Lecture 11: Emotions and stress
Lecture 11: Emotions and stress NSC 3361
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This 7 page Class Notes was uploaded by Rachael Couch on Tuesday February 16, 2016. The Class Notes belongs to NSC 3361 at University of Texas at Dallas taught by Van S Miller in Summer 2015. Since its upload, it has received 44 views. For similar materials see Behavioral Neuroscience in Neuroscience at University of Texas at Dallas.
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Date Created: 02/16/16
Lecture 11: Emotions Neural basis of emotions Not completely understood Multiple areas of brain act together in any given emotion Some areas, though, are of prime importance fMRI studies have been key Model of emotion 2 axes/dimensions of emotion o 1) “X axis” avoidance versus approach behavior Does the behavior make the individual go towards or away from the stimulus o 2) “Y axis” Level of arousal (intensity of emotion) o Ex: on the moderate avoidance site, with increasing arousal dislike contempt hatred Emotion is an increase or decrease in physiological activity accompanied by feelings characteristic of the emotion Stimulus cognitive appraisal effects o Ex: Stimulus seeing a man with a knife cognitive appraisal your brain registers it as “danger” effects – autonomic nervous system (ANS) reacts (heart rate, breathing), behavior changes (run), facial expression changes, emotional feelings change (fear) Feedback the behavioral, ANS effects, and facial expression feed the emotional feelings which then feeds cognitive appraisal Emotions and culture Only 8 emotions but there are variations in intensities of them o Emotions are “pancultural” which suggests that there are 8 biological emotions How we deal with these emotions is cultural Each emotion has a characteristic facial expression Across cultures: o An elicitor (stimulus) causes an emotion (pancultural) o This is mediated by culturespecific display rules which lead to an end result o Ex: Biological joke stimulates the limbic system to laugh (happiness) Cultural – you’re in church so the frontal cortex suppresses the laugh Facial expressions Impairment limits social interaction o Parkinson’s disease, schizophrenia, facial nerve paralysis o Moebius syndrome genetic condition that causes facial paralysis Girl cannot smile, but chin is slightly tilted up, her mother can tell she’s happy but other children probably cannot o Bell’s palsy Face is half paralyzed (asymmetric); cannot tell her emotion Facial feedback o The brain monitors facial expression to know how to feel o Posed expressions (“fake smile”) produce the intended emotion, and the associated physiological arousal; so we can create our own emotion o Changing motoric activity alters behavior and thinking “Selfdelusion goes a long way in life” o Posed expressions affect how we interpret our environment A stimulus is more painful when making a sad face Cartoons are rated as funnier during induced smiling Women given Botox are less able to frown and have less negative mood When they are told to imitate an angry expression they have less amygdala activity – can’t generate anger because they can’t frown Brain areas Brainstem (“power”) Controls the intensity of the emotion Locus coeruleus – site of norepinephrine synthesis o Emotional arousal, depression, stress; moderate/contented pleasure VTA, substantia nigra o Dopamine pleasure, exhilaration Orbitofrontal cortex (“controller”) = The bottom part of the frontal lobe/cortex; right on top of the eyes = prefrontal/frontal lobe Inhibits raw emotion from the amygdala Increased activation from increased “shock value” of material o Cursing = violation of social norm = funny Laughter activates the orbitofrontal cortex Prefrontal (orbitofrontal) cortex Final destination for much of the brain’s information about emotion before action is taken Judges our behavior and its consequences o Ex: You want to laugh but you’re in church so your prefrontal cortex suppresses it – judges the appropriateness of your behavior Damaged understand moral and social rules but can’t apply the rules in their own lives Damage early in life never learn these rules and are motivated only to avoid punishment Abnormalities in PFC are associated with aggression, depression, and schizophrenia Limbic system (“integrator”) Takes information from different sources (visual, environmental, ANS reactions) and decides Ex: man with knife is scary in a dark alley but not in an acting class o “Same stimulus different appraisal” because of a different judgement made by the limbic system Hypothalamus ANS reactions (heart rate, pupils, etc.) Amygdala – fear (and aggression – the related behavior o Participates in memory formation, especially emotional ones and recognition of fear in other people In fMRI, posed fearful expression amygdala activation o People with amygdala damage are unusually trusting o Anxietyreducing drugs act on receptors in the amygdala Hippocampus memory (emotional, spatial) o Memory is important in emotion because experience determines the severity of the situation Ex: The man with the knife is someone you know who told you that if he saw you again he’d kill you Cingulate gyrus (= anterior cingulate cortex/empathetic nervous system) o Pain processing (the pain sensation and the emotion generated from that pain) o Combines emotional, attentional, and body information in a conscious emotional experience o Empathy Sensory cortex activated when being touched physically and when watching a movie of someone being touched Other emotions Pleasure/happiness Related to craving and addiction Medial forebrain bundle – tract rises from midbrain through the hypothalamus; contacts the locus coeruleus, VTA, and nucleus accumbens to the brain o Contains many sites for selfstimulation Surprises Involves the nucleus accumbens (NAC) addiction Unexpected surprises more activation of nucleus accumbens than expected reward Klüver–Bucy syndrome Removal of temporal lobes in monkeys socially unacceptable behavior o Failure to recognize other’s emotions Studies showed that the amygdala, in the temporal lobe, is a key structure in fear Stimulus acts on sensory organs (eyes) that activate the thalamus, sensory cortex, and hippocampus o Signal goes into amygdala emotional behavior, hormonal response and hypothalamus to stimulate autonomic responses o The amygdala is the link between the hippocampus and emotional behavior (hypothalamus) Disgust (moral disgust) and guilt (inward disgust) activate the insula Romantic love Students