Limbic System Final

8/7/2019 Limbic System Final

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LIMBIC SYSTEM

- SAMANTHA CARNEIRO


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The limbic system consists of the limbic

lobe and other subcortical structures andtheir connections. Although not

empirically proven, the limbic system is

a functional concept which may be

employed to explain various brain

functions.


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COMPONENTS OF THE LIMBIC SYSTEMCOMPONENTS OF THE LIMBIC SYSTEM

The brain regions that constitute the limbic system are:

Limbic cortex

Cingulate gyrus

Parahippocampal gyrus

Hippocampal formation

The dentate gyrusHippocampus

Subicular Complex

Amygdala

Septal areaHypothalamus

These structures form a complex network for

controlling emotion.


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Circuits ofCircuits of amygdalaamygdalaAmygdala serves to integrate information

processing between prefrontal / temporal

association cortices and the hypothalamus.

The amygdala has two major output pathways:

Dorsal route and Ventral routeBasolateral circuit

This circuit encodes information about social

signals and social plans for social acts. The circuithas been proposed as a substrate for the human

ability to infer the intentions of others from their

language, gaze and gestures


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Amygdala Connections

Cerebral cortex

Thalamus

Brainstem reticular formation

Hypothalamus

AMYGDALA


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Limbic System and Basal NucleiLimbic System and Basal Nuclei

Temporal lobe

Hippocampus

Amygdala

Ventral Striatum

Caudate Nucleus

Anterior Cingulate Gyrus

Globus Pallidus

Substantia nigra


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FUNCTIONSOFTHE LIMBIC SYSTEM

Olfaction

The limbic structures are closely related to theolfactory cortex and have a role in the processing

of olfactory sensation. Amygdala is involved in

the emotional response to smell

Appetite and eating behaviours:

Amygdala plays a role in food choice. The lateral

nucleus of the hypothalamus is the centre for

control of feeding whereas the ventromedial

nucleus functions as the satiety centre


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Sleep and dreams:

The limbic system is one of the most active brain

areas during the process of dreaming. Thesuprachiasmatic nucleus of hypothalamus is the

circadian rhythm generator

Emotional responsesFear:

Fear responses are produced by the stimulation of

the hypothalamus and amygdala. Amygdalardestruction abolishes fear and its autonomic and

endocrine responses. Amygdala is also involved in

fear learning


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Autonomic and endocrine responses to

emotion: Limbic stimulation causes changes in

respiration and blood pressure. The stimulation ofthe cingulate gyrus and hypothalamus can elicit

autonomic responses. The massive sympathetic

discharge during stress is called the flight or frightresponse.

SexualSexual behaviorbehavior::

The medial preoptic area of the hypothalamus is

a key structure in the central control of male

sexual behavior.


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Addiction and motivationAddiction and motivation

The reward circuitry underlying addictive behavio

includes amygdala and nucleus. This pathway isinvolved in the motivation to take drugs of abuse

and the compulsive nature of drug-taking

MemoryMemory

Emotional memory: Emotion has powerful

influence on learning and memory. Amygdala, in

conjunction with prefrontal cortex and medial

temporal lobe, is involved in consolidation and

retrieval of emotional memories. Hippocampus is

critical for long-term memory storage.


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Diencephalic memory system:The diencephalic

memory circuit consists of the hypothalamus,

mammillary body and the dorsomedial nucleus of

thalamus. This circuit is important for the storage

of recent memory

Social cognition:Social cognition:

Social cognition refers to thought processes

involved in understanding and dealing with otherpeople. Limbic structures involved are the

cingulate gyrus and amygdala.


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CLINICAL IMPLICATIONSEpilepsy

Temporal lobe epilepsy most often caused by

hippocampal sclerosis.

Limbic encephalitisLimbic encephalitis is a paraneoplastic syndrome

that has been reported with carcinoma of the lung,

breast and some other primaries. Afflicted patientsdevelop subacute onset of memory loss, dementia,

involuntary movements and ataxia.


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DementiaDementia

Degenerative changes in the limbic system have a

role in neurodegenerative diseases, particularlyAlzheimer's

Anxiety disordersAnxiety disordersAnxiety disorders may be the result of a failure of

the anterior cingulate and hippocampus to

modulate the activity of the amygdala

SchizophreniaSchizophrenia

There is reduced limbic volumes in schizophrenia.


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Affective disordersAffective disorders

The dysfunction of this system especially the

anterior limbic network is suggested in bipolardisorder

AutismAutismAutism and Asperger's syndrome involve the

disproportionate impairment in specific aspects of

social cognition.L

imbic structures involvedinclude the cingulate gyrus and amygdala


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ADHDADHD

Limbic structures have been implicated in the

genesis of ADHD. Enlarged hippocampus andDisrupted connections between the amygdala and

orbitofrontal cortex is seen in children and

adolescents with ADHD

Korsakoff's psychosisKorsakoff's psychosis

Korsakoff's psychosis is caused by damage to

mammillary bodies, dorsomedial nucleus of

thalamus and hypothalamus. It is a syndrome

associated with chronic prominent impairment of

recent and remote memory


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Documents

Limbic System Final