BMS2-27 Hypothalamus and Lymbic System PDF

12/29/20 Hypothalamus Lymbic System and Hypothalamus 3 Assist. Prof. Dr. Cenk Serhan ÖZVEREL [email protected] Midbrain (Dienchephalon) • Homeostatic control centers • Thalamus – ‘relay station’ and sensory integration • Hypothalamus• • • • • • Hunger Thirst: Body osmolality Fight or...

12/29/20 Hypothalamus Lymbic System and Hypothalamus 3 Assist. Prof. Dr. Cenk Serhan ÖZVEREL [email protected] Midbrain (Dienchephalon) • Homeostatic control centers • Thalamus – ‘relay station’ and sensory integration • Hypothalamus• • • • • • Hunger Thirst: Body osmolality Fight or fright response Fear Control of biological rhythms Endocrine and ANS synchrony 1 12/29/20 • Paraventricular nucleus à Oxytocin + ADH • Medial preoptic Area à Bladder contraction , Heart rate, Blood pressure • Supraoptic nucleus à ADH release • Posterior preoptic and anterior hypothalamus à Body temperature, Respiration, Sweating • Lateral hypothalamus à Thirst and hunger • Arcuate nuclei à Dopamine • Periventricular Area à Neuroendocrine control • Mamillary body à Recognition memory, feeding reflexes • Ventromedial nucleus à Satiety center • Perifornical area à Hunger, Blood pressure, anger 2 12/29/20 • Dorsomedial nucleus à GIS stimulation • Posterior hypothalamus à Blood pressure, pupil dilation, Shivering • Suprachiasmic nucleus à Biological Ryhythms, Control of pineal gland 3 12/29/20 • Lateral Hypothalamus & Medial Forebrain bundle • Hunger • Thirst • Emotional drive Hypothalamus and Behaviour • Lateral Hypothalamus • Rage- Euphoria- Fight • Ventromedial nucleus • Satiety-calmness • Periventricular area • Punishment-fear • Anterior-posterior Hypothalamus • Sexual instincts Hypothalamus and Behaviour Hypothalamus and Behaviour • Punishment-Reward System • Punishment-Reward System • Reward centers • Punishment centers • Lateral hypothalamus • Ventromedial hypothalamus • Secondary areas • Septum • Amygdala • Thalamus • Basal ganglia- Basal tegmentum • Periventricular area • Lateral hypothalamus • Supressing centers: • Hippocampus • Ventromedial (VM) nucleus • Anterior limbic cortex 4 12/29/20 The Limbic System • Limbic System • Cingulate gyrus • Hippocampıs • Amygdala • Hypothalamus • Septum • Orbitofrontal cortex The Limbic System • Limbic System • Cingulate gyrus • Emotions and behaviour, decision • Hippocampıs • Learning and memory, navigation • Amygdala • Emotions and emotional memory • Hypothalamus • Septum • Orbitofrontal cortex 5 12/29/20 Limbic System • Also known as paleomammalian cortex • Brain structures located on both sides of the thalamus. • Immediately beneath medial temporal lobe of cerebrum • Primarily in the forebrain Structure • Limbic system defined by Paul D. Maclean • ‘Series of cortical structures surrounding the limit between cerebral hemispheres and brainstem’ • Limbic Lobe • Functions supported: • Emotion • Behaviour • Motivation • Long term memory • Olfaction • Limbic System Parts • Cortical Areas: • Limbic lobe • Orbitofrontal complex à decision making • Priform cortex à part of olfactory system • Entorhinal cortex à memory • Hippocampus à consolidation of new memories • Fornix àconnect hippocampus with other brain structures (Mammilary bodies and septal nuclei) 6 12/29/20 • Limbic System Parts • Limbic System Parts • Subcortical Areas: • Diencephalic Areas: • Septal nuclei à Pleasure zone • Amygdala à emotional processes • Nucleus accumbens à reward, pleasure and addiction Function • Limbic System à motivation, emotion, learning, and memory • HYPOTHALAMUS à MANY Autonomic features • Mamillary bodies à part of hypothalamus, recieves signals from hippocampus via fornix and projects them to the thalamus. • Anterior nuclei of thalamus à receive input from the mammillary bodies and involved in memory processing. • Limbic system interacts with basal ganglia • Basal ganglia à located near thalamus and hypothalamus • PLACE à subcortical structures meet the cerebral cortex • They receive input from cerebral cortex which sends outputs to the motor centers in the brain stem. • Operates via endocrine system + autonomic NS. • Striatum (Part of basal ganglia) controls posture and movement. • If Inadequate supply of dopamine, the striatum is affected à leads to visible behavioral symptoms ‘Parkinsons Disease’ 7 12/29/20 Hippocampus • Cognition processes • Spatial memory à • The first and most widely researched area concerns memory • Subregions in hippocampus à • dentate gyrus (DG) in the dorsal hippocampus, • the left hippocampus, • The dorsal hippocampus was found to be an important component for the generation of new neurons, called adult-born granules (GC), in adolescence and adulthood. • MEMORY • These new neurons contribute to pattern separation in spatial memory, increasing the firing in cell networks, and overall causing stronger memory formations. • the parahippocampal region • While the dorsal hippocampus is involved in spatial memory formation, the left hippocampus is a participant in the recall of these spatial memories. Hippocampus • Learning • New neurons and neural circuits in the hippocampus as a result of the training, causing an overall improvement in the learning of the task. • Neurogenesis 8 12/29/20 Hippocampus Damage Amygdala • Affects overall cognitive functioning, particularly memory such as spatial memory • Deepest part of the limbic system • As a result of à brain injury • involved in many cognitive processes and is largely considered the most primordial and vital part of the limbic system. • Like the hippocampus, processes in the amygdala seem to impact memory; However, it is not spatial memory as in the hippocampus but the semantic division of episodic-autobiographical memory (EAM) networks. Amygdala • Besides memory, the amygdala also seems to be an important brain region involved in attentional and emotional processes. • Social processing • evaluation of faces in social processing, is an area of cognition specific to the amygdala. 9 12/29/20 Klüver–Bucy syndrome • Based on experiments done on monkeys, the destruction of the temporal cortex almost always led to damage of the amygdala. • Major changes: 1. Monkeys were not afraid of anything. 2. The animals (monkeys) had extreme curiosity about everything. 3. The animal forgets rapidly. 4. The animal has a tendency to place everything in its mouth. 5. The animal often has a sexual drive so strong that it attempts to copulate with immature animals, animals of the wrong sex, or even animals of a different species. The End 10