10NEUROSCIENCE ■ Research Progress Summary

Laboratory Construction

After initial phase of building up the laboratory and recruitment, Professor Owen Ko has now established a team of 10 researchers and fi nished construction of all major equipment needed. With the laboratory’s emphasis on imaging, they have custom-built all their major imaging infrastructure. Main platforms the team has constructed are as follows:1. Two-photon fl uorescence excitation microscope

with integrated animal behavioral platform for in vivo imaging of neuronal network structure and activity;

2. Intrinsic signal imaging macroscope for localisation of brain regions participating in specifi c sensory processing tasks (e.g. visual processing);

3. Light-sheet fl uorescence microscope for zebrafi sh larva whole-brain imaging of neuronal structure and activity;

4. Standard biochemical equipment and culture facilities.

Research Theme 1: Neural Circuitry Mediating Sensorimotor Behaviour

The team is currently investigating neural circuits underlying sensorimotor behaviour in two model systems:

(i) Danio rerio (Zebrafi sh) larvae

Several days post-fertilisation, zebrafi sh larvae already exhibit a rich repertoire of innate behaviors, including phototaxis, optomotor and optokinetic responses, prey capture, escape responses, rheotaxis and chemosensory attraction / avoidance. As a model organism for neuroscience, larval zebrafi sh offers the distinct advantages of relatively high optical transparency and more tractable number of neurons in the brain (in the order of 105), permitting the interrogation of brain-wide activities mediating sensorimotor transformation with cellular resolution. The team is interested in fundamental questions of how neural circuits in the brain integrates sensory information originating from bilateral sensory organs to drive avoidance or escape behavior in response to signals of danger.To this end, they have constructed an integrated high-speed light-sheet microscopy and microfl uidics system, to precisely manipulate sensory environment of zebrafi sh larvae while performing volumetric whole-brain imaging of neuronal activities. They seek to characterise the brain-wide dynamics mediating chemosensory processing by larval zebrafi sh and uncover the circuit principles governing the integration of chemical signals from the bilateral nasal placodes and olfactory bulbs for the generation of appropriate avoidance responses.

Principal InvestigatorProfessor Owen Ko

TeamDanny Chan | Eva Zhao | Kuan-jung Wu | Yanyan Yang | Leo Yan | Junzhe Huang | Hei-ming Lai | Samuel Sy | Richard Li | Caroline Chen

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(ii) Mus musculus (Mouse)

To optimise survival, animals must be able to associate sensory cues with the need to perform corresponding motor responses. These processes involve coordinated neural activity and signal fl ow across primary sensory areas, association areas, and motor areas. Often, sensorimotor tasks also necessitate the acquisition of novel motor sequences from an existing motor repertoire. To understand sensorimotor learning, the team must uncover how neuronal populations across different brain regions encode various aspects of task-relevant information, such as sensory features, predicted outcomes, and the generation of complex sequences of motor commands.

In their laboratory, Professor Ko and his team have developed a platform in which animals learn to execute motor tasks in response to visual cues, while neuronal activities are recorded from different visual and motor areas by multiphoton microscopy. Combined with retrograde tracing and molecular techniques, they seek to uncover rules governing the encoding of distinct task-related and motor sequence information along pathways connecting higher visual areas to association and motor areas.

Research Theme 2: Neurovascular and Immunological Dysfunction in Neurodegenerative Diseases

(i) Neurovascular biology and dysfunction in neurodegenerative diseases

Brain function critically relies on cerebrovascular health, which depends on the integrity of two key aspects of its vasculature: the blood-brain-barrier (BBB) and neurovascular coupling. BBB prevents exposure of the brain parenchyma to potential neurotoxic substances. Neurovascular coupling ensures the instantaneous fulfi lment of heterogeneous and dynamic metabolic demands that arise from locally activated neuronal processing. Both BBB integrity and neurovascular coupling are regulated by neurovascular units (NVU), which are comprised of neurons, astrocytes and vascular mural cells including endothelial cells, vascular smooth muscle cells in the arterioles, and pericytes in the capillaries.

Schematics of in vivo behavioural and neuronal dynamics imaging platform. The animal is head- mount and performs visuomotor tasks, while simultaneous in vivo two-photon imaging can be carried out to reveal neuronal dynamics in different cortical areas including (1) rostral forelimb area (RFA, labelled by EGFP) and caudal forelimb area (CFA, labelled by tdTomato); (2) Medial agranular cortex (AGM), where the RFA and CFA projecting neurons are labelled by EGFP and tdTomato respectively; and (3) the primary visual cortex (V1) with surrounding higher visual areas (HVAs, identifi ed by intrinsic signal optical imaging). GCaMP6s labelled neurons allowed imaging of neuronal activities (regions of interest are highlighted in blue, while calcium transients of six selected neurons in V1 are shown).

