetite modulators: a multibehavioral andtranslational drug discovery strategy. Sci. Adv. 4, eaav1966. doi:10.1126/sciadv.aav1966

Katz, Y., Tunstrom, K., Ioannou, C. C., Huepe, C. and Couzin, I. D. (2011).Inferring the structure and dynamics of interactions in schooling fish. Proc. Natl.Acad. Sci. USA 108, 18720-18725. doi:10.1073/pnas.1107583108

Kim, D. H., Kim, J., Marques, J. C., Grama, A., Hildebrand, D. G. C., Gu, W., Li,J. M. and Robson, D. N. (2017a). Pan-neuronal calcium imaging with cellularresolution in freely swimming zebrafish. Nat. Methods 14, 1107-1114. doi:10.1038/nmeth.4429

Kim, O.-H., Cho, H.-J., Han, E., Hong, T. I., Ariyasiri, K., Choi, J.-H., Hwang, K.-S., Jeong, Y.-M., Yang, S.-Y., Yu, K. et al. (2017b). Zebrafish knockout of Downsyndrome gene, DYRK1a, shows social impairments relevant to autism. Mol.Autism 8, 50. doi:10.1186/s13229-017-0168-2

Kirsten, K., Soares, S. M., Koakoski, G., Carlos Kreutz, L. and Barcellos, L. J. G.(2018). Characterization of sickness behavior in zebrafish. Brain Behav. Immun.73, 596-602. doi:10.1016/j.bbi.2018.07.004

Knecht, A. L., Truong, L., Marvel, S. W., Reif, D. M., Garcia, A., Lu, C., Simonich,M. T., Teeguarden, J. G. and Tanguay, R. L. (2017). Transgenerationalinheritance of neurobehavioral and physiological deficits from developmentalexposure to benzo[a]pyrene in zebrafish. Toxicol. Appl. Pharmacol. 329, 148-157.doi:10.1016/j.taap.2017.05.033

Kokel, D., Bryan, J., Laggner, C., White, R., Cheung, C. Y. J., Mateus, R., Healey,D., Kim, S., Werdich, A. A., Haggarty, S. J. et al. (2010). Rapid behavior-basedidentification of neuroactive small molecules in the zebrafish. Nat. Chem. Biol. 6,231-237. doi:10.1038/nchembio.307

Kokel, D., Rennekamp, A. J., Shah, A. H., Liebel, U. and Peterson, R. T. (2012).Behavioral barcoding in the cloud: embracing data-intensive digital phenotyping inneuropharmacology. Trends Biotechnol. 30, 421-425. doi:10.1016/j.tibtech.2012.05.001

16

REVIEW Disease Models & Mechanisms (2019) 12, dmm039446. doi:10.1242/dmm.039446

Disea

seModels&Mechan

isms

Kopman, V., Laut, J., Polverino, G. and Porfiri, M. (2013). Closed-loop control ofzebrafish response using a bioinspired robotic-fish in a preference test. J. R Soc.Interface 10, 20120540. doi:10.1098/rsif.2012.0540

Kraus, T., Haack, M., Schuld, A., Hinze-Selch, D. and Pollmacher, T. (2001). Lowleptin levels but normal body mass indices in patients with depression orschizophrenia. Neuroendocrinology 73, 243-247. doi:10.1159/000054641

Krause, J. and Ruxton, G. D. (2002). Living in Groups. Oxford, New York: OxfordUniversity Press.

Kulkarni, P., Chaudhari, G. H., Sripuram, V., Banote, R. K., Kirla, K. T., Sultana,R., Rao, P., Oruganti, S. and Chatti, K. (2014). Oral dosing in adult zebrafish:proof-of-concept using pharmacokinetics and pharmacological evaluation ofcarbamazepine. Pharmacol. Rep. 66, 179-183. doi:10.1016/j.pharep.2013.06.012

Kuroda, T. (2018). A system for the real-time tracking of operant behavior as anapplication of 3D camera. J. Exp. Anal. Behav. 110, 522-544. doi:10.1002/jeab.471

Laan, A., Gil de Sagredo, R. and de Polavieja, G. G. (2017). Signatures of optimalcontrol in pairs of schooling zebrafish. Proc. Biol. Sci. 284, 20170224. doi:10.1098/rspb.2017.0224

Laan, A., Iglesias-Julios, M. and de Polavieja, G. G. (2018). Zebrafish aggressionon the sub-second time scale: evidence for mutual motor coordination and multi-functional attack manoeuvres. R. Soc. Open Sci. 5, 180679. doi:10.1098/rsos.180679

Lam, P.-Y., Mendu, S. K., Mills, R. W., Zheng, B., Padilla, H., Milan, D. J., Desai,B. N. and Peterson, R. T. (2017). A high-conductance chemo-optogeneticsystem based on the vertebrate channel Trpa1b. Sci. Rep. 7, 11839. doi:10.1038/s41598-017-11791-z

Lambert, C. J., Freshner, B. C., Chung, A., Stevenson, T. J., Bowles, D. M.,Samuel, R., Gale, B. K. and Bonkowsky, J. L. (2018). An automated system forrapid cellular extraction from live zebrafish embryos and larvae: development andapplication to genotyping. PLoS ONE 13, e0193180. doi:10.1371/journal.pone.0193180

Lan, A., Kalimian, M., Amram, B. and Kofman, O. (2017). Prenatal chlorpyrifosleads to autism-like deficits in C57Bl6/J mice. Environ. Health 16, 43. doi:10.1186/s12940-017-0251-3

Larsch, J. and Baier, H. (2018). Biological motion as an innate perceptualmechanism driving social affiliation. Curr. Biol. 28, 3523-3532.e4. doi:10.1016/j.cub.2018.09.014

Larson, E. T., O’Malley, D. M. and Melloni, R. H.Jr. (2006). Aggression andvasotocin are associated with dominant-subordinate relationships in zebrafish.Behav. Brain Res. 167, 94-102. doi:10.1016/j.bbr.2005.08.020

Lebow, M. A. and Chen, A. (2016). Overshadowed by the amygdala: the bednucleus of the stria terminalis emerges as key to psychiatric disorders. Mol.Psychiatry 21, 450-463. doi:10.1038/mp.2016.1

