BIOL 320 Lecture Notes - Lecture 8: Walter Mischel, Claustrum, Stroop Effect
DVR: is it homologous to neocortex or to claustrum/amygdala?—
All the pink areas are where tbr-1 & emx-1 are expressed; tbr-1 also expressed in dark orange
Striedter: claustrum & amygdala —
Review of last class•
So in mammals, things that express emx-1 become neocortex
So because of similarity between expression, you could argue that dark orange would be homologous to ventro-
pallium and eventually develop into amygdala because of the similarity between expression
Marshmallow test: so fckn cute
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He followed some of the kids through adolescence and adulthood
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found that tendencies toward impulsivity vs.
restraint remains consistent throughout ages
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High delayers were less impulsive—
Then put them into scan—fMRI—to perform similar version; had to do "go/no go" task (resist pushing a button)—
IFG showed increased activity when subjects had to refrain from hitting button
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separates it from a purely motor
response
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Based on a study by
Walter Mischel (1972)
: goal was to test 4yos to test ability to delay gratification—"you can wait before
eating marshmallow to get even greater reward (a 2nd marshmallow)"
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PRE
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FRONTAL CORTEX
8. PFC
January 31, 2018 11:38
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So there's greater activity in go on other areas—
So nogo activity in IFG suggests involvement in showing restraint—
And high delayers (at 4yo) had bigger change in activity in IFG vs. the ones that didn't show restraint—
So we can take this beyond the marshmallow
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So obviously the PFC does a lot more!•
So Stroop test (say the colour of the word) CONFLICT BETWEEN COLOUR AND WORD, makes the task a lot harder,
reaction time is slower; need to shut down impulse to read the word
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sensory-guided/habitual response needs to be
suppressed in favour of memory-guided or conceptual response
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this requires work in PFC
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Encoding rules, categories, principles—PFC seems to provide top-down, cognitive control, sometimes called
executive
function
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Not involved in stimulus response—but generating proper behaviour in a particular environment; it might also be involved in
representing information that is not currently in the environment
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Categorise dog or cat after a delay—
Requires categorisation and remembering it over a period of time and respond when it is no longer present
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hold it in
your memory
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requires PFC
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Matching task•
Categorical perception: provides useful groupings and divisions not present in external world; doesn't track sensory input but
retains perceptual categories with sharp boundaries
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E.G. if you play continuous tone across different frequencies to a cricket: if you play anything below 16kHz, will treat as mate
and will approach; anything above 16kHz, will avoid because they think it's a predator
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division is quite sharp!
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It can be difficult to create a categorical stimuli to find this sort of behaviour—
Finding the right categories to change in animals is a bit of a challenge—while stimuli should be categorically different, the
boundary should be similar and within a category, the stimuli should vary in appearance
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Multiple types of both cats & dogs; for each, they would morph them (so go from 100% cat and then slowly turn it into a
wolf)—gradually morph each species into another
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So there's a lot of variation between each category, and small, seamless changes between both—
So they had stimuli that looked like this:
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Miller & Freedman (2001)
: used novel approach to create 2 stimulus categories = cats & dogs•
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