Slide 1 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Bear: Neuroscience: Exploring the Brain 3e Chapter 16: Motivation

Slide 2 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins The Hypothalamus, Homeostasis, And Motivated Behavior Three components of neuronal response (periventricular zone) Humoral response --> pituitary Visceromotor response --> ANS Somatic motor response --> cortex After Thanksgiving, why do I lose the weight without dieting? Is this related to yo-yo dieting?

Slide 3 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding Body Fat and Food Consumption Lipostatic hypothesis Parabiosis: E.g., Siamese twins Leptin Regulates body mass Decreases appetite Increases energy expenditure Leptin depletion Incites adaptive responses to fight starvation

Slide 4 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding The Hypothalamus and Feeding Anorexia Severely diminished appetite for food Can be caused by lesions in lateral hypothalamus (So normally the lateral hypothalamus correlates with hunger)

Slide 5 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding The Hypothalamus and Feeding Obesity Overeating. Can be caused by bilateral lesions in ventromedial hypothalamus (So normally, the ventromedial hypothalamus helps you feel satiated) arcuate n. part of this

Slide 6 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding The Hypothalamus and Feeding (Cont’d) Anorexia and Obesity

Slide 7 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding The Effects of Elevated Leptin Levels on the Hypothalamus Arcuate nucleus Located at the base of the third ventricle Activation of arcuate neurons that release αMSH and CART peptides Anorectic peptides- diminish appetite

Slide 8 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding The Effects of Elevated Leptin Levels on the Hypothalamus Activation of arcuate neurons that release αMSH and CART peptides (Cont’d) Project to hypothalamic regions that orchestrate coordinated response of: 1. Humoral response - paraventricular n. contains parvocellular neurons that project to ant. Pit. --> TSH, ACTH

Slide 9 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding The Effects of Elevated Leptin Levels on the Hypothalamus Activation of arcuate neurons that release αMSH and CART peptides (Cont’d) Project to hypothalamic regions that orchestrate coordinated response of: 1. Humoral response - paraventricular n. contains parvocellular neurons that project to ant. Pit. --> TSH, ACTH 2. Visceromotor response: ANS increases symp. NS

Slide 10 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding The Effects of Elevated Leptin Levels on the Hypothalamus Activation of arcuate neurons that release αMSH and CART peptides (Cont’d) Project to hypothalamic regions that orchestrate coordinated response of: 1. Humoral response - paraventricular n. contains parvocellular neurons that project to ant. Pit. --> TSH, ACTH 2. Viscero-motor response: ANS increases symp. NS 3. Somatic Motor Response: Inhibits lateral hypothalamus (hunger center)- projects to cortex

Slide 11 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Elevated Leptin levels: 2. visceromotor 1. humoral 3. somatic motor

Slide 12 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding The Effects of Decreased Leptin Levels on the Hypothalamus Activation of arcuate neurons that release NPY and AgRP Effects on energy balance: Opposite to the effects of αMSH and CART Orexigenic peptides– increase appetite 1. NPY and AgRP inhibit secretion of TSH and ACTH (humoral) 2. Activate parasympathetic division of ANS (visceromotor) 3. Stimulate feeding behavior (somatic motor)

Slide 13 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins The Effects of Decreased Leptin Levels on the Hypothalamus (Cont’d)

Slide 14 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding The Control of Feeding by Lateral Hypothalamic Peptides - (3. Somatic motor response) Lateral hypothalamus: Motivation to eat (hunger center) Electrical stimulation: Triggers feeding behavior in satiated animals Caveat MCH: Peptide nt Informs cortex about low leptin levels Motivates the search for food Orexin: peptide nt, also.

Slide 15 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Hormonal and Hypothalamic Regulation of Body Fat and Feeding Summary: The Effects of Elevated/Decreased Leptin Levels on the Hypothalamus A rise in leptin levels Increases αMSH and CART in arcuate neurons  inhibit feeding behavior and increase metabolism A fall in leptin levels Increases NPY and AgRP in arcuate and MCH neurons in lateral hypothalamus  stimulates feeding behavior and decreases metabolism (MCH, orexin)

Slide 16 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Summary Activity Take a few moments to look over your worksheet Identify questions you have Summarize in a table, in words, or out loud to your partner the long term regulation of feeding behavior without looking at your notes.