Leroy, F., Park, J., Asok, A., Brann, D. H., Meira, T., Boyle, L. M., Buss, E. W.,Kandel, E. R. and Siegelbaum, S. A. (2018). A circuit from hippocampal CA2 tolateral septum disinhibits social aggression. Nature 564, 213-218. doi:10.1038/s41586-018-0772-0

Li, X., Guo, J.-Y., Li, X., Zhou, H.-J., Zhang, S.-H., Liu, X.-D., Chen, D.-Y., Fang,Y.-C. and Feng, X.-Z. (2017a). Behavioural effect of low-dose BPA on malezebrafish: Tuning of male mating competition and female mating preferenceduring courtship process. Chemosphere 169, 40-52. doi:10.1016/j.chemosphere.2016.11.053

Li, Y., Mathis, A., Grewe, B. F., Osterhout, J. A., Ahanonu, B., Schnitzer, M. J.,Murthy, V. N. and Dulac, C. (2017b). Neuronal representation of socialinformation in the medial amygdala of awake behaving mice. Cell 171,1176-1190.e17. doi:10.1016/j.cell.2017.10.015

Lindeyer, C. M. and Reader, S. M. (2010). Social learning of escape routes inzebrafish and the stability of behavioural traditions. Anim. Behav. 79, 827-834.doi:10.1016/j.anbehav.2009.12.024

Lister, J. A., Robertson, C. P., Lepage, T., Johnson, S. L. and Raible, D. W.(1999). nacre encodes a zebrafish microphthalmia-related protein that regulatesneural-crest-derived pigment cell fate. Development 126, 3757-3767.

Liu, C.-X., Li, C.-Y., Hu, C.-C., Wang, Y., Lin, J., Jiang, Y.-H., Li, Q. and Xu, X.(2018a). CRISPR/Cas9-induced shank3b mutant zebrafish display autism-likebehaviors. Mol. Autism 9, 23. doi:10.1186/s13229-018-0204-x

Liu, J., Sun, L., Zhang, H., Shi, M., Dahlgren, R. A., Wang, X. and Wang, H.(2018b). Response mechanisms to joint exposure of triclosan and its chlorinatedderivatives on zebrafish (Danio rerio) behavior. Chemosphere 193, 820-832.doi:10.1016/j.chemosphere.2017.11.106

Lopes, J. S., Abril-de-Abreu, R. and Oliveira, R. F. (2015). Brain transcriptomicresponse to social eavesdropping in zebrafish (Danio rerio). PLoS ONE 10,e0145801. doi:10.1371/journal.pone.0145801

Lord, C., Cook, E. H., Leventhal, B. L. and Amaral, D. G. (2000). Autism spectrumdisorders. Neuron 28, 355-363. doi:10.1016/S0896-6273(00)00115-X

Lyall, K., Croen, L. A., Sjodin, A., Yoshida, C. K., Zerbo, O., Kharrazi, M. andWindham, G. C. (2017). Polychlorinated biphenyl and organochlorine pesticideconcentrations in maternal mid-pregnancy serum samples: association withautism spectrum disorder and intellectual disability. Environ. Health Perspect.125, 474-480. doi:10.1289/EHP277

Maaswinkel, H., Zhu, L. and Weng, W. (2013a). Assessing social engagement inheterogeneous groups of zebrafish: a new paradigm for autism-like behavioralresponses. PLoS ONE 8, e75955. doi:10.1371/journal.pone.0075955

Maaswinkel, H., Zhu, L. and Weng, W. (2013b). Using an automated 3D-trackingsystem to record individual and shoals of adult zebrafish. J. Vis. Exp. 82, e50681.doi:10.3791/50681

Mackay, D., Hughes, D. M., Romano, M. L. and Bonnell, M. (2014). The role ofpersistence in chemical evaluations. Integr. Environ. Assess. Manag. 10,588-594. doi:10.1002/ieam.1545

Macrì, S., Neri, D., Ruberto, T., Mwaffo, V., Butail, S. and Porfiri, M. (2017). Three-dimensional scoring of zebrafish behavior unveils biological phenomena hidden bytwo-dimensional analyses. Sci. Rep. 7, 1962. doi:10.1038/s41598-017-01990-z

Madeira, N. and Oliveira, R. F. (2017). Long-term social recognition memory inzebrafish. Zebrafish 14, 305-310. doi:10.1089/zeb.2017.1430

Madirolas, G. and de Polavieja, G. G. (2015). Improving collective estimationsusing resistance to social influence. PLoS Comput. Biol. 11, e1004594. doi:10.1371/journal.pcbi.1004594

Malki, K., du Rietz, E., Crusio, W. E., Pain, O., Paya-Cano, J., Karadaghi, R. L.,Sluyter, F., DE Boer, S. F., Sandnabba, K., Schalkwyk, L. C. et al. (2016).Transcriptome analysis of genes and gene networks involved in aggressivebehavior in mouse and zebrafish. Am. J. Med. Genet. B Neuropsychiatr. Genet.171, 827-838. doi:10.1002/ajmg.b.32451

Marques, J. C., Lackner, S., Felix, R. and Orger, M. B. (2018). Structure of thezebrafish locomotor repertoire revealed with unsupervised behavioral clustering.Curr. Biol. 28, 181-195.e5. doi:10.1016/j.cub.2017.12.002

Maruska, K., Soares, M. C., Lima-Maximino, M., Henrique de Siqueira-Silva, D.and Maximino, C. (2019). Social plasticity in the fish brain: neuroscientific andethological aspects. Brain Res. 1711, 156-172. doi:10.20944/preprints201809.0279.v2

Matthews, G. A., Nieh, E. H., Vander Weele, C. M., Halbert, S. A., Pradhan, R. V.,Yosafat, A. S., Glober, G. F., Izadmehr, E. M., Thomas, R. E., Lacy, G. D. et al.(2016). Dorsal Raphe dopamine neurons represent the experience of socialisolation. Cell 164, 617-631. doi:10.1016/j.cell.2015.12.040

