Limbic System Final
Transcript of 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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