Source: Professor Owen Ko

Mechanistic studies in animals modelling pathological processes affecting NVU integrity have increasingly revealed the contribution of neurovascular defects to neurodegeneration in dementia. Cerebral small vessel disease (SVD), a dominant cause of cognitive impairments in the elderly population, is a primary neurovascular disorder. On the other hand, compromised BBB and impaired neurovascular coupling are also prominent features in Alzheimer’s disease (AD). In their investigation of SVD and AD, the team employs a combination of in vivo functional imaging, in vitro structural imaging and single-cell RNA sequencing (in collaboration with Professor Dennis Lo and Professor Rossa Chiu) to study mechanisms underlying neurovascular dysfunction. They aim to reveal (1) how normal NVU integrity is maintained, and (2) mechanisms by which aging and other disease-specifi c risk factors in SVD and AD culminate in NVU dysfunction.

(ii) Neuroimmunology in the pathogenesis of Parkinson’s disease

Over the past decades, dozens of genetic loci and mutations associated with Parkinson’s disease (PD) have been identifi ed. However, the mechanisms by which such mutations cause PD remain elusive due the complexity of dynamical changes in gene regulation and protein. Neuroinfl ammation plays an important role in PD and other neurodegenerative diseases. The team is interested in the immunological linkage between the PD-associated genetic mutations (e.g. the LRRK2 G2019S mutation) and pathogenesis of PD. With support from the Margaret K. L. Cheung Research Center for Management of Parkinsonism, they employ a combination of in vitro neuronal and glial cell culture, in vivo genetic manipulation, and imaging techniques, to study the mechanisms where specifi c PD-associated mutations mediate neuroinfl ammatory responses that contribute to dopaminergic neuron loss in PD.

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■ Research and Scholarship

Member’s Full Name Details

Eva ZhaoYoung Investigator Travel Fellowship, 9th International Conference of the International Society of Vascular Behavioral and Cognitive Disorders

Member’s Full Name Details

Owen KoAbstract reviewer, 9th International Conference of the International Society of Vascular Behavioral and Cognitive Disorders

Fellowships

Journal / Conference Reviews

Name Project Title Funding Source Start Date End Date Amount (HK$)

Owen KoCharacterization and Validation of Novel MRI Amyloid Contrast Agents

Videns Incorporation Ltd 01/10/2017 31/12/2018 25,000,000

Owen KoInvestigating the Pathogenesis of Cerebral Small Vessel Disease

CUHK Faculty of Medicine – Faculty Innovation Award (Clinical Lecturer Scheme)

01/10/2017 30/09/2020 750,000

Owen Ko Scientifi c Advisor Aptorum Group Limited 2018 2018 N/A

Owen Ko Scientifi c AdvisorVidens Incorporation Limited

2018 2018 N/A

Grants and Consultancy

■ Publications

A. Journal Papers

1. Sy KHS, Ho LWC, Lau WCY, Ko H, Choi CHJ. Morphological diversity, protein adsorption, and cellular uptake of polydopamine-coated gold nanoparticles. Langmuir. 2018;34(46):14033-14045. doi:10.1021/acs.langmuir.8b02572.

2. Wang X, Li X, Zhang L, Wong SH, Wang MHT, Tse G, Dai RZW, Nakatsu G, Coker OO, Chen Z, Ko H, Chan JYK, Liu T, Cheng CHK, Cheng ASL, To KF, Plewczynski D, Sung JJY, Yu J, Gin T, Chan MT V, Wu WKK. Oncogenes expand during evolution to withstand somatic amplifi cation. Annals of Oncology. 2018;29(11):2254-2260. doi:10.1093/annonc/mdy397.

3. Zhang L, Hu W, Cho CH, Chan FK, Yu J, Fitzgerald JR, Cheung CK, Xiao ZG, Shen J, Li LF, Li MX, Wu JC, Ling TK, Chan JY, Ko H, Tse G, Ng SC, Yu S, Wang MH, Gin T, Ashktorab H, Smoot DT, Wong SH, Chan MT, Wu WK. Reduced lysosomal clearance of autophagosomes promotes survival and colonization of Helicobacter pylori. Journal of Pathology. 2018;244(4):432-444. doi:10.1002/path.5033.

B. Conference Papers

1. Zhao L, Yan LYC, Chen XY, Li ZQ, Sy SKH, Tian XY, Huang Y, Mok VCT, Ko H. Investigating the therapeutic potential of glucagon-like peptide-1 receptor (GLP-1R) agonist in cerebral small vessel disease. In: 9th International Conference of the International Society of Vascular Behavioral and Cognitive Disorders; Hong Kong; 2018 Nov 14-17.

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