Mccutcheon, V., Park, E., Liu, E., Sobhebidari, P., Tavakkoli, J., Wen, X.-Y. andBaker, A. J. (2017). A novel model of traumatic brain injury in adult zebrafishdemonstrates response to injury and treatment comparable with mammalianmodels. J. Neurotrauma 34, 1382-1393. doi:10.1089/neu.2016.4497

Mchenry, J. A., Otis, J. M., Rossi, M. A., Robinson, J. E., Kosyk, O., Miller, N. W.,Mcelligott, Z. A., Budygin, E. A., Rubinow, D. R. and Stuber, G. D. (2017).Hormonal gain control of a medial preoptic area social reward circuit. Nat.Neurosci. 20, 449-458. doi:10.1038/nn.4487

Meira, T., Leroy, F., Buss, E. W., Oliva, A., Park, J. and Siegelbaum, S. A. (2018).A hippocampal circuit linking dorsal CA2 to ventral CA1 critical for social memorydynamics. Nat. Commun. 9, 4163. doi:10.1038/s41467-018-06501-w

Miller, N. and Gerlai, R. (2007). Quantification of shoaling behaviour in zebrafish(Danio rerio). Behav. Brain Res. 184, 157-166. doi:10.1016/j.bbr.2007.07.007

Miller, N., Greene, K., Dydinski, A. and Gerlai, R. (2013). Effects of nicotine andalcohol on zebrafish (Danio rerio) shoaling. Behav. Brain Res. 240, 192-196.doi:10.1016/j.bbr.2012.11.033

Morrison, C. D. (2009). Leptin signaling in brain: a link between nutrition andcognition? Biochim. Biophys. Acta 1792, 401-408. doi:10.1016/j.bbadis.2008.12.004

Mullen, B. R., Khialeeva, E., Hoffman, D. B., Ghiani, C. A. and Carpenter, E. M.(2012). Decreased reelin expression and organophosphate pesticide exposurealters mouse behaviour and brain morphology. ASN Neuro 5, e00106. doi:10.1042/AN20120060

Muller, K., Smielik, I., Hutwohl, J.-M., Gierszewski, S., Witte, K. and Kuhnert, K.-D. (2017a). The virtual lover: variable and easily guided 3D fish animations as aninnovative tool in mate-choice experiments with sailfin mollies-I. Design andimplementation. Curr. Zool. 63, 55-64. doi:10.1093/cz/zow106

Muller, T. E., Nunes, S. Z., Silveira, A., Loro, V. L. and Rosemberg, D. B. (2017b).Repeated ethanol exposure alters social behavior and oxidative stressparameters of zebrafish. Prog. Neuropsychopharmacol. Biol. Psychiatry 79,105-111. doi:10.1016/j.pnpbp.2017.05.026

Muto, A. and Kawakami, K. (2016). Calcium imaging of neuronal activity in free-swimming larval zebrafish.Methods Mol. Biol. 1451, 333-341. doi:10.1007/978-1-4939-3771-4_23

Mwaffo, V., Butail, S. and Porfiri, M. (2017). In-silico experiments of zebrafishbehaviour: modeling swimming in three dimensions. Sci. Rep. 7, 39877. doi:10.1038/srep39877

Newman, S. W. (1999). The medial extended amygdala in male reproductivebehavior a node in the mammalian social behavior network. Ann. N. Y. Acad. Sci.877, 242-257. doi:10.1111/j.1749-6632.1999.tb09271.x

Nomoto, K. and Lima, S. Q. (2015). Enhanced male-evoked responses in theventromedial hypothalamus of sexually receptive female mice. Curr. Biol. 25,589-594. doi:10.1016/j.cub.2014.12.048

Norton, W. H. J., Stumpenhorst, K., Faus-Kessler, T., Folchert, A., Rohner, N.,Harris, M. P., Callebert, J. and Bally-Cuif, L. (2011). Modulation of Fgfr1asignaling in zebrafish reveals a genetic basis for the aggression-boldness

17

REVIEW Disease Models & Mechanisms (2019) 12, dmm039446. doi:10.1242/dmm.039446

Disea

seModels&Mechan

isms

syndrome. J. Neurosci. 31, 13796-13807. doi:10.1523/JNEUROSCI.2892-11.2011

O’Connell, L. A. and Hofmann, H. A. (2011a). Genes, hormones, and circuits: anintegrative approach to study the evolution of social behavior. Front.Neuroendocrinol. 32, 320-335. doi:10.1016/j.yfrne.2010.12.004

O’Connell, L. A. and Hofmann, H. A. (2011b). The vertebrate mesolimbic rewardsystem and social behavior network: a comparative synthesis. J. Comp. Neurol.519, 3599-3639. doi:10.1002/cne.22735

O’Connell, L. A. and Hofmann, H. A. (2012). Evolution of a vertebrate socialdecision-making network. Science 336, 1154-1157. doi:10.1126/science.1218889

Okuyama, T., Kitamura, T., Roy, D. S., Itohara, S. and Tonegawa, S. (2016).Ventral CA1 neurons store social memory. Science 353, 1536-1541. doi:10.1126/science.aaf7003

Oliveira, R. F., Simões, J. M., Teles, M. C., Oliveira, C. R., Becker, J. D. andLopes, J. S. (2016). Assessment of fight outcome is needed to activate sociallydriven transcriptional changes in the zebrafish brain. Proc. Natl. Acad. Sci. USA113, E654-E661. doi:10.1073/pnas.1514292113

Oliveri, A. N., Bailey, J. M. and Levin, E. D. (2015). Developmental exposure toorganophosphate flame retardants causes behavioral effects in larval and adultzebrafish. Neurotoxicol. Teratol. 52, 220-227. doi:10.1016/j.ntt.2015.08.008

Oresi�c, M., Tang, J., Seppanen-Laakso, T., Mattila, I., Saarni, S. E., Saarni, S. I.,Lonnqvist, J., Sysi-Aho, M., Hyotylainen, T., Perala, J. and et al. (2011).Metabolome in schizophrenia and other psychotic disorders: a generalpopulation-based study. Genome Med. 3, 19. doi:10.1186/gm233

