The limbic system is a set of brain structures located in the midbrain and temporal lobes that are involved in emotion, behavior, motivation, learning, and memory. It includes structures like the hypothalamus, hippocampus, amygdala, septum, and limbic cortex. These structures work together and interact with other parts of the brain to control functions like pleasure and punishment, emotional responses, learning and memory formation. The limbic system plays an important role in regulating behaviors, emotions, and the formation of memories.

1. DR.PRIYANKA SRIVASTAVA

2.  The term Limbic means the “border”.
 Behavioral and motivational mechanisms of
the learning process & feeling of pleasure &
punishment .
 These functions of brain are mainly
performed by the basal regions of the brain
which together are called as Limbic System.

4.  In the centre- Hypothalamus
 Sub cortical structures- a)Septum
 b) Para olfactory area
 c) Ant. Nucleus of Thalamus
 d) Portions of Basal Ganglia
 e) Hippocampus
 f) Amygdala
 Limbic cortex- composed of a ring of cerebral cortex
in each side of the brain.
 Orbit frontal area, Subcallosal gyrus, Cingulate gyrus,
Parahippocampal gyrus & Uncus.

6.  The limbic cortex functions as two way
communication & association linkage between the
neocortex & the lower limbic structures.
 Hypothalamus is a major control centre for the
limbic system. It has 2 way communication pathway
with all levels of the limbic system.
 It controls most of the vegetative & endocrine
functions of the body & many aspects of emotional
behavior.

8.  Limbic structures are concerned with the
affective nature of sensory sensations whether
the sensation is pleasant or unpleasant. also
called as reward or punishment or satisfaction or
aversion.
Reward centers- major centers are along
the course of the medial forebrain bundle in the
lat. & ventro-medial nuclei of the hypothalamus.
 Lateral area on strong stimulation cause rage or
punishment where as weaker stimuli cause a
feeling of Reward.

9.  Less potent Reward centers are
 Septum
 Amygdala
 Certain areas of the thalamus &
 Basal ganglia

11.  Most potent areas for punishment are
 The central gray area surrounding the
aqueduct of Sylvius in the mesencephalon &
extending upwards into the periventricular
zones of the Hypothalamus & Thalamus.
 Less potent areas –Amygdala & Hippocampus.

12.  Rage- strong stimulation of the periventricular
zone of the hypothalamus & Lateral hypothalamus
causes animal
 1. to develop a defense posture,
 2.extend its claws
 3.lift its tail
 4.hiss
 5.spit
 6.growl
 7.develop piloerection, wide open eyes & dilated
pupils.
 Even the slightest provocation causes an
immediate savage attack.

13.  Rage phenomenon is under check by
inhibitory signals from the VM nuclei of
hypothalamus.
 In addition Hippocampi & anterior limbic
cortex i.e cingulate gyri & subcallosal gyri
suppresses rage.

14.  Exactly the opposite emotional behavior
patterns occurs when the reward centers are
stimulated.

15.  If we do something that is rewarding we keep on doing
it.
 If that is punishing we cease to do it.
 In learning & Memory- Habituation & Reinforcement.
 It is seen in animal experiments if a stimulus doesn’t
produce any response repetition of stimulus will lead
to extinction of cerebral response. ie habituation
 If the stimulus produce either reward or punishment
 The cerebral response becomes progressively more &
more reinforced & an animal builds up strong memory
traces for sensation.

16.  It is the elongated portion of the cerebral cortex
that folds inwards to form the ventral surface of
much of the inside of the lateral ventricle.
 It has numerous but mainly indirect connections
with the cerebral cortex & the basal str. Of the
limbic system.
 Any type of sensory stimulation causes activation
of at least some part of the hippocampus and it
distributes outgoing signals to the ant. Thalamus,
hypothalamus & other parts of limbic system.

18.  It can become hyper excitable & weak
stimulation can cause focal epileptic seizures.
 Role in learning- if we surgically remove B/L
hippocampi in humans basically for Tt. Of
epilepsy, then a phenomenon called as
Anterograde amnesia develops in human.
 These people are capable of short term memory
for sec. up to a minute. Converting it into long
term memory is impaired.

19.  Decision- making that are of life-or-death
importance.
 Translation of short-term memory into long-
term memory. i.e rehearse over and over
again till permanent storage takes place.
 Consolidation of long-term memories of the
verbal or symbolic thinking type is poor
without hippocampi.

20.  It is a complex of multiple small nuclei located
immediately beneath the cerebral cortex of the
medial anterior pole of each temporal lobe.
 It has abundant bidirectional connections with
the hypothalamus as well as with the limbic
system.
 It receives neuronal signals from all portions of
the limbic cortex, neocortex of the temporal,
parietal & occipital lobes especially from the
auditory & visual ass. Areas.

22.  Due to multiple connections it is called as
“WINDOW” of the limbic system.
 It sends signals back to the same cortical areas,
into the hippocampi, into the septum ,into the
thalamus & to the hypothalamus.
 Stimulation of Amygdala- Same as that of
Hypothalamus. Can give reward and pleasure.
 Other effects are- tonic movt., circling movt.,
occasionally clonic rhythmic movt., movt like
licking, chewing or swallowing.

23.  B/L ablation of Amygdala i.e. when the ant. portion
of both temporal lobes are destroyed in a monkey,
the changes in behavior is Kluver- bucy syndrome
which is demonstrated in animal as
 1) is not afraid of anything
 2)has extreme curiosity about everything
 3)forgets rapidly
 4)has a tendency to place everything in its mouth &
sometimes even tries to eat solid objects
 5)hyper sexuality that it attempts to copulate with
immature animals of the wrong sex or other species.

24.  Overall functions of amygdala seems to be
behavioral awareness areas that operate at a
semiconscious level.
 On the basis of information it make the
person’s behavioral response appropriate for
each occasion.

25.  It is most poorly understood portion of limbic
system.
 It functions as a translational zone through
which signals are transmitted from the
remainder of the brain cortex into the limbic
system & also in opposite direction.
 It functions as associated area for control of
behavior.

26. THANK YOU