The limbic system Neuronal circuitry controls of emotional behavior and motivational drives Neuronal circuitry controls of emotional behavior and motivational drives Composed of subcortical and cortical components Composed of subcortical and cortical components

Limbic System Figure 12.18

limbic

Subcortical group Hypothalamus,septum,paraolfactory area,epithalamus,ant.thalamic nuclei,hippocampus,amygdala,basal gangeli

Limbic cortex Orbitofrontal coretx,subcallosal gyrous cingulate gyrus and parahippocamp gyrous Orbitofrontal coretx,subcallosal gyrous cingulate gyrus and parahippocamp gyrous

Limbic System: Emotion and Cognition The limbic system interacts with the prefrontal lobes, therefore: The limbic system interacts with the prefrontal lobes, therefore: One can react emotionally to conscious understandings One can react emotionally to conscious understandings One is consciously aware of emotion in one’s life One is consciously aware of emotion in one’s life Hippocampal structures – convert new information into long-term memories Hippocampal structures – convert new information into long-term memories

The hypothalamus not only influences how you feel, it influences how you interpret the consequences of those feelings.

limbic

Visceral Afferents Nucleus of the Solitary Tract Brain Stem Nuclei Autonomic Preganglionic Nuclei Hormonal Output Autonomic Output Target Organs Hypothalamic Nuclei Hypothalamic Role in Emotion

Hypothalamus Pituitary Releasing Factors Autonomic Nervous System Adenohypophysis (Anterior Pituitary) Neurohypophysis (Posterior Pituitary) Sympathetic Parasympathetic

“I feel fear!”

Hypothalamus Amygdala Cortex, septum medial forebrain bundle Amygdala ventral route Brainstem spinal cord medial forebrain bundle stria terminalis Anterior Nucleus mtt Brainstem dorsal long. fasciculus post. magno (SO, PV) ant. parvo Pituitary

Hypothalamus,Major Hypothalamus is the most important output sorce Hypothalamus is the most important output sorce It communicate with brain stem by medial forebrain bundle,bidirectionaly between forebrain and brain stem It communicate with brain stem by medial forebrain bundle,bidirectionaly between forebrain and brain stem

Hypothalamus cont. Controls: 1-vegetative and endocrine functions 2-behavior and motivation Controls: 1-vegetative and endocrine functions 2-behavior and motivation

vegetative and endocrine functions Cardiovascular regulation involves 1-Post. And lateral hypothalamus area, increase BP and HR. 2-preoptic area,decrease BP and HR *1and 2 mediated by cardiovascular centre in the pontile and medullary part of reticular formation Cardiovascular regulation involves 1-Post. And lateral hypothalamus area, increase BP and HR. 2-preoptic area,decrease BP and HR *1and 2 mediated by cardiovascular centre in the pontile and medullary part of reticular formation

Body temperature regulation Preoptic area Preoptic area

Thermo-regulation (body temperature) Involves autonomic nervous, endocrine, and skeletomotor systems Involves autonomic nervous, endocrine, and skeletomotor systems Body temperature detectors Body temperature detectors Peripheral: skin, spinal cord, viscera Peripheral: skin, spinal cord, viscera Central: anterior hypothalamus Central: anterior hypothalamus Body temperature effectors Body temperature effectors Heat retention or generation: posterior hypothalamus Heat retention or generation: posterior hypothalamus Heat dissipation: anterior hypothalamus Heat dissipation: anterior hypothalamus

Thermo-regulation (body temperature) Heat dissipating mechanisms Heat dissipating mechanisms Dilation of blood vessels in the skin Dilation of blood vessels in the skin Inhibition of shivering Inhibition of shivering Heat conserving mechanisms Heat conserving mechanisms Vasoconstriction of blood vessels in the skin Vasoconstriction of blood vessels in the skin Shivering Shivering Increased secretion of thyroxin Increased secretion of thyroxin

Methods of thermo-regulation by the body Response to ColdResponse to Heat

Regulation of body water intake Thirst centre,lateral hypothalamus Thirst centre,lateral hypothalamus Electrolyte concentrationmaking desire to drink Electrolyte concentrationmaking desire to drink Supraopticx:urinary excrition due to ADH Supraopticx:urinary excrition due to ADH

Thirst Function of serum osmolality and blood volume Function of serum osmolality and blood volume Osmotic receptors in the hypothalamus Osmotic receptors in the hypothalamus Volume receptors in the right atrium of the heart and great veins Volume receptors in the right atrium of the heart and great veins Vasopressin release from hypothalamus Vasopressin release from hypothalamus Increases water reabsorption from the kidney Increases water reabsorption from the kidney Inhibited by ethanol Inhibited by ethanol

Circadian Rhythm Oscillations during the course of the day Oscillations during the course of the day Corticosteriods Corticosteriods Feeding and drinking behavior Feeding and drinking behavior Growth hormone secretion Growth hormone secretion Lesions of the suprachiasmatic nuclei of the hypothalamus disrupts these oscillations Lesions of the suprachiasmatic nuclei of the hypothalamus disrupts these oscillations

Control of Feeding

Feeding Complex interaction of many systems Complex interaction of many systems Regulation of energy metabolism by the Ventromedial and Lateral nuclei of the hypothalamus Regulation of energy metabolism by the Ventromedial and Lateral nuclei of the hypothalamus Physical Lesions produce hyperphagia and obesity or reduced attention to food. Physical Lesions produce hyperphagia and obesity or reduced attention to food. Amygdala may also be involved indirectly Amygdala may also be involved indirectly Lesions produce hyperphagia-like symptoms Lesions produce hyperphagia-like symptoms Ventromedial hypothalamic lesions also cause increased insulin secretion Obesity. Ventromedial hypothalamic lesions also cause increased insulin secretion Obesity.

Feedback Mechanisms Controlling Feeding Feedback from gut hormones Feedback from gut hormones e.g. Cholecystokinin e.g. Cholecystokinin Released from small intestine in response to feeding Released from small intestine in response to feeding Inhibits or suppresses feeding Inhibits or suppresses feeding

Uterine contraction and milk ejection Oxytocin stimulation by PARAVENTRICULAR Oxytocin stimulation by PARAVENTRICULAR

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مسيرهاي پردازش اطلاعات

Hippocampus circuit Ent. cortex From perforant To dentate gyrous mossy fiber cA3 schaffer collaterals cA1 to subiculum to ento cortex Ent. cortex From perforant To dentate gyrous mossy fiber cA3 schaffer collaterals cA1 to subiculum to ento cortex