The limbic system, known as the 'emotional brain', is crucial for processing emotions, memory formation, and regulating behaviors essential for survival. Key components include the hippocampus, responsible for memory conversion, and the amygdala, which influences emotional perceptions and complex emotions. Dysfunction in these areas can lead to various neurological disorders, including schizophrenia and conditions related to movement such as Parkinson's disease and athetosis.

1. LIMBIC SYSTEM
• The limbic system sometimes called the ‘Emotional Brain’ because it
plays a “primary role in arrange of emotions”, including pain,
pleasure, docility, affection & anger.
• It composed of collection of brain structures involved with, mainly; The
hippocampus and amygdala (amygdaloid body), along with portions of;
 Cingulate Gyrus,
 Caudate Nuclei,
 Septum,
 Thalamus &
 Hypothalamus,
 In mammalian brain,
1. Survival of self and species.
2. Preservation of self and species.
It is the primary purpose limbic system.

2. Cont…………..!
The behavior of the mammalian brain is said to “revolve’
around”
Fighting,
Fleeing,
Mating,
Feeding,
Function of L.S.
Emotions,
Motivations,
Recall
Memory storage,
Multifaceted behavior.

3. All emotions are either: agreeable
or disagreeable.
1. The limbic system, feel pleasure
when engaged in activities that
enhance their preservation of self
& their species.
2. Pain is experienced when survival
needs are being thwarted.
 Thus, the limbic system's
perspective, all experiences are
judged in the dualistic fashion of
pleasure or pain.

4.  It interconnect with the
cerebral cortex comprises
the "human" brain and is
associated with advanced
functions such as;
1. Planning,
2. Thinking,
3. Analyzing,
4. Communicating,
5. Memory &
6. Behavior.

5.  Hippocampus
The hippocampus is comprised of rows of 40 million nerve cells. Its
main function; converting short-term memory into long-term
memory.
If damage to hippocampus, causes disability to make new
memories.
The Hippocampus in the Right hemisphere of the brain is concerned
with Visual, Emotional, Tactile, and Non-verbal memories.
The Hippocampus in the Left hemisphere stores Verbal and
Mathematical memories.
Ultimately, it stores the memories which are of emotional and
motivational significance.
Schizophrenia: The physiological aspects of schizophrenia have
been linked to the hippocampus,
The cells of the hippocampus which are normally arranged in an
ordered manner, are grossly disarranged in the brains of
“Schizophrenics” patient.

6. Amygdala
The Amygdala (amygdaloid body) is interconnected with the
hypothalamus, septal nucleus, and hippocampus.
Function: The job of the amygdala is to Discern (discard) the
emotional significance of all aspects of experience.
It adds color to thoughts and It is responsible for the capacity to
feel complex emotions, like love and anxiety.
The Amygdala is extremely sensitive to tactile stimulation and is
involved with memory.
The Visual and auditory perceptual information is received by the
amygdala causes an emotional influence on perception and
thought.
Damage to the amygdala can cause, a person to misperceive or fail
to perceive societal cues which are emotionally based.
Traditionally, the amygdala has been linked to violent tendencies
and behavior.

7. Septal Nuclei
This structure is involved with
humankind's ability to form emotional
and social bonds with one another, &
also exerts dampening effects on
mood.
Along with the hypothalamus
(emotional reservoir), it exert
emotional influence upon the rest of
the brain.
It is also interconnected with the
hippocampus, and in some ways it
serves to counteract the amygdala.
Stimulation of the septum, is known
to generate strong feelings of
pleasure.

8. Cingulate Gyrus
The cortex covering the cingulate gyrus is an important part of the
limbic system.
The cingulate gyrus involves three distinct behavior centers;
Nursing and Maternal care, and Audio-vocal communication.
The three behavior centers are exhibited by mammals which have a
cingulate gyrus, and not by reptiles who lack a cingulate gyrus.
It interfere the ‘decision-making’ processes between the frontal
cortex, the emotional functions of the limbic system, and the brain
controlling movement mechanisms.
The cingulate gyrus also communicates with the rest of the limbic
system and other regions of the frontal cortex.
Electrical stimulation of this part of the limbic system produces
feelings that are either emotionally positive or negative.
In general, the cingulate gyrus plays an excitatory role in emotions
and motivated behavior.

