PHYSIOLOGY DEPARTMENT CENTRAL NERVOUS SYSTEM PHYSIOLOGY. LECTURE #2. PHYSIOLOGY OF ‘DIENCEPHALON’ CEREBELLUM PHYSIOLOGY Ass. Prof. VASTYANOV Rooslan ATTENTION !!! DIENCEPHALON Diencephalon is the part of the forebrain that locates more rostral compared with the brain cortex and subcortical nuclei. The 'diencephalon' includes the hypothalamus, thalamus and subthalamus. Thalamus and the reticular formation Motor (frontal) cortex Sensoric cortex To the limbic system Thalamus Hypothalamus Amygdala Reticular formation Tractus Spinothalamicus Ganglion spinalis Spinal cord Sensor fiber Pain receptor The main thalamic nuclei Specific nuclei Relying Associative Motor Nonspecific nuclei Specific thalamic nuclei Relying Associative Motor Ventrobasal Mediodorsal N.N. frontolateral complex nucleus and ventrolateral Tactile, Projections to proprioceptive, frontal lobes Putamen Signals rely temperature, from cerebellum pain, gustatory Projections to tempo- and basal inputs to brain ral and occipital lobes gangles to motor somatosensory Nucleus lateralis cortex cortex dorsalis Projections to N.geniculatum int. temporal lobe Nucleus frontalis Audial information in- to brain audial centers Projection to limbic cortex N.geniculatum ext. Visual information in- to brain visual centers Thalamus rely function All sensory pathways have direct projections to thalamic nuclei, which convey the information to restricted areas of the sensory cortex. Coordination and integration of peripheral sensory stimuli occur in the thalamus «… thalamus serves as the rely station, where all the external stimuli, coming together, change their expression and go to subcortical and cortical centers». А. К. Walker HYPOTHALAMUS and its main nuclei FUNCTIONS of hypothalamus N1 1. Water and electrolyte balance regulation (supraoptic and paraventricular nuclei). 2. Secretion of hypothalamic releasing factors (arcuate and periventricular nuclei and parvocellular cells of the paraventricular nucleus). 3. Temperature regulation (the anterior and posterior hypothalamic nuclei). 4. Activation of the sympathetic nervous system and adrenal medullary hormone secretion (the dorsal and posterior hypothalamus). FUNCTIONS of hypothalamus N2 5. Thirst and drinking regulation (lateral hypothalamus). 6. Hunger, satiety and the regulation of eating behavior (the arcuate nucleus, ventromedial nucleus, and lateral hypothalamic area). 7. Regulation of sexual behavior (the anterior and preoptic hypothalamic areas). 8. Regulation of circadian rhythms. Sleep-wakefullness cycle (the suprachiasmatic nucleus of hypothalamus). Experiment with hypothalamus self-irritation (Olds) Circadian Rhythms Regulation FUNCTIONS of hypothalamus N3 9. Aggressive behaviour regulation (the anterior hypothalamic area). Hypothalamus is the important integrative center of vegetative, somatic and endocrinal functions, that is responsible for the complex homeostatic reactions realization and serves as the key structure within the hierarchically organized brain system that regulates visceral functions. CEREBELLUM The cerebellum ("small or diminutive brain") consists of two cerebellar hemispheres joined by a vermis. Cerebellar cortex, only a few mm thick, lies in the surface. Deep to the cortex lies the white matter. Within the white matter, masses of gray matter, called cerebellar nuclei, are found. Mossy fibers (spino-, reticulo-, vestibulo- and corticocerebellar) Cerebellar make complex multicontact inputs synapses jn granule cells. (afferent) Climbing fibers arise from the infe- rior olive, a nucleus in the medulla. Each climbing fiber synapses directly on the dendrites of a Purkinje cell and exerts a strong excitatory influence. Adrenergic fibers arise from the locus coeruleus, a basal ganglia structure. These fibers are considered to perform the trophic function. The layers of cerebellar cortex Types of the cerebellar cortical cells Basket cells their projections terminate on the Purkinje cells bodies Stellate cells their projections terminate on the Purkinje cells dendrites Purkinje cels their dendrites reach upward into the molecular layer their axons go downward and make synapses with cerebellar nuclei some axons terminate on vestibular nuclei Golgi cells their dendrites reach upward into the molecular layer, their axons go the the granular cells Granular cells their axons reach upward into the molecular layer and make synapses with Purkinje, basket and stellate cells Purkinje cells constantly generate IPSP This is critically important for the cerebellar nuclei activity inhibition because they are constantly generate tonic activity Purkinje cells excitation through Both stellate cells and basket climbing and mossy fibers results in cells – induced Purkinje cells IPSP generation increasing that lead activity inhibition results in their in turn more expressed cerebellar activation that lead to cerebellar nuclei activity inhibition. nuclei activity increasing. TOPOGRAPHIC CLASSIFICATION OF CEREBELAR CORTEX AND NUCLEI 1. MEDIAL zone – has projections on the fastigial n. 2. INTERMEDIATE zone – has projections on the interposed n. 3. LATERAL zone – has projections on the dentate n. Functions of cerebellum 1. Posture and muscular tone regulation 2. Slow aimed movements correction and their coordination with the postural reflexes 3. Sensorimotor coordination of quick aimed movements performed from the commands out of brain cortex. 1. MEDIAL zone – n. gastigial – medulla oblongata, vestibular nuclei 2 INTERMEDIATE zone – interposed n. – red n. + brain cortex. 3 LATERAL zone – dentate n. – thalamus – brain cortex motor zone Cerebellar lesions THANKS FOR ATTENTION !
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