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Emotion and Motivation A: Emotional states Chapter 32 Pleasure, elation, ecstasy, sadness, depression, fear, anger and calm imbue our action with passion and character Emotion, like perception and action is controlled by distinct neuronal circuits within the brain What parts of the brain are involved in emotion ? A theory of emotion must explain the relationship of cognitive and physiological states How is the emotion represented in the cortex ? How do subcortical structures regulate the autonomic and endocrine systems ? Hypothalamus communicates reciprocally with areas of the cerebral cortex, information about the conscious and peripheral aspects of emotion affect each other The hypothalamus is a critical subcortical structure in the regulation of emotion - homeostatic mechanism Hypothalamus regulates the vital functions that vary with emotional states : temperature, heart rate, blood pressure, and water and food intake (autonomic system). Hypothalamus also controls the endocrine system. The autonomic nervous system participates in emotional states - Sympathetic: fight or flight - parasympathetic: rest and digest - enteric The autonomic nervous system is controlled by many region of the brain, the cerebral cortex, the amygdale that influence the autonomic system through the hypothalamus. Visceral afferents Hypothalamic nuclei Hormonal output Nucleus Of the Solitary tract Target organs Autonomic output Brain stem nuclei Autonomic Preganglionic nuclei The hypothalamus controls the endocrine system - directly by secretion of neuroendocrine products in to the general circulation from the pituitary - indirectly by secretion of regulating hormones in to the pituitary Manifestations of emotional states can be selectively elicited by stimulating the hypothalamus hypothalamus is the coordinating center that integrates various inputs into a well organized set of autonomic and somatic responses The search for cortical and subcrotical representation of emotions has led to the amygdala The amygdala is the part of limbic system most specifically concerned with emotion The amygdala mediates both inborn and acquired emotional responses Emotional memories are not stored in the amygdala directly but are stored in the cingulate and parahippocampal cortices, with which the amygdala is interconnected B: Motivation Chapter 33 Motivation is the area of biology concerned with internal needs rather than with the processing of sensory information Motivational state is thought to be controlled by homeostatic process Motivation varies as a function of deprivation Motivational states serve three functions 1- Directing function 2- Activating function 3- Organizing function Attainment of a goal decreases the intensity of the motivational states Curiosity and sexual arousal do not appear to be based on any well-defined physiological deprivation Motivation intensity and direction of behaviors Homeostatic mechanisms - Hypothalamus Internal environment of the body is highly regulated so as to be maintained in a stable, narrow range. This constancy is the result of homeostatic mechanisms that limit the variability of body state Homeostatic processes such as temperature regulation, feeding and thirst correspond to motivational states Homeostatic mechanisms can be understood by analogy with the control system or servo mechanisms Chemical stimulation of the hypothalamus alter feeding behavior Each type of nutrient is regulated with different neurotransmitters - norepinephrine - peptide galanin - opiates carbohydrates fat protein Temperature regulation involves integration of autonomic, endocrine and skelomotor responses Hypothalamus regulates body temperature Anterior hypothalamus Posterior hypothalamus heat dissipation heat conservation Normal body temperature is the set point In addition to driving appropriate autonomic, endocrine and nonvoluntary skeletal responses, the error signal of can also drive voluntary behaviors warm-sensitive neurons cold -sensitive neurons Feeding behavior is regulated by short-term and long-term cues Short-term cues regulate the size of individual meals and long term cues regulate the overall body weight The effectiveness of short-term cues is modulated by some longterm signal reflecting body weight (related to total fat stores) Feeding behavior is regulated by a great variety of mechanisms body weight is regulated around a set point body must provide feedback signals that control nutrient intake and metabolism Although body weight various from animal to animal , the daily expenditure of energy is constant across and within species Dual controlling elements are involved in the control of food intake Lateral hypothalamus Medial hypothalamus feeding center satiety center Hypothalamic lesions alter the feeding behavior 1- Alteration of sensory information 2- Alteration of set point 3- Alteration of hormonal balance 4- Effect on fibers of passage Thirst is regulated by tissue osmolality and vascular volume The hypothalamus regulates water balance by direct physiological action It also regulates the behavioral aspects of drinking A set point of water intake appears to exist Drinking is controlled by : Tissue osmolality : osmoreceptors (or sodium-level receptors, probably neurons) can respond to the osmatic pressure of the extracellular fluid Change in vascular volume : are detected in the low pressure side of the circulation Dryness of the tongue and high body temperature : detected by thermosensitive neurons Motivational states can be regulated by factors other than tissue needs Curiosity and sexual responses do not appear to be controlled by the lack of specific substances in the body Homeostatic responses are modulated by innate and learned mechanisms - Ecological constraints may shape motivated behaviors - Behavior may anticipate physiological deficits - Pleasure is an important but poorly understood factor in motivating behavior - Intracranial stimulation cam simulate motivational states and reinforce behavior Only once have I been made mute. It was when a man asked me, ‘Who are you ?’ Gibran Kahlil Gibran