9. INTERNAL CAPSULE
It is v shaped band of fibers bounded medially by thalamus, caudate
nucleus & laterally by lantiform nucleus. It is divided into three limbs;
Anterior, Posterior & Genu
Most of ascending & descending cortical fibers pass through this
area, all fibers are condensed in this small area,
slight damage to this area causes; extensive loss of function on
opposite side.
Applied physiology: (Blood supply) Lateral sriate branch
(lanticulostriate artery) of the middle cerebral artery, recurrent branch
of the anterior cerebral artery & anterior choroid branch of internal
carotid artery supply the internal capsule.
One of the branches of lateral striate artery or lanticulostriate artery
is frequently ruptured & it is known as charcott’s artery of cerebral
haemorrhage.
Frequent rupture this; because of the lanticulo striate artery
remains under very high pressure & it has no collateral branches.

10. Haemorrhage due to the rupture of this artery causes apoplexy.
In apoplexy;
there is paralysis of the muscles of opposite side (hemiplegia),
loss of consciousness,
loss of control over the sphincter.

11. BASAL GANGLIA
The basal ganglia composed of;
 Carpus striatum,
 Rednucleus,
 Substantia nigra
 Body of luys
The basal ganglia plays an important part in the controlling
voluntary reflex & automatic associative movements of the
body.
Diseases of the different nuclear inclusions of the Basal Ganglia
produces disturbance in muscular activities like; Athetosis,
Parkinson (muscular rigidity,) Tremor, & Chorea etc.

12. Carpus Striatum
It is mass of gray matter, it is placed lateral & anterior to the
thalamus.
It has two part; the smaller anterior part (Caudate nuclei), the larger
posterior part (Lanticular nucleus)- 2types; putmen & globus pallidum
(pallidus).
Putmen & caudate nucleus contains small satellite cells, resembling
sensory cortex & mostly receive afferent striate fibers.
Globus pallidus contains pyramid cells or multipolar cells, all
efferent striate fibers arises from it.
Putamen & Caudate nucleus acts as receiving center, where as
globus pallidus act as discharging center of basal ganglia.
Corpus striatum communicates directly or indirectly with cerebral
cortex (areas 4, 4s, 6, 8s, & 2s), thalamus, hypothalamus, cerebellum,
midbrain.
It guides & controls the activities of almost all important parts of the
nervous system both somatic & automatic.

13. Red Nucleus:
It is a large, oval mass of the gray matter in the
tegmentum of midbrain, laying bellow the thalamus & close
to the third ventricle nucleus.
The colour of the this nucleus is due to the presence of
the reddish brown lipochrome,
It consists of;
Old-part with large cell as (nucleus magnocellularis) &
New-part with small cells (nucleus parvocellularis).
From old part, motor (efferent) fibers arises, while the
new part receives all the afferent fibers.
The kinaesthetic impulses from spinal cord, carried
through flechsig’s & gower’s tracts are relayed to the red
nucleus.

14. Substantia Nigra
It is the a mass of the nerve cells containing melanin (hence
blackish colour).
It lies between the crus-cerebri & tagmentum of the midbrain.
Functions: may be metabolic remnant of the primitive ectodermal
cells from which the nerve cells born.
Carpus luysi (body of luys): functionally, it is a part of extra-
pyramidal system.

15. Function of the Basal ganglia
It is the primitive motor cortex for voluntary muscular activity (area
4 & 6), in primates the pre-central cortex (area 4, 6) is highest motor
centers.
It control muscular activity:
It exert inhibitory effect on the spinal reflexes, & regulates the activity
of the muscles which maintain posture.
Thus diseases to Basal Ganglia produce muscular rigidity which is seen
in Parkinson’s & paralysis.
Lesion in the Globus pallidus & Substintia nigra are concerned with
the tremor in the parkinsonism.
1. Carpus striatum:
It controls automatic & associative movements:
This movements are initiated by area-6 & mediated by carpus
striatum, such as swinging of arms during walking.

16. It checks abnormal involuntary movements:
In lesion to the carpus striatum, abnormal involuntary movements
occurs.
It controls the group of movements for emotional expressions:
Disease to Carpus striatum causes lack of emotional expression
(mask like appearance: Parkinson disease)
2. Red nucleus:
It is relay station & co-ordinating center for many motor & sensory
impulses & act as a center for reflexes.
3.Substintia nigra:
it is highly developed in man & higher apes, it is regarded as the
center for the co-ordinating of those impulses which are essential
for the Skilled movements.
Substintia nigra is concerned with the tremor in the parkinsonism.

17. • Parkinson: A common, chronic degenerative disease of
the central nervous System. Its hallmarks sign include a
pill-rolling tremor of the hands, muscular rigidity, loss of
facial expression, difficulty initiating movements
(bradykinesia),
Gait disturbances (especially shuffling gait, festination, and
sometimes difficulty initiating forward movements).

18. • Athetosis: A condition in which slow, irregular,
twisting, snake like movements occur in the upper
extremities, especially in the hands and fingers.

19. • Chorea: Involuntary dancing or writhing of the
limbs or facial muscles.