Limbic System PDF

LIMBIC SYSTEM I I Limbic System r smell  LIMBIC SYSTEM The limbic system consists of group of structures that make the border between the neocortex and the brain stem. -It consists of : 1) The limbic lobe: Is the oldest part of the cortex. 2) A group of de...

LIMBIC SYSTEM I I Limbic System r smell  LIMBIC SYSTEM The limbic system consists of group of structures that make the border between the neocortex and the brain stem. -It consists of : 1) The limbic lobe: Is the oldest part of the cortex. 2) A group of deep structures intimately associated with the limbic lobe. 5 functions of limbic system  Functions Of The Limbic System 1) Reward and Punishment Function Of Limbic System: Stimulation of some brain areas is so rewarding, that the rat will ignore food to continue bar pressing and will stop when completely exhausted. Reward Centers: In the lateral and ventromedial nuclei of hypothalamus. a 2 3 Sense of reward (relaxation, pleasure and satisfaction) ewardcenter if stimulated willleadto Punishment Centers: if stimulated willleadto angry (a)A major punishment center is the periventricular nucleus of hypothalamus if stimulated willleadto fearsensation (b) Less potent centers: Amygdala and hippocampus. Importance Of Reward And Punishment Sensations: So, Reward and Punishment centers constitute one of the most important controller of body activities and behavior. Balance between Two centers In Memory And Learning Reward and punishment centers of the limbic system play an important role in selecting information that we learn. LTI Prove: Sensory experiences cause neither reward nor punishment are very hardly to be remembered or learned. Jit teas o t.ws IN may 6 to T.yWfj otwdoyiw.IihT J.w  2) Function Of Limbic System In Emotions a) Rage: at * Strong stimulation of punishment centers especially the periventricular nuclei at the hypothalamus or in the amygdala - -> rage reactions, i.e. taking attack position. * In humans: Frowning, fighting and generalized sympathetic paid stimulation (pilierection, pupillary dilatation). * In cats: Hissing, growling, elevation of the tail, pilierection and will directed biting and clawing. false S Sham Rage Reaction: si i * Means: Minor irritating stimuli —> Severe rage reactions. * Occurs after removal of neocortex in animals or lesion in tTTIaad eIÉw ventromedial hypothalamic nuclei (placidity area) cerebral a  Weakstimulationof ventromedial hypothalamicnucli eathier b) Fear: normal stimulationofamyglada Produced by stimulation of the less strong punishment areas, e.g. amygdaloid nuclei. ie Fear reactions include : Cowering, avoidance, sweating, pupillary dilatation, turning the head from side to side to seek escape. Prove: Normally the monkeys are terrified by snakes. After bilateral destruction of the amygdaloid nuclei, the monkeys approach snakes without fear, pick them up, play with them or even eat them. 2,6  Placidity: a Is opposite to rage. * Means: Quietness, calmness and mild or no response to provocation. * Produced by: a) Stimulation of placidity area: Ventromedial hypothalamic nuclei. b) Bilateral damage of amygdaloid nuclei, that is why in humans, bilateral amygdaloid lesions ----- > transform the subject from agitated and aggressive to completely placid person. A Is Balance between Two centers if one center got lesion the other will come upper hand  3) Function Of Limbic System In Motivation - Motivation is the force that activates a certain behavior to achieve a certain goal. - The main center of motivation is in the limbic association area loop 4) Function Of Limbic System In Behavior A. Feeding Behavior: is The amygdaloid nucleus is concerned with "sorting out" types 818 24 of food into edible or inedible. Lesion in amygdaloid nuclei -- ---> hyperphagia and the animal eats inedible object (Omniphagia) Do ist T.SI Wth a hñe  5) www Analysis Of Olfactory stimuli Fis i i Ii The limbic system is concerned with perception, 23531 II je discrimination and coordination of olfactoryysensation + B emotional responses to olfactory stimuli and olfactory memories especially in animals  inhibit reward andpunishment iMI a_minor major Effect of tranquilizers: Inhibit rewarding and punishment sensations Decrease in affective reactivity Neurotransmitter involved in behaviour, motivation and emotions * Noradrenaline * Dopamine Jai * Serotonin ACHI s brain S1