Limbic system
Limbic system
 Means ‘border’
 Includes cortical and subcortical structures in the forebrain
 Seat of emotions and feelings
Emotions and feelings
 Emotional state
 physical sensation
 conscious feeling
 Different regions of brain involved in physical and mental
component of emotional state
Physiology of Emotions
 Aroused state have intense feeling, autonomic activation and
related behavior
Components
 Mental
 Physical
Mental or sensory component
 Cognition – aware and
recognize the sound
 Affect – development of
feeling (frightening)
 Conation – force which
direct to take action (plan
to runaway)
Physical component
 Somatic – changes in skeletal muscle (running away)
 Autonomic – sympathetic and parasympathetic (
RR)
HR, BP,
Neural system that control emotions
Limbic system
Limbic cortex
Ring of phylogenetically
primitive cortex (paleocortex)
 Cingulate gyrus – medial
aspect of the cerebral
hemisphere
 Parahippocampal gyrus
and uncus - ventromedial
surface of the temporal lobe
 Orbitofrontal area on the
ventral surface of the frontal
lobes
 Subcallosal gyrus
Subcortical limbic areas
 Amygdala.
 Hypothalamus
 Septum
 Paraolfactory area
 Anterior nucleus of the
thalamus
 Portions of the basal ganglia
 Hippocampus
Papez circuit
 Hypothalamus
communicates reciprocally
with areas of the limbic
cortex
 Conscious and the
autonomic components of
emotion influence each
other
Cingulate
gyrus
Anterior
nucleus of
thalamus
Hippocampus
Mammillary
body of
hypothalamus
Papez circuit
 Hippocampal formation
processes information from
the cingulate gyrus
 Conveys it to the mammillary
bodies of the hypothalamus by
way of the fornix
 Hypothalamus provides
information to the cingulate
gyrus
 by a pathway from the
mammillary bodies to the
anterior thalamic nuclei (the
mammillothalamic tract)
 From there to the cingulate
gyrus
Functions of limbic lobe
 Motivation
 Addiction
 Emotions of rage, fear, anxiety, aggression
 Sexual behavior
 Autonomic responses
Motivation
 Act that moves the will
Reward or punishment
 affective nature of sensations
- whether the sensations
are pleasant or unpleasant.
 Reward and punishment
centers in brain identified
by experimental studies
Skinner box
Reward centers
 Nucleus accumbens
 Along the medial forebrain bundle – which extends from the
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septal and orbitofrontal cortex to brain stem
Ventromedial and lateral nucleus of hypothalamus
Septum
amygdala
certain areas of the thalamus and basal ganglia
Punishment centers
 Central gray area surrounding the aqueduct of Sylvius in the
mesencephalon
 Periventricular zones of the hypothalamus and thalamus
Addiction
 Compulsion to repeatedly use a substance inspite of knowing
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negative impact of the substance to health
Mechanism – increase in dopamine concentration in reward
system
Areas:
Nucleus accumbens
Projections from frontal cortex, amygdala, hippocampus
Rage and placidity
 Rage – anger when person loses temper to minor
stimuli
Neocortex
Ventromedian hypothalamus
septum
Amygdala
 Placidity – person not disturbed even to major
irritating stimuli
 Bilateral lesion of amygdala
Aggression
 Violent form of rage
 Hypothalamus
 Amygdala
Fear
 Hypothalamus
 Amygdala
Sexual behavior
 Basic sexual drive is a function of limbic system and
hypothalamus and cortex
 Controlled by neural and endocrinal factors
Anxiety
 Uncertainty about future or apprehension of unknown
 Frontal part of temporal lobes
 Benzodiazipines (Anxiolytics)– act by cl- conductance in
receptors
Autonomic responses to emotions
 Amygdala
 Hypothalamus
 Emotions affect
 Cardiovascular system
 Respiratory system
 GIT
Regulation of feeding behavior
 Hypothalamus
 Satiety center – ventromedian nucleus
 Lateral hypothalamus – feeding center
 Amygdala – movement with eating (chewing, swallowing,
licking)
Hypothalamus
 Responsible for the physiological effects of emotions
 Electrical stimulation in cats of the lateral hypothalamus
cause autonomic and somatic responses characteristic of
anger
 increased blood pressure
 raising of the body hair
 pupillary constriction
 arching of the back
 raising of the tail.
 (Defensive)
Behavioral functions of the
hypothalamus
 Lateral nucleus – appetite and thirst, rage
 Ventromedial nucleus – satiety, tranquility
 Periventricular area – fear
 Sexual drive – most anterior and posterior regions
Lesions of the hypothalamus
 Lesions of lateral nucleus –decreased eating and drinking,
passivity
 Lesions of ventromedial nucleus – excessive drinking and
eating, hyperactivity
Amygdala
 Multiple small nuclei located beneath the cerebral cortex of
medial anterior pole of each temporal lobe.
 Has bidirectional connections with the hypothalamus and
other areas of the limbic system.
 Basolateral nuclei – receives afferent information
 Central nucleus – efferent connections with hypothalamus
and brain stem areas
Functions of amygdala
 Electrical stimulation of the amygdala in humans produces
feelings of fear and apprehension.
 Mediates both inborn and acquired emotional responses
 Responsible for fear conditioning
 Has a role in the conscious feeling and autonomic
manifestations of emotional state
Conditioning of fear
 Hypothalamus – responsible for the somatic expression of
emotion
 Cingulate gyrus and parahippocampal gyrus – conscious
feeling
Role of the cortex
 Cingulate gyrus and the prefrontal cortex
– conscious experience of the emotion
 Lesions of the cingulate gyrus or the prefrontal
cortex –
 Pain is perceived and autonomic responses are
present
 Unpleasant experience is absent
KluverBucy syndrome
 When the anterior parts of both temporal lobes are
destroyed in a monkey
 Characteristics of the animal
 not afraid of anything
 has extreme curiosity about everything
 forgets rapidly
 has a tendency to place everything in its mouth and sometimes
even tries to eat solid objects
 Strong sex drive
Neurotransmitters
 Dopaminergic system (Nucleus accumbens) – motivation and
addiction
 Serotonergic system – mood elevator, suppress sleep
 Histaminergic system – arousal, sexual behavior, regulation
of BP, water intake
 Cholinergic system – learning, memory, cognition, sleep