Patowary, A., Won, S. Y., Oh, S. J., Nesbitt, R. R., Archer, M., Nickerson, D.,Raskind, W. H., Bernier, R., Lee, J. E. and Brkanac, Z. (2019). Family-basedexome sequencing and case-control analysis implicate CEP41 as an ASD gene.Transl. Psychiatry 9, 4. doi:10.1038/s41398-018-0343-z

Paull, G. C., Filby, A. L., Giddins, H. G., Coe, T. S., Hamilton, P. B. and Tyler,C. R. (2010). Dominance hierarchies in zebrafish (Danio rerio) and theirrelationship with reproductive success. Zebrafish 7, 109-117. doi:10.1089/zeb.2009.0618

Pavlidis, M., Sundvik, M., Chen, Y.-C. and Panula, P. (2011). Adaptive changes inzebrafish brain in dominant-subordinate behavioral context. Behav. Brain Res.225, 529-537. doi:10.1016/j.bbr.2011.08.022

Perathoner, S., Cordero-Maldonado, M. L. and Crawford, A. D. (2016). Potentialof zebrafish as amodel for exploring the role of the amygdala in emotional memoryand motivational behavior. J. Neurosci. Res. 94, 445-462. doi:10.1002/jnr.23712

Perez-Escudero, A., Vicente-Page, J., Hinz, R. C., Arganda, S. and de Polavieja,G. G. (2014). idTracker: tracking individuals in a group by automatic identificationof unmarked animals. Nat. Methods 11, 743-748. doi:10.1038/nmeth.2994

Petek, E., Windpassinger, C., Vincent, J. B., Cheung, J., Boright, A. P., Scherer,S.W., Kroisel, P. M. andWagner, K. (2001). Disruption of a novel gene (IMMP2L)by a breakpoint in 7q31 associated with Tourette syndrome. Am. J. Hum. Genet.68, 848-858. doi:10.1086/319523

Piato, Â. L., Capiotti, K. M., Tamborski, A. R., Oses, J. P., Barcellos, L. J. G.,Bogo, M. R., Lara, D. R., Vianna, M. R. and Bonan, C. D. (2011). Unpredictablechronic stress model in zebrafish (Danio rerio): behavioral and physiologicalresponses. Prog. Neuropsychopharmacol. Biol. Psychiatry 35, 561-567. doi:10.1016/j.pnpbp.2010.12.018

Polverino, G., Abaid, N., Kopman, V., Macrì, S. and Porfiri, M. (2012). Zebrafishresponse to robotic fish: preference experiments on isolated individuals and smallshoals. Bioinspir. Biomim. 7, 036019. doi:10.1088/1748-3182/7/3/036019

Ponzoni, L., Sala, M. and Braida, D. (2016). Ritanserin-sensitive receptorsmodulate the prosocial and the anxiolytic effect of MDMA derivatives, DOB andPma, in zebrafish. Behav. Brain Res. 314, 181-189. doi:10.1016/j.bbr.2016.08.009

Porfiri, M. and Ruiz Marın, M. (2017). Symbolic dynamics of animal interaction.J. Theor. Biol. 435, 145-156. doi:10.1016/j.jtbi.2017.09.005

Prykhozhij, S. V. and Berman, J. N. (2018). Zebrafish knock-ins swim into themainstream. Dis. Model. Mech. 11, dmm037515. doi:10.1242/dmm.037515

Prykhozhij, S. V., Steele, S. L., Razaghi, B. and Berman, J. N. (2017). A rapid andeffectivemethod for screening, sequencing and reporter verification of engineeredframeshift mutations in zebrafish. Dis. Model. Mech. 10, 811-822. doi:10.1242/dmm.026765

Qi, C.-C., Wang, Q.-J., Ma, X.-Z., Chen, H.-C., Gao, L.-P., Yin, J. and Jing, Y.-H.(2018). Interaction of basolateral amygdala, ventral hippocampus and medialprefrontal cortex regulates the consolidation and extinction of social fear. Behav.Brain. Funct. 14, 7. doi:10.1186/s12993-018-0139-6

Qian, Z.-M. and Chen, Y. Q. (2017). Feature point based 3D tracking of multiple fishfrom multi-view images. PLoS ONE 12, e0180254. doi:10.1371/journal.pone.0180254

Qian, Z.-M., Cheng, X. E. and Chen, Y. Q. (2014). Automatically detect and trackmultiple fish swimming in shallow water with frequent occlusion. PLoS ONE 9,e106506. doi:10.1371/journal.pone.0106506

Qian, Z.-M., Wang, S. H., Cheng, X. E. and Chen, Y. Q. (2016). An effective androbust method for tracking multiple fish in video image based on fish headdetection. BMC Bioinformatics 17, 251. doi:10.1186/s12859-016-1138-y

Raghavan, R., Zuckerman, B., Hong, X., Wang, G., Ji, Y., Paige, D., Dibari, J.,Zhang, C., Fallin, M. D. and Wang, X. (2018). Fetal and infancy growth pattern,cord and early childhood plasma leptin, and development of autism spectrumdisorder in the Boston birth cohort. Autism Res. 11, 1416-1431. doi:10.1002/aur.2011

Rennekamp, A. J. and Peterson, R. T. (2015). 15 years of zebrafish chemicalscreening. Curr. Opin. Chem. Biol. 24, 58-70. doi:10.1016/j.cbpa.2014.10.025

Riehl, R., Kyzar, E., Allain, A., Green, J., Hook, M., Monnig, L., Rhymes, K.,Roth, A., Pham, M., Razavi, R. et al. (2011). Behavioral and physiological effectsof acute ketamine exposure in adult zebrafish. Neurotoxicol. Teratol. 33, 658-667.doi:10.1016/j.ntt.2011.05.011

Rihel, J., Prober, D. A., Arvanites, A., Lam, K., Zimmerman, S., Jang, S.,Haggarty, S. J., Kokel, D., Rubin, L. L., Peterson, R. T. and et al. (2010).Zebrafish behavioral profiling links drugs to biological targets and rest/wakeregulation. Science 327, 348-351. doi:10.1126/science.1183090

