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a control process that is what happens when you have to decide what enters memory and what is ready to be ejected
how do we prevent ourselves from doing things that are contextually inappropriate; poster child of control processes
the ability to inhibit an unwanted motor response
inhibition tasks (3)
1) anti-saccade inhibition task: composed of two signals: with the pro-saccade signal you make an eye movement toward a target, and with the anti-saccade signal you have to make a saccade to the direction OPPOSITE of a dot (target)
- 2) go –no go tasks: one stimulus indicates a response, the other indicates the inhibition
- of a response; ex: target comes on, and you press a button OR different target comes on and you DON’T press a button
3)countermanding: you practice looking at a FP, then making a saccade to a target; however sometimes a tone or the reappearance of the FP signals you to NOT make the saccade
patients with _______ lobe lesions ____ to inhibit a [reflexive] saccade to the target in a do the anti-saccade task
Point of the Race Model in terms of the COUNTERMANDING task
okay so you know that the reaction time of a certain neuron depends on whether an eye movement is made or inhibited (example of the horserace, if the saccade neuron reaches its threshold 1st then an eye movement will be made but if a fixation neuron reaches it's threshold first it will inhibit the saccade); the point of this is that if you present enough trials with the stop signal at different times before planning/saccade, then you can predict what the outcome will be of a trial depending on when the signal is given!
inhibition failure vs. success (countermanding)
in an example of an inhibition failure trial, the go signal is given at a certain time, so the animal is planning on making an eye movement and the STOP signal is just given too late for the fixation neurons to reach their threshold before the saccadic ones do; contrastingly, in a success trial, the stop signal is given in enough time for the fixation neurons to QUICKLY (have a huge spike in RT) reach their threshold, fire, and prevent movement
supplementary eye fields (SEF)
the source of top-down, executive control signaling of eye movement; don’t show the same pattern of activity as FEF (which controls saccades); it PROJECTS to the FEF; just know that during anti-saccade tasks the FEF has the highest activation when succeeding (next highest is during failing) to make an antisaccadic eye movement; in countermanding tasks, SEF has the highest activity when attempting to inhibit a saccade (aka when the stop signal comes on too late and an eye movement is mistakenly made)
DLPFC in antisaccadic trials
the area doesn’t care where you’re looking; you train an animal to do anti and pro saccades, neurons will simply track the type of task the animal’s doing (there's constant activation); the only time there's a dip in firing in when there's a change from a pro to anti or anti to pro saccadic response; dip is correlated with the proportion of correct responses (in layman's terms, when the monkey has gotten used to performing one type of task (ex: saccadic) and has to quickly change to another, they will probably get that first transfer trial wrong, and it is HERE we see a dip in DLPFC activity)
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