Psyc4130 1nd Edition Lecture 24 Outline of Last Lecture I Corpus Callosum II Brain Imaging III Insular Cortex IV Cortical Structures V Amygdala VI Amygdaloid Complex VII Amygdala as Fear Factor VIII Cracking the Nut IX Central Nucleus Outline of Current Lecture I II III IV V VI VII VIII Cracking The Nut Noteworthy Brain Regions Obliterates Conditioned Emotional Responses Lesions of vmPFC Spontaenous Recovery Rapid Reacquisition Toxoplasmosis in Rodents Kluver Bucy Syndrome Humans with Amygdala Damage Current Lecture Cracking the Nut After the CE has been destroyed animals no longer show signs of fear when confronted with stimuli that have been paired with aversive events Central nucleus is key to auntonomic response Noteworthy Brain Regions Later hypothalamus o Sympathetic activation increase heart rate and blood pressure paleness Ventral tegmental area o Behavioral arousal dopamine o Dopamine becomes active when animals escapes from stressful situation These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o Motivate fleeing or escape behaviors in present context Locus Coeruleus o Norepinephrine o Increased vigilance Periaqueductal Gray Matter o Behavior arrest freezing Obliterates Conditioned Emotional Responses Rats ethical validity Figure 11 3 o Rat exposed to tone plays for 9 5 seconds then zap o Pavlovian conditioned stimuli aversive conditioning vmPFC can come to inhibit aka override CE dyring extinction of CER o Reciprocally connected and mutually inhibitory suppress one another o The more active the amygdala is the vmPFC becomes less active o Inhibitory effects of vmPFC on amygdala practically cognitive behavioral therapies Identify irrational fears self dialogue fear of negative evaluation public speaking inflated unrealistic Figure 11 4 control of extinction o This graph shows the positive correlation b w activation of the medial prefrontal cortex and establishment of extinction o Administer tone but don t administer shock o Measure of extinction of success how powerfully strong is the absence of the conditioned fear response Lesions of vmPFC Lesions of vmPFC impair extinction ECB s in amygdala required for extinction o Might have to do with self medication in violent unpredictable environments inner cities opiates etc Does extinction forgetting o No connection isn t forgotten o Reinstated full power of association is now much easier to do don t have to do as many trials Spontaenous Recovery Rapid Reacquisition Learned phenomenon has not been forgotten Extinction training has suppressed response but not erased it Toxoplasmosis in Rodents Toxoplasma gondii is a protozoan parasite that reproduces in the gastrointestinal track of cats Infected cats release the Toxoplasma eggs when defecating Burrowing rats may become infected The parasite migrates to the rat s brain where it selectively destroys the amygdala Infected rats fail to avoid the cat starts cycle again Kluver Bucy Syndrome Bilateral ablation of amygdala Become tame and placid Unusual for monkeys Abnormal absence of fear for stimuli that monkeys usually find intimidating o Snakes fire dominant monkeys Humans with Amygdala Damage Emotion is generally intact Struggle interpreting subtle emotional cues or complex emotional situations Equally likely to remember minor details or emotional gist of a story Judgments of trustworthiness e g strangers in strange situations are markedly skewed from normal o Tend to be trustful from everyone Think of it as a broken sketch radar But the amygdala especially in the human brain is much much more than a fear factor The human amygdala is maximally responsive when additional emotion processing is required in order to interpret a situation o Esp social situations e g facial expressions and gaze Adams et al 2003 o Looking at pictures of emotional expressions activates amygdala but the response is not specific for fear Gaze aversion looking up vs looking straight at you
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