Romero-Ferrero, F., Bergomi, M. G., Hinz, R. C., Heras, F. J. H. and de Polavieja,G. G. (2019). idtracker.ai: tracking all individuals in small or large collectives ofunmarked animals. Nat. Methods 16, 179-182. doi:10.1038/s41592-018-0295-5

Rosenthal, S. B., Twomey, C. R., Hartnett, A. T., Wu, H. S. and Couzin, I. D.(2015). Revealing the hidden networks of interaction in mobile animal groupsallows prediction of complex behavioral contagion. Proc. Natl. Acad. Sci. USA112, 4690-4695. doi:10.1073/pnas.1420068112

Roy, T. and Bhat, A. (2017). Social learning in a maze? Contrasting individualperformance among wild zebrafish when associated with trained and naïveconspecifics. Behav. Processes 144, 51-57. doi:10.1016/j.beproc.2017.09.004

Ruberto, T., Mwaffo, V., Singh, S., Neri, D. and Porfiri, M. (2016). Zebrafishresponse to a robotic replica in three dimensions. R Soc Open Sci 3, 160505.doi:10.1098/rsos.160505

Ruberto, T., Polverino, G. and Porfiri, M. (2017). How different is a 3D-printedreplica from a conspecific in the eyes of a zebrafish?. J. Exp. Anal. Behav. 107,279-293. doi:10.1002/jeab.247

Samaee, S.-M., Seyedin, S. and Varga, Z. M. (2017). An affordable intraperitonealinjection setup for juvenile and adult zebrafish. Zebrafish 14, 77-79. doi:10.1089/zeb.2016.1322

Sarasamma, S., Audira, G., Juniardi, S., Sampurna, B. P., Liang, S.-T., Hao, E.,Lai, Y.-H. and Hsiao, C.-D. (2018). Zinc chloride exposure inhibits brainacetylcholine levels, produces neurotoxic signatures, and diminishes memoryand motor activities in adult zebrafish. Int. J. Mol. Sci. 19, 3195. doi:10.3390/ijms19103195

Savio, L. E. B., Vuaden, F. C., Piato, A. L., Bonan, C. D. andWyse, A. T. S. (2012).Behavioral changes induced by long-term proline exposure are reversed byantipsychotics in zebrafish. Prog. Neuropsychopharmacol. Biol. Psychiatry 36,258-263. doi:10.1016/j.pnpbp.2011.10.002

Scerbina, T., Chatterjee, D. and Gerlai, R. (2012). Dopamine receptor antagonismdisrupts social preference in zebrafish: a strain comparison study. Amino Acids43, 2059-2072. doi:10.1007/s00726-012-1284-0

Schaefer, I. C., Siebel, A. M., Piato, A. L., Bonan, C. D., Vianna, M. R. and Lara,D. R. (2015). The side-by-side exploratory test: a simple automated protocol forthe evaluation of adult zebrafish behavior simultaneously with social interaction.Behav. Pharmacol. 26, 691-696. doi:10.1097/FBP.0000000000000145

Schirmer, A., Jesuthasan, S. and Mathuru, A. S. (2013). Tactile stimulationreduces fear in fish. Front. Behav. Neurosci. 7, 167. doi:10.3389/fnbeh.2013.00167

Schmidel, A. J., Assmann, K. L., Werlang, C. C., Bertoncello, K. T., Francescon,F., Rambo, C. L., Beltrame, G. M., Calegari, D., Batista, C. B., Blaser, R. E.et al. (2014). Subchronic atrazine exposure changes defensive behaviour profileand disrupts brain acetylcholinesterase activity of zebrafish.Neurotoxicol. Teratol.44, 62-69. doi:10.1016/j.ntt.2014.05.006

Sebat, J., Lakshmi, B., Malhotra, D., Troge, J., Lese-Martin, C., Walsh, T.,Yamrom, B., Yoon, S., Krasnitz, A., Kendall, J. et al. (2007). Strong associationof de novo copy number mutations with autism. Science 316, 445-449. doi:10.1126/science.1138659

Seguin, D. and Gerlai, R. (2018). Fetal alcohol spectrum disorders: zebrafish in theanalysis of the milder and more prevalent form of the disease. Behav. Brain Res.352, 125-132. doi:10.1016/j.bbr.2017.10.005

Seibt, K. J., Piato, A. L., da Luz Oliveira, R., Capiotti, K. M., Vianna, M. R. andBonan, C. D. (2011). Antipsychotic drugs reverse MK-801-induced cognitive andsocial interaction deficits in zebrafish (Danio rerio). Behav. Brain Res. 224,135-139. doi:10.1016/j.bbr.2011.05.034

Shah, A. N., Davey, C. F., Whitebirch, A. C., Miller, A. C. andMoens, C. B. (2015).Rapid reverse genetic screening using CRISPR in zebrafish. Nat. Methods 12,535-540. doi:10.1038/nmeth.3360

Shams, S., Amlani, S., Buske, C., Chatterjee, D. and Gerlai, R. (2018).Developmental social isolation affects adult behavior, social interaction, anddopaminemetabolite levels in zebrafish.Dev. Psychobiol. 60, 43-56. doi:10.1002/dev.21581

Shelton, D. S., Price, B. C., Ocasio, K. M. and Martins, E. P. (2015). Density andgroup size influence shoal cohesion, but not coordination in zebrafish (Daniorerio). J. Comp. Psychol. 129, 72-77. doi:10.1037/a0038382

18

REVIEW Disease Models & Mechanisms (2019) 12, dmm039446. doi:10.1242/dmm.039446

Disea

seModels&Mechan

isms

Shin, S., Pribiag, H., Lilascharoen, V., Knowland, D., Wang, X.-Y. and Lim, B. K.(2018). Drd3 signaling in the lateral septum mediates early life stress-inducedsocial dysfunction. Neuron 97, 195-208.e6. doi:10.1016/j.neuron.2017.11.040

Smith, K. S., Tindell, A. J., Aldridge, J. W. and Berridge, K. C. (2009). Ventralpallidum roles in reward and motivation. Behav. Brain Res. 196, 155-167. doi:10.1016/j.bbr.2008.09.038

Sneddon, L. U., Schmidt, R., Fang, Y. and Cossins, A. R. (2011). Molecularcorrelates of social dominance: a novel role for ependymin in aggression. PLoSONE 6, e18181. doi:10.1371/journal.pone.0018181