in new love were scanned while looking at a photo of their beloved Right caudate (connected to nucleus accumbens), ventral tegmental area (involved in drug craving) became very active Love or lust? – studied older people; couples who have been together for 50 years,etc. o Discovered that these “lust” areas do not light up Septal stimulation produces pleasure, accompanied by sexual fantasies and arousal o Septal nucleus (limbic system) o Involved in all fantasies (related to empathy) Two hemispheres Left side of the face (controlled by right hemisphere) is more expressive than the right o right brain is more emotional Hemispheres differ in comprehending vocal messages o Right hemisphere identifies tone Ex: processes sarcasm o Left hemisphere processes the words (meaning of the message) Left frontal lobe activation o Behavioral approach o Emotions regulated by this area are anger and joy o More active during positive emotions o Compassion meditation affects left frontal lobe o Damage to the left hemisphere anxiety and sadness Right frontal lobe activation o Behavioral withdrawal o Emotions regulated are fear, sadness o More active during negative emotions o Righthemisphere damage – patients more likely to be unbothered or euphoric, even if their arm or leg is paralyzed Aggression Bullies find sadism rewarding/addictive In aggressive teens, areas of brain linked with feeling reward (amygdala and striatum) become active when they watch pain inflicted on others o Striatum = nucleus accumbens Stress Stress response activates the sympathetic nervous system, largely under hypothalamic control Resulting increases in heart rate, blood flow, and respiration rate help the person deal with the situation Activates many bodily responses Adrenal cortex (adrenal glands) secretes cortisol o Cortisol is a stress hormone that increases blood glucose and breaks down protein Adrenal medulla releases epinephrine and norepinephrine Autonomic activation during a stressful situation o high cortisol, low testosterone, and high epinephrine o Before the stressful situation (they’re afraid) levels are high o Rapidly rise and rapidly adapt after a situation Hormonal response o Increased epinephrine during a crowded train ride o Surge in ep and norep during exam – goes down after Acute Stress Hypothalamus and pituitary stimulate adrenals to release: o Epinephrine and norepinephrine Increase output from the heart and free glucose o Cortisol provides sustained release of energy to cope Beneficial o Immune system is boosted o Brain build new neurons – prepares you to defend yourself Harmful can lead to heart attacks Chronic stress Interferes with memory, appetite, sexual desire and performance, energy, and mood Compromises the immune system o Hormones released (noradrenaline) suppress the immune system PTSD develops in response to an exceptionally stressful (catastrophic) event o Usually onset a few days after event o Involves limbic system (amygdala fear) o Symptoms include reexperiencing (flashbacks, nightmares), avoiding people or situations associated with event, hyperarousal symptoms (panic, increased heart rate) o After 7 years, 40% of those diagnosed still have it o Many recover without treatment o Treatments Behavioural desensitization – repeatedly exposing to triggers; people often stop going because treatment is stressful Propranolol – may help block memory of event Ecstasy – similar to SSRI but much more potent Treatment eliminates about 20% Brain changes and damage Damage (reduced volume) in the frontal cortex and hippocampus (temporal lobe) o Frontal cortex is involved in executive function Damage inappropriate behavior (abuse, etc.) Cycle of abuse – abuse causes damage, makes one more likely to abuse their child which causes frontal cortex damage, etc. Reduced cortical tissue Amygdala enlarges at first and then later atrophies Damage due to stress is caused by cortisol perhaps increased receptor sensitivity Social/personality influences have a physiological basis Introverts (social anxiety) with HIV have higher virus titers than extroverts with HIV o Norepinephrine (NE) levels are higher in introverts; NE blocks immune system Subjects who had higher activity in the left hemisphere (associated with positive emotions) had a better response to the flu shot Biological origins of aggression Aggression – behavior that is intended to harm; not always physical 2 types of aggression (reactive and proactive) involve different brain areas Reactive aggression is impulsive, provoked, emotional, and unplanned o Ex: road rage, murderers o Lower activity in prefrontal cortex o Less gray matter in prefrontal cortex associated with antisocial personality disorder o Behave recklessly, overreact to provocation, and are sexually promiscuous Proactive aggression is premeditated, unprovoked, emotionless o Ex: Boston bombers, planned killings o Associated with psychopathy Sociopaths are incapable of remorse – they may commit very violent acts o Less autonomic response to stress o Impaired amygdala function Hormones o Testosterone levels are higher in men convicted of violent crimes, as well as in aggressive women prisoners Women have hormones that have androgenlike effects o Aggression and competition (winning) can increase testosterone o Testosterone rise also increases dopamine – aggression/winning can be addictive Brain areas o Murderers have higher activity of the amygdala and hypothalamus o Removing the amygdala reduces aggression in 33100% of patients o Tumors in amygdala, hypothalamus or septal area can cause aggression o Seizure activity in the amygdala increases aggression Case studies Case: Bob Head trauma – chronic traumatic encephalopathy Injured orbitofrontal cortex Doesn’t feel emotion, can’t sense wife’s emotions anymore Brain scan shows white spots at the temporal lobes Case: Klüver–Bucy syndrome 6yearold boy was hospitalized because of seizures. First 3 days fatigue, incoherent speech, hallucinations, verbal agnosia (couldn’t understand language), and weird behaviors One month later lost speech and developed visual agnosia, and memory deficits His aggression increased and he became hyper oral (put everything in his month like a 6 month old would do( Motoric activity was unstable – either would be bouncing off the wall or doing nothing at all Case: aggression 13 y/o old boy made multiple suicide attempts and attempted violent acts against others He was placed in restraints up to 6 hours per day Cut out part of his amygdala
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