Slide 17 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins The Short-Term Regulation of Feeding Behavior Motivation to eat—depends on Time and quantity of last meal Appetite, Eating, Digestion, and Satiety 3 phases: Cephalic; Gastric; Substrate

Slide 18 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins The Short-Term Regulation of Feeding Behavior Appetite, Eating, Digestion, and Satiety Gastric Distension Cholecystokinin Insulin

Slide 19 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Why Do We Eat? Reinforcement and Reward Liking: Hedonic Wanting: Drive reduction Electrical self-stimulation: Experiments to identify sites of reinforcement Effective sites for self-stimulation: Trajectory of dopaminergic axons in the ventral tegmental area projecting to the forebrain Drugs that block dopamine receptors: Reduce self-stimulation

Slide 20 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Why Do We Eat? The Role of Dopamine in Motivation Old belief: Dopamine projection served hedonic reward New understanding Dopamine-depleted animals “like” food but “do not want” food Lack motivation to seek food, but enjoy it when available Stimulation of the dopamine axons Craving for food without increasing the hedonic impact

Slide 21 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Why Do We Eat? The Role of Dopamine in Motivation Serotonin, Food, and Mood Serotonin as a neurotransmitter Serotonin levels Low: Postabsorptive period Rise: In anticipation of food Spike: During meals Mood elevation Rise in blood tryptophan and brain serotonin

Slide 22 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Why Do We Eat? The Role of Dopamine in Motivation Serotonin, Food, and Mood (Cont’d) Drugs that elevate serotonin levels Example: Dexfenfluramine (Redux) Disorders: Anorexia nervosa; Bulimia nervosa  both often accompanied by depression Treatment Antidepressant drugs—elevate brain serotonin levels Example: Fluoxetine (“Prozac”)

Slide 23 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Other Motivated Behaviors Drinking Hypovolemia Decrease in blood volume Hypertonicity Increase in the concentration of dissolved substances in the blood Vasopressin: Antidiuretic hormone or ADH Acts on kidneys to increase water retention Inhibit urine production

Slide 24 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Other Motivated Behaviors Drinking (Cont’d) Volumetric thirst Thirst triggered by hypovolemia

Slide 25 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Other Motivated Behaviors Drinking (Cont’d) OVLT—vascular organ of the lamina terminalis Role of OVLT neurons Excite magnocellular neurosecretory cells Stimulate osmometric thirst Diabetes insipidus Treatment—replace missing vasopressin

Slide 26 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Other Motivated Behaviors Temperature Regulation Cells fine-tuned for constant temperature— 37°C (98.6ºF) Neurons for temperature homeostasis Clustered in anterior hypothalamus Humoral and visceromotor responses Neurons in the medial preoptic area of the hypothalamus Somatic motor (behavioral) responses Neurons of lateral hypothalamic area

Slide 27 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Other Motivated Behaviors Temperature Regulation (Cont’d) Process during a fall in temperature: Visceromotor response: Goosebumps Involuntary somatic motor response Shivering, seeking warmth Rise in temperature: Metabolism slowed by reducing TSH release TSH released by anterior pituitary TSH stimulates release of thyroxin from thyroid gland Increase in cellular metabolism

Slide 28 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Other Motivated Behaviors Temperature Regulation (Cont’d) Hypothalmic responses to stimuli that motivate behavior

Slide 29 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins Concluding Remarks Overview of motor systems Addressed “how” questions of behavior E.g., How is movement initiated? Overview of motivation systems Addresses “why” questions of behavior E.g., Why do we drink when dehydrated? The important discovery of a neural basis for feeding behavior Allows us to frame new questions that will impact how we view our own behaviors

Slide 30 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins End of Presentation