Stednitz, S. J., Mcdermott, E. M., Ncube, D., Tallafuss, A., Eisen, J. S. andWashbourne, P. (2018). Forebrain control of behaviorally driven social orientingin zebrafish. Curr. Biol. 28, 2445-2451.e3. doi:10.1016/j.cub.2018.06.016

Stein, T. P., Schluter, M. D., Steer, R. A., Guo, L. andMing, X. (2015). Bisphenol aexposure in children with autism spectrum disorders. Autism Res. 8, 272-283.doi:10.1002/aur.1444

Stephens, G. J., Johnson-Kerner, B., Bialek, W. and Ryu, W. S. (2008).Dimensionality and dynamics in the behavior of C. elegans.PLoSComput. Biol. 4,e1000028. doi:10.1371/journal.pcbi.1000028

Stowers, J. R., Hofbauer, M., Bastien, R., Griessner, J., Higgins, P., Farooqui,S., Fischer, R. M., Nowikovsky, K., Haubensak, W., Couzin, I. D. et al. (2017).Virtual reality for freely moving animals. Nat. Methods 14, 995-1002. doi:10.1038/nmeth.4399

Strungaru, S.-A., Plavan, G., Ciobica, A., Nicoara, M., Robea, M. A., Solcan, C.,Todirascu-Ciornea, E. and Petrovici, A. (2018). Acute exposure to gold inducesfast changes in social behavior and oxidative stress of zebrafish (Danio rerio).J. Trace Elem. Med. Biol. 50, 249-256. doi:10.1016/j.jtemb.2018.07.013

Sugathan, A., Biagioli, M., Golzio, C., Erdin, S., Blumenthal, I., Manavalan, P.,Ragavendran, A., Brand, H., Lucente, D., Miles, J. et al. (2014). CHD8regulates neurodevelopmental pathways associated with autism spectrumdisorder in neural progenitors. Proc. Natl. Acad. Sci. USA 111, E4468-E4477.doi:10.1073/pnas.1405266111

Sykes, D. J., Suriyampola, P. S. and Martins, E. P. (2018). Recent experienceimpacts social behavior in a novel context by adult zebrafish (Danio rerio). PLoSONE 13, e0204994. doi:10.1371/journal.pone.0204994

Tachikawa, K. S., Yoshihara, Y. and Kuroda, K. O. (2013). Behavioral transitionfrom attack to parenting in male mice: a crucial role of the vomeronasal system.J. Neurosci. 33, 5120-5126. doi:10.1523/JNEUROSCI.2364-12.2013

Takayanagi, Y., Yoshida, M., Takashima, A., Takanami, K., Yoshida, S.,Nishimori, K., Nishijima, I., Sakamoto, H., Yamagata, T. and Onaka, T.(2017). Activation of supraoptic oxytocin neurons by secretin facilitates socialrecognition. Biol. Psychiatry 81, 243-251. doi:10.1016/j.biopsych.2015.11.021

Tang, W., Zhang, G., Serluca, F., Li, J., Xiong, X., Coble, M., Tsai, T., Li, Z.,Molind, G., Zhu, P. and et al. (2018). Genetic architecture of collective behaviorsin zebrafish. bioRxiv. doi:10.1101/350314

Teles, M. C. andOliveira, R. F. (2016a). Androgen response to social competition ina shoaling fish. Horm. Behav. 78, 8-12. doi:10.1016/j.yhbeh.2015.10.009

Teles, M. C. and Oliveira, R. F. (2016b). Quantifying Aggressive Behaviorin Zebrafish. Methods Mol. Biol. 1451, 293-305. doi:10.1007/978-1-4939-3771-4_20

Teles, M. C., Almeida, O., Lopes, J. S. and Oliveira, R. F. (2015). Socialinteractions elicit rapid shifts in functional connectivity in the social decision-making network of zebrafish. Proc. Biol. Sci. 282, 20151099. doi:10.1098/rspb.2015.1099

Teles, M. C., Cardoso, S. D. and Oliveira, R. F. (2016a). Social plasticity relies ondifferent neuroplasticity mechanisms across the brain social decision-makingnetwork in zebrafish. Front. Behav. Neurosci. 10, 16. doi:10.3389/fnbeh.2016.00016

Teles, M. C., Gozdowska, M., Kalamarz-Kubiak, H., Kulczykowska, E. andOliveira, R. F. (2016b). Agonistic interactions elicit rapid changes in brainnonapeptide levels in zebrafish. Horm. Behav. 84, 57-63. doi:10.1016/j.yhbeh.2016.05.020

Theodoridi, A., Tsalafouta, A. and Pavlidis, M. (2017). Acute exposure tofluoxetine alters aggressive behavior of zebrafish and expression of genesinvolved in serotonergic system regulation. Front. Neurosci. 11, 223. doi:10.3389/fnins.2017.00223

Tranfaglia, M. R. (2011). The psychiatric presentation of fragile x: evolution of thediagnosis and treatment of the psychiatric comorbidities of fragile X syndrome.Dev. Neurosci. 33, 337-348. doi:10.1159/000329421

Tsuneoka, Y., Tokita, K., Yoshihara, C., Amano, T., Esposito, G., Huang, A. J.,Yu, L. M., Odaka, Y., Shinozuka, K., Mchugh, T. J. and et al. (2015). Distinctpreoptic-BST nuclei dissociate paternal and infanticidal behavior in mice. EMBOJ. 34, 2652-2670. doi:10.15252/embj.201591942

van Kerkhof, L. W. M., Damsteegt, R., Trezza, V., Voorn, P. and Vanderschuren,L. J. M. J. (2013). Functional integrity of the habenula is necessary for social playbehaviour in rats. Eur. J. Neurosci. 38, 3465-3475. doi:10.1111/ejn.12353

Varshney, G. K., Pei, W., LaFave, M. C., Idol, J., Xu, L., Gallardo, V., Carrington,B., Bishop, K., Jones, M. P., Li, M. et al. (2015). High-throughput gene targetingand phenotyping in zebrafish using CRISPR/Cas9.Genome Res. 25, 1030-1042.doi:10.1101/gr.186379.114

