Dr. Vohra1. 2 Emotional Nervous System 3 The main object of primitive life are FOOD & SEX. Food is necessary for survival of individual & sex for the.

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Emotional Nervous System

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The main object of primitive life are FOOD & SEX. Food is necessary for survival of individual & sex for the survival of the species. The brain is therefore adapted to control & regulate behavior of the animal through a system called the Limbic System. It is a set of evolutionarily primitive brain structures located on top of the brainstem & buried under the cortex, are involved in many of our emotions & motivations, particularly those that are related to survival. Such emotions include fear, anger, & emotions related to sexual

behavior .

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The limbic system earns its name from its position on the medial rim of the brain.

Limbic system consists of a number of structures with complex connections which all ultimately

project into the hypothalamus. 

It appears to be primarily responsible for our emotional life, formation of memories & internal

homeostasis   .

Controls Emotions Emotional Responses Hormonal Secretions Mood Motivation Pain & Pleasure Sensations

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The limbic system includes the hypothalamus, the hippocampus, amygdala, Septum and several other nearby

areas  .

Principal parts of the limbic system & their relationship with the hypothalamus

Cingulate gyrus

Hippocampal formation

Amygdala

Hypothalamus

Ventral amygdafugal

pathwayStria

terminalis Medial forebrain bundleFornix

Septum

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The powerful input to the limbic system from the neocortex association areas links complex ‘goal directed’ behavior to more primitive instinctual behavior & internal homeostasis in a cascade of neuronal connections. Reception of information from outside world through (e.g. vision, hearing & touch) are refined in the parietal-occipital association areas. This information then conveyed to the frontal association areas involved in planned behavior (regulation) & also to the temporal association areas, where information can reach supramodal status & meaning (sementic processing)

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Entry of the information into the limbic system is either directly, to the amygdala, or indirectly to the hippocampal formation, via entorhinal area. The amygdala appears to provide suggestion to experience & especially relevant to social stimuli. The affect is an evolutionary development from more primitive ‘feelings’, derived from sensory autonomic input bodily

organs into the hypothalamus .

The information permits a link to previous experience since the hippocampal formation is essential to remembering & learning (memory)

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a coronal view

Circadian rhythms

are regular changes in mental and physical characteristics that occur in the course of a day

Hypothalamus is the most ventral part of the diencephalon lying beneath the thalmus .

Its functions include homeostasis, emotion, thirst, hunger, circadian rhythms, and control of the autonomic nervous system. In addition, it controls the pituitary

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Amygdala- lies near the temporal pole, b/w the inferior horn of lateral ventricle & lentiform nucleus. It receives afferents from inferior temporal association cortex the septum & olfactory tract .

The principal efferent projection from amygdala is stria terminalis which runs in the wall of the lateral ventricle terminate in the hypothalamus. The ventral amygdofugal path also projects to the hypothalamus .

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Connects with the hippocampus, the septum, the prefrontal area and the thalamus. These connections make it possible for the amygdala to play its important role on the mediation and control of major affective activities like friendship, love and affection, on the expression of mood and, mainly, on fear, anger and violent behavior. The amygdala, being the center for identification

of danger .

When triggered, it gives rise to fear and anxiety which lead the person into a stage of alertness, getting ready to flight or fight. Damage or destruction of both amygdalas (there are two of them, one in each hemisphere) makes the

individual, sexually non-discriminative, and unconcerned to danger .

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The septum or septal region lies beneath the rostral part of the corpus callosum. Interconnects with the amygdala & projects to the hypothalamus via medial forebrain bundle .

Cingulate gyrus

Hippocampal formation Amagdala

Septum

Hypothalamus

Ventral amygdafugal

pathway

FornixStria

terminalis

Medial forebrain bundle

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The total act of copulation is organized in the anterior part of the hypothalamus and the neighboring septal region. In the male, erection of the penis and ejaculation are organized in this area, which is adjacent to the area for urination. Under normal circumstances the neurons that organize mating behavior do so only when they receive relevant hormones in their blood supply. But when the septal region is electrically stimulated in conscious patients, sexual emotions and thoughts are produced.

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Dr. Vohra16The interconnection of limbic structures which constitute the Papez circuit

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The cingulate gyrus & parahyppocampal gyrus are in continuity with one another around the splenium of the carpus callosum. It provides a pathway from the thalamus to the hippocampus, seems to be responsible for focusing attention on emotionally significant events, and for associating memories to smells and to pain .

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Korsakoff’s psychosis is a condition that mainly affects chronic alcoholics. It is due vitamin B deficiency leads to capilary haemorrhages in the upper brain & limbic system. The syndrome is characterized by a severe memory defect, especially for recent event. Psychologists working with these patients often have great problems sorting out what is truth and what is lies of what patients say .

Temporal lobe or complex partial seizers arising close to the amygdala & hippocampi can lead to complex experience of smell, mood & memory .

Other symptoms may include hallucination, anxiety, fear, depression, confusion, delusions and insomnia; painful extremities, sometimes bilateral wrist drop, more frequent bilateral foot drop with pain or pressure over the long nerves .

Surgical ablation of amygdala has removed the uncontrollable anger reactions in some psychotic patients

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