Psyc4130 1nd Edition Lecture 24 Outline of Last Lecture I. Corpus CallosumII. Brain ImagingIII. Insular CortexIV. Cortical StructuresV. AmygdalaVI. Amygdaloid Complex VII. Amygdala as “Fear Factor”VIII. Cracking the NutIX. Central NucleusOutline of Current Lecture I. Cracking The NutII. Noteworthy Brain RegionsIII. Obliterates Conditioned Emotional ResponsesIV. Lesions of vmPFCV. Spontaenous Recovery & Rapid ReacquisitionVI. Toxoplasmosis in RodentsVII. Kluver-Bucy SyndromeVIII. 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 hypothalamuso Sympathetic activation, increase heart rate, and blood pressure, paleness- Ventral tegmental areao Behavioral arousal (dopamine)o Dopamine becomes active when animals escapes from stressful situationThese 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 Coeruleuso Norepinephrineo Increased vigilance - Periaqueductal Gray Mattero Behavior arrest (freezing) Obliterates Conditioned Emotional Responses- Rats= ethical validity- Figure 11.3o Rat exposed to tone plays for 9.5 seconds then zapo Pavlovian conditioned stimuli (aversive conditioning)- **vmPFC can come to inhibit (aka override) CE dyring extinction of CERo Reciprocally connected and mutually inhibitory (suppress one another)o The more active the amygdala is, the vmPFC becomes less activeo 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 extinctiono This graph shows the positive correlation b/w activation of the medial prefrontal cortex and establishment of extinctiono Administer tone but don't administer shocko 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 forgotteno 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 ofcats.- 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 intimidatingo 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 normalo 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 situationo 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
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