Vendrell-Llopis, N. and Yaksi, E. (2015). Evolutionary conserved brainstemcircuits encode category, concentration and mixtures of taste. Sci. Rep. 5, 17825.doi:10.1038/srep17825

Villacrez, M., Hellman, K., Ono, T., Sugihara, Y., Rezeli, M., Ek, F., Marko-Varga,G. and Olsson, R. (2018). Evaluation of drug exposure and metabolism in locustand zebrafish brains using mass spectrometry imaging. ACS Chem. Neurosci. 9,1994-2000. doi:10.1021/acschemneuro.7b00459

Volkova, K., Reyhanian Caspillo, N., Porseryd, T., Hallgren, S., Dinnetz, P. andPorsch-Hallstrom, I. (2015). Developmental exposure of zebrafish (Danio rerio)to 17alpha-ethinylestradiol affects non-reproductive behavior and fertility asadults, and increases anxiety in unexposed progeny. Horm. Behav. 73, 30-38.doi:10.1016/j.yhbeh.2015.05.014

von Ehrenstein, O. S., Ling, C., Cui, X., Cockburn, M., Park, A. S., Yu, F., Wu, J.and Ritz, B. (2019). Prenatal and infant exposure to ambient pesticides andautism spectrum disorder in children: population based case-control study. BMJ364, l962. doi:10.1136/bmj.l962

von Trotha, J. W., Vernier, P. and Bally-Cuif, L. (2014). Emotions and motivatedbehavior converge on an amygdala-like structure in the zebrafish.Eur. J. Neurosci. 40, 3302-3315. doi:10.1111/ejn.12692

Wang, S. H., Cheng, X. E., Qian, Z.-M., Liu, Y. andChen, Y. Q. (2016a). Automatedplanar tracking thewaving bodies of multiple zebrafish swimming in shallowwater.PLoS ONE 11, e0154714. doi:10.1371/journal.pone.0154714

Wang, X., Zheng, Y., Zhang, Y., Li, J., Zhang, H. andWang, H. (2016b). Effects ofβ-diketone antibiotic mixtures on behavior of zebrafish (Danio rerio).Chemosphere 144, 2195-2205. doi:10.1016/j.chemosphere.2015.10.120

Wang, Y., Zhong, H., Wang, C., Gao, D., Zhou, Y. and Zuo, Z. (2016c). Maternalexposure to the water soluble fraction of crude oil, lead and their mixture inducesautism-like behavioral deficits in zebrafish (Danio rerio) larvae. Ecotoxicol.Environ. Saf. 134, 23-30. doi:10.1016/j.ecoenv.2016.08.009

Wang, D., Li, Y., Feng,Q., Guo, Q., Zhou, J. and Luo,M. (2017a). Learning shapesthe aversion and reward responses of lateral habenula neurons. eLife 6, e23045.doi:10.7554/eLife.23045

Wang, S. H., Zhao, J., Liu, X., Qian, Z.-M., Liu, Y. and Chen, Y. Q. (2017b). 3Dtracking swimming fish school with learned kinematic model using LSTM network.IEEE International Conference on Acoustics Speech and Signal Processing(ICASSP).

Wang, L., Talwar, V., Osakada, T., Kuang, A., Guo, Z., Yamaguchi, T. and Lin, D.(2019). Hypothalamic control of conspecific self-defense. Cell Reports 26,1747-1758.e5. doi:10.1016/j.celrep.2019.01.078

Way, G. P., Ruhl, N., Snekser, J. L., Kiesel, A. L. and Mcrobert, S. P. (2015). Acomparison of methodologies to test aggression in zebrafish. Zebrafish 12,144-151. doi:10.1089/zeb.2014.1025

Weber, D. N. and Ghorai, J. K. (2013). Experimental design affects social behavioroutcomes in adult zebrafish developmentally exposed to lead. Zebrafish 10,294-302. doi:10.1089/zeb.2012.0780

Weber, D. N., Hoffmann, R. G., Hoke, E. S. and Tanguay, R. L. (2015). BisphenolA exposure during early development induces sex-specific changes in adultzebrafish social interactions. J. Toxicol. Environ. Health A 78, 50-66. doi:10.1080/15287394.2015.958419

Wei, Y.-C., Wang, S.-R., Jiao, Z.-L., Zhang, W., Lin, J.-K., Li, X.-Y., Li, S.-S.,Zhang, X. and Xu, X.-H. (2018). Medial preoptic area in mice is capable ofmediating sexually dimorphic behaviors regardless of gender. Nat. Commun. 9,279. doi:10.1038/s41467-017-02648-0

Weiss, L. A., Escayg, A., Kearney, J. A., Trudeau, M., Macdonald, B. T., Mori, M.,Reichert, J., Buxbaum, J. D. and Meisler, M. H. (2003). Sodium channelsSCN1a, SCN2A andSCN3A in familial autism.Mol. Psychiatry 8, 186-194. doi:10.1038/sj.mp.4001241

Whanger, P. D. (2002). Selenocompounds in plants and animals and their biologicalsignificance. J. Am. Coll. Nutr. 21, 223-232. doi:10.1080/07315724.2002.10719214

Wiltschko, A. B., Johnson, M. J., Iurilli, G., Peterson, R. E., Katon, J. M.,Pashkovski, S. L., Abraira, V. E., Adams, R. P. andDatta, S. R. (2015). MappingSub-Second Structure in Mouse Behavior. Neuron 88, 1121-1135. doi:10.1016/j.neuron.2015.11.031

Wolff, M., Casse-Perrot, C. and Dravet, C. (2006). Severe myoclonic epilepsy ofinfants (Dravet syndrome): natural history and neuropsychological findings.Epilepsia 47 Suppl. 2, 45-48. doi:10.1111/j.1528-1167.2006.00688.x

Wu, Z., Autry, A. E., Bergan, J. F., Watabe-Uchida, M. and Dulac, C. G. (2014).Galanin neurons in the medial preoptic area govern parental behaviour. Nature509, 325-330. doi:10.1038/nature13307

