LECTURE 23: EMOTIONS, MOTIVATION, AND DRUGS OF ABUSE REQUIRED READING: Kandel text, Chapters 50, 51 Emotion and Feeling are two interconnected states. Emotion Emotion is a group of physiological and motor responses to a set of stimuli. These emotional responses communicate our state to others, prepare us or drive us for consequent action, and have powerful effects on our unconscious (implicit) unconscious (implicit) memory of the stimulus events. Feelingconscious (explicit) Feeling represent the conscious (explicit) awareness of our emotional state. EXAMPLES: emotion The taste of a great dessert can elicit the emotion of enjoyment and feeling satisfaction and the feeling of having something delicious emotion Upon hearing a joke, one may experience the emotion of laughter feeling and the feeling of a funny experience EMOTIONS EXERT POWERFUL INFLUENCES ON MOTIVATIONAL BEHAVIOR

EMOTIONAL EXPERIENCES CAN BE STEREOTYPICAL OR SUBJECTIVE startle emotion Hearing an unanticipated loud explosion triggers a startle emotion characterized by heightened awareness, shivering or freezing, elevated pulse and blood pressure, and a specific facial expression, feeling of fear while triggering the feeling of fear Seeing David Ortiz of the Boston Red Sox hit a home run against exhaltationsadness the New York Yankees can trigger exhaltation, sadness, nothing or nothing depending upon one’s interest in baseball and whether one is a Red Sox or Yankees fan Why?: Just as conscious cortical activity can shape our reflexive responses to stimuli, it can also shape our automatic emotional responses to certain stimuli Conscious decisions can shape value (ethical) judgments which inform our emotional responses

THE LIMBIC SYSTEM CONTROLS GENERATION OF EMOTIONAL STATES

THE AMYGDALA IS CRITICAL FOR EMOTIONAL RESPONSES, PARTICULARLY TO NEGATIVE EMOTIONS

LEARNED EMOTIONAL RESPONSES ARE PROCESSED IN THE AMYGDALA

AMYGDALA AND HIPPOCAMPUS ARE SEPARATELY NEEDED FOR THE FEARFUL AND COGNITIVE COMPONENTS OF PAST EXPERIENCE Individuals with brain lesions were shown different colored slides, and some slide colors were followed by a loud startling noise LESION CONSCIOUS MEMORY LEARNED FEAR OF COLORS OF COLORS NONE YES YES AMYGDALA NO AMYGDALA YES NO HIPPOCAMPUS NO HIPPOCAMPUS NO YES BOTH NO NO

DEAZOPENE (VALIUM) INHIBITS FEAR AND ANXIETY Valium is a widely used medication used to reduce anxiety and fear, often prescribed prior to surgeries without general anesthesia Valium interacts with GABA ionotropic receptors, and enhances GABA-induced chloride conductance. At optimal dosages, valium inhibits firing of neurons in fear and anxiety circuits Valium is often used, often addictively, as a means to relieve “life” stress

MOTIVATIONAL BEHAVIORS ARE OFTEN DIRECTED TOWARDS MAINTENANCE OF PHYSIOLOGICAL HOMEOSTASIS The hypothalamus plays a pivotal role in homeostatic motivations, acting as physiological sensor and coordinating autonomic and motivational responses Examples: Thermal regulation: Thermal regulation: Certain hypothalamic neurons fire at different rates at different temperatures. Deviation from set point (37 o C in humans) triggers other regions of hypothalamus initiate autonomic functions and behavioral drives Appetite: Appetite: Hunger level is driven in part by hypothalamic control. Certain hypothalamic neurons have receptors for a hormone, leptin leptin, which is produced by fat tissue. Leptin suppresses apetite.

SOME MOTIVATIONS ARE NOT DRIVEN BY DIRECT PHYSIOLOGICAL NEEDS, BUT BY PLEASURABLE EMOTIONS AND ANTICIPATION OF PLEASURE We (and rats) tend to eat more calories of flavorful food than bland diet Sexual behavior is drive towards pleasure fulfillment Stimuli that are pleasurable are believed to signal “pleasure” by activating certain midbrain dopaminergic neurons in the ventral tegmental area (VTA) that project to the nucleus accumbens (NA) region of the forebrain Rats can be implanted with electrodes into the VTA, with stimulation triggered by the animals pressing a lever. Such animals learn to frequently self-”reward” by pressing the lever

MANY DRUGS OF ABUSE ACT BY PROMOTING THE DOPAMINERGIC PLEASURE CIRCUIT Cocaineamphetamines Cocaine and amphetamines act by blocking dopamine reuptake transporters, resulting in prolonged dopaminergic signaling. These drugs cause sensory-independent sensation of pleasure and also enhance pleasure associated with certain stimuli Nicotine Nicotine mediates excess release of VTA dopamine by stimulating presynaptic cholinergic receptors on VTA axons Mu opiates Mu opiates (e.g., morphine) act by inhibiting GABAergic neurons that project to VTA dopaminergic neurons

DRUG CRAVING CAN BE TRIGGERED BY SENSORY CUES ASSOCIATED WITH DRUG USE: A FORM OF CONDITIONED STIMULUS Drug exposure follows a sequence of behavioral and sensory cues that act as conditioning stimuli to the drug unconditional stimulus Consequence is conditioned response, whereby the cues alone trigger anticipation of drug “reward”