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DIENCEPHALON (PART OF FOREBRAIN) ¢ Hypothalamus and thalamus are part of diencephalon ¢ These structure are composed of a group of specialized cells which connect other areas of brain. us SE Thalamus ° Greek term “ inner chamber”. It also comes from the term thalamus or bed, ° Location It lies at the most rostral end of the brain stem, in the dorsal part of the diencephalon. - Boarded medially by third ventricle Dorsally by the fornix and corpus callosum. - Laterally by the internal capsule - Thalamus in the left hemisphere and right hemisphere are connected by bridge of gray matter, called Massa intermedia. ° Structure * Thalamus is composed of a number of nuclei that interconnect with different regions of the cortex. ¢ These nuclei can be divided into three groups niniscus. obellar peduncle ema ere? atte te os res. 1. Relay Nuclei © -itis the gate way of the cortex © . carries information to and from the cortex ° - ascending sensory system projects axon to specific sensory areas of the cortex © These nuclei are also called Specific nuclei. There are four specific nuclei. A. Lateral Geniculate Nuclei (LGN) - Receives information from the retinal ganglionic cells and send to the visual cortex (v-17). 2. Specific Association Nuclei * these nuclei make complex connection with other thalamic nuclei and with other diancephalic structures, - Somealso make connection with two (Left and Right) thalamic mass, - Also project to cerebral cortex that is neither exclusively sensory nor motor areas, - Thalamus receives input from © Basal ganglia e Cerebellum e Neocortex © Medial temporal lobe ucled dian * And send back to these structures to create m=! ‘sterior involved in different functions. real terior — pom A. Pulvinar Nucleus - Located at the posterior pole of thalamus - Has reciprocal connections with i) posterior cortical areas, ii) parietal lobe areas, iii) Visual cerebral areas. B. Dorso Medial Nucleus - Receives information from other thalamic Nuclei. - Sends information to frontal association cortex. - Controls emotional behavior. D. Frontal Nucleus Receives information from mammillary body. Sends information to Limbic association cortex. Controls emotional behavior. Non- Specific Nuclei Receives input thalamic nuclei and cerebral cortex and from reticular formation of the brain stem. These non specific nuclei are thought a major role in arousing and regulating the level of activity in the wide regions of cerebral cortex. HYPOTHALAMUS ° Location ° -Located in the wall of third ventricle ° - Shaped like a funnel below thalamus ° - Represents an extension and specialization of central gray matter. ° - extended in mid brain and hind brain. ° - Hypothalamus is locatated in the principal location to integrate visceral functions. Mammillothalamic tract 4 ~ Third \ | ventricle Dorsomedial \9 bypalh alamic i ~ Fornix nucleus — ~ Lateral hypothalamic area Periventricular nucleus 4 + Supraoptic nucleus Optic tract —4 > Amygdala Ventromedial Arcuate hypothalamic nucleus nucleus Median eminence Lateral tuberal | nucleus Appleton & Lange Kandel/Schwartz/Jessell Principles of Neural Science Fig. 49.114 ° Functions - Hypothalamus is connected with i) Endocrine system \i)Autonomic nervous system ¢ Also meets with the boundary of i) Temporal lobe ii)Septal area ° tis made up of about 20 different nuclei. A.Lateral Group - This group has a number of small nuclei - These nuclei are Collectively called Lateral Hypothalamus Area ° Lecture [: The hypothalamus Overview of fapatvalatas and limbic system purpose. function and some examples of clinical conditions mediated by hypothalamic and/or limbic system neural circuitry. Brief overview of hypothalamus anatomy, Information flow into and out of the hypothalamus: inputs, outputs and pathways. Servo-control systems as a model for hypothalamic function. Two detailed examples of hypothalamic function: — Temperature regulation Hypothalamus and Limbic System: motion and Motivated Behavio ° Emotions and motivated behavior are crucial for survival: — Emotional responses modulate the autonomic nervous system to respond to threatening stimuli or situations, — Emotional responses are adaptive. If you are prepared to deal with threatening stimuli, you are more likely to survive and reproduce. - Motivated behavior underlies feeding, sexual and other behaviors integral to promoting survival and reproduction. Hypothalamus: Integrative ctions * The hypothalamus helps regulate five basic physiological needs: 1) Controls blood pressure and electrolyte (drinking and salt appetite). 2) Regulates body temperature through influence both of the autonomic nervous system and of brain circuits directing motivated behavior (e.g. behavior that seeks a warmer or cooler environment). 3) Regulates energy metabolism through influence on feeding, digestion. and metabolic rate. 4) Regulates reproduction through hormonal control of mating, pregnancy and lactation. 5) Directs responses to stress by influencing blood flow to specific tissues, and by stimulating the secretion of adrenal stress hormones. 