Wu, Y.-J., Hsu, M.-T., Ng, M.-C., Amstislavskaya, T. G., Tikhonova, M. A., Yang,Y.-L. and Lu, K.-T. (2017). Fragile X mental retardation-1 knockout zebrafishshows precocious development in social behavior. Zebrafish 14, 438-443. doi:10.1089/zeb.2017.1446

Xia, J., Niu, C. and Pei, X. (2010). Effects of chronic exposure to nonylphenol onlocomotor activity and social behavior in zebrafish (Danio rerio). J. Environ. Sci.(China) 22, 1435-1440. doi:10.1016/S1001-0742(09)60272-2

Xiao, G., Cheng, Z.-B., Huang, S.-S., Li, Y., Mao, J.-F. and Zhao, M.-R. (2015). Adelaunay triangle network based model of fish shoaling behavior for water qualitymonitor. J. Environ. Anal. Toxicol. S7, 001. doi:10.4172/2161-0525.S7-001

19

REVIEW Disease Models & Mechanisms (2019) 12, dmm039446. doi:10.1242/dmm.039446

Disea

seModels&Mechan

isms

Xie, Y. and Dorsky, R. I. (2017). Development of the hypothalamus: conservation,modification and innovation. Development 144, 1588-1599. doi:10.1242/dev.139055

Yao, S., Bergan, J., Lanjuin, A. and Dulac, C. (2017). Oxytocin signaling in themedial amygdala is required for sex discrimination of social cues. eLife 6, e31373.doi:10.7554/eLife.31373

Yokogawa, T., Hannan, M. C. and Burgess, H. A. (2012). The dorsal raphemodulates sensory responsiveness during arousal in zebrafish. J. Neurosci. 32,15205-15215. doi:10.1523/JNEUROSCI.1019-12.2012

Yu, C., Tai, F., Song, Z., Wu, R., Zhang, X. and He, F. (2011). Pubertal exposure tobisphenol A disrupts behavior in adult C57BL/6J mice. Environ. Toxicol.Pharmacol. 31, 88-99. doi:10.1016/j.etap.2010.09.009

Zabala, F., Polidoro, P., Robie, A., Branson, K., Perona, P. and Dickinson, M. H.(2012). A simple strategy for detecting moving objects during locomotion revealedby animal-robot interactions. Curr. Biol. 22, 1344-1350. doi:10.1016/j.cub.2012.05.024

Zabegalov, K. N., Kolesnikova, T. O., Khatsko, S. L., Volgin, A. D., Yakovlev,O. A., Amstislavskaya, T. G., Friend, A. J., Bao, W., Alekseeva, P. A.,Lakstygal, A. M. et al. (2019). Understanding zebrafish aggressive behavior.Behav. Processes 158, 200-210. doi:10.1016/j.beproc.2018.11.010

Zala, S. M. andMaattanen, I. (2013). Social learning of an associative foraging taskin zebrafish. Naturwissenschaften 100, 469-472. doi:10.1007/s00114-013-1017-6

Zala, S. M., Maattanen, I. and Penn, D. J. (2012). Different social-learningstrategies in wild and domesticated zebrafish, Danio rerio. Anim. Behav. 83,1519-1525. doi:10.1016/j.anbehav.2012.03.029

Zang, L., Ma, Y., Huang,W., Ling, Y., Sun, L., Wang, X., Zeng, A., Dahlgren, R. A.,Wang, C. and Wang, H. (2019). Dietary Lactobacillus plantarum ST-III alleviatesthe toxic effects of triclosan on zebrafish (Danio rerio) via gut microbiota

modulation. Fish Shellfish Immunol. 84, 1157-1169. doi:10.1016/j.fsi.2018.11.007

Zhang, B., Chen, X., Pan, R., Xu, T., Zhao, J., Huang, W., Liu, Y. and Yin, D.(2017). Effects of three different embryonic exposure modes of 2, 2′, 4, 4′-tetrabromodiphenyl ether on the path angle and social activity of zebrafish larvae.Chemosphere 169, 542-549. doi:10.1016/j.chemosphere.2016.11.098

Zhang, B., Xu, T., Huang, G., Yin, D., Zhang, Q. and Yang, X. (2018).Neurobehavioral effects of two metabolites of BDE-47 (6-OH-BDE-47 and 6-MeO-BDE-47) on zebrafish larvae. Chemosphere 200, 30-35. doi:10.1016/j.chemosphere.2018.02.064

Zhao, Y., Sun, H., Sha, X., Gu, L., Zhan, Z. and Li, W. J. (2018). A review ofautomated microinjection of zebrafish embryos. Micromachines (Basel) 10, 7.doi:10.3390/mi10010007

Zienkiewicz, A., Barton, D. A. W., Porfiri, M. and di Bernardo, M. (2015). Data-driven stochastic modelling of zebrafish locomotion. J. Math. Biol. 71, 1081-1105.doi:10.1007/s00285-014-0843-2

Zienkiewicz, A. K., Ladu, F., Barton, D. A. W., Porfiri, M. and Bernardo, M. D.(2018). Data-driven modelling of social forces and collective behaviour inzebrafish. J. Theor. Biol. 443, 39-51. doi:10.1016/j.jtbi.2018.01.011

Zimmermann, F. F., Gaspary, K. V., Leite, C. E., de Paula Cognato, G. andBonan, C. D. (2015). Embryological exposure to valproic acid induces socialinteraction deficits in zebrafish (Danio rerio): a developmental behavior analysis.Neurotoxicol. Teratol. 52, 36-41. doi:10.1016/j.ntt.2015.10.002

Zimmermann, F. F., Gaspary, K. V., Siebel, A. M. and Bonan, C. D. (2016).Oxytocin reversed MK-801-induced social interaction and aggression deficits inzebrafish. Behav. Brain Res. 311, 368-374. doi:10.1016/j.bbr.2016.05.059

Zimmermann, F. F., Gaspary, K. V., Siebel, A. M., Leite, C. E., Kist, L. W., Bogo,M. R. and Bonan, C. D. (2017). Analysis of extracellular nucleotide metabolism inadult zebrafish after embryological exposure to valproic acid. Mol. Neurobiol. 54,3542-3553. doi:10.1007/s12035-016-9917-z

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