The sensory nature of mnemonic representation in the primate prefrontal cortex

The sensory nature of mnemonic representation in the primate prefrontal cortex Constantinidis Franowicz Goldman-Rakic

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The sensory nature of mnemonic representation in the primate prefrontal cortex 2001 Nature Neuroscience 10.1038/85179 Constantinidis2001-the-sensory-nature-of-mnemonic-representatio Constantinidis2001-the-sensory-nature-of-mnemonic-representatio.txt, the project's staged copy 5144ec3387f711d03cbd0e0d2d6504ffc7394ffe not-redistributable neuroscience

the paper's own words

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0 spans located by searching the stored text for the quote's exact words, allowing any whitespace between them existence Quotation withheld because this record is not cleared for redistribution. delay-period activity in primate prefrontal cortex during visual working memory Quotation withheld because this record is not cleared for redistribution. electrophysiology electrophysiology Quotation withheld because this record is not cleared for redistribution. mechanisms Dorsolateral PFC runs two superimposed processes - a slowly decaying sensory representation plus a response-preparation signal that ramps toward the saccade - whose sum produces the observed delay activity status: the paper's own words: we propose that Quotation withheld because this record is not cleared for redistribution. mechanisms The motor plan emerges from a network of neurons that keep holding sensory information, rather than from a discrete sensory-to-motor transformation stage in single neurons Quotation withheld because this record is not cleared for redistribution. The task never required luminance itself to be remembered, only the relative comparison what this limits: any claim that the animals held LUMINANCE in memory: OUR TASK DID NOT EXPLICITLY REQUIRE THE ANIMALS TO REMEMBER THE LUMINANCE OF THE STIMULI; THE SUBJECT NEEDED ONLY TO DISCRIMINATE BETWEEN THEIR RELATIVE DIFFERENCE Quotation withheld because this record is not cleared for redistribution. Not all recorded neurons fitted the sensory account; some reflected only the motor response what this limits: the sensory account of the population: WE DID OBSERVE SOME NEURONS, PARTICULARLY THOSE WITH STRONG PRE-SACCADIC RESPONSES, THAT ONLY REFLECTED THE ANIMAL'S MOTOR RESPONSE Quotation withheld because this record is not cleared for redistribution. The two results on the same measure hold under opposite spatial conditions. what this limits: any summary of what modulates delay period activity here: it was not significantly modulated by a distractor outside the receptive field when the target was inside, and was significantly dependent on contrast ratio when the distractor appeared inside the receptive field Quotation withheld because this record is not cleared for redistribution. The inference the whole result rests on is reported by the authors as contested. what this limits: the claim that this delay activity is memory: the authors report the argument Quotation withheld because this record is not cleared for redistribution. The analysis population was chosen by an explicit decision not to exclude two neuron types. what this limits: any population statistic reported here: the authors based the analysis on the entire sample rather than ignoring the contribution of primarily cue and saccade neurons to delay period activity Quotation withheld because this record is not cleared for redistribution. eye-movement parameters as the cause of the contrast-ratio effect eliminates: the reading that the contrast dependence is an artefact of where the animal looked · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. delay period activity delay period activity Quotation withheld because this record is not cleared for redistribution. distractor distractor Quotation withheld because this record is not cleared for redistribution. contrast ratio contrast ratio Quotation withheld because this record is not cleared for redistribution. receptive field receptive field Quotation withheld because this record is not cleared for redistribution. perceptual memory perceptual memory Quotation withheld because this record is not cleared for redistribution. delay period activity - MODULATED OR NOT DEPENDING ON WHERE THE STIMULI WERE: not significantly modulated by a distractor outside the receptive field while the target was inside, and significantly dependent on contrast ratio when the distractor was inside it; the same measure yields a null and a positive result, and only the spatial condition separates them Quotation withheld because this record is not cleared for redistribution. delay activity as memory - AN INFERENCE THE PAPER REPORTS AS DISPUTED: neurons discharge while a stimulus is held in memory, and it has been argued that temporal correlation does not necessarily imply involvement of that activity in perceptual memory, so the field's central inference is named as contested inside a paper that relies on it Quotation withheld because this record is not cleared for redistribution. the analysed sample - THE WHOLE RECORDING, BY DECISION: rather than dropping neurons whose responses were mainly to the cue or the saccade, the authors state they used the entire sample so as not to ignore those neurons' contribution to delay period activity Quotation withheld because this record is not cleared for redistribution. contradicts → previous studies of delay-period activity in a discrimination task concluding that responses reflect the outcome of a perceptual decision (the paper's refs 18,19) Quotation withheld because this record is not cleared for redistribution. builds-on → previous dorsolateral prefrontal experiments using the anti-saccade paradigm, spatial match-to-sample and conditional response tasks (the paper's refs 10,28,29) Quotation withheld because this record is not cleared for redistribution. distractor —causes→ delay period activity distractor delay period activity holds when: when the distractor is outside the receptive field and the target inside it · direction on the measure: no-change · strength of the relation: 1 Quotation withheld because this record is not cleared for redistribution. contrast ratio —causes→ delay period activity contrast ratio delay period activity holds when: when the distractor appeared in the receptive field · strength of the relation: 1 Quotation withheld because this record is not cleared for redistribution. t-test t-test Quotation withheld because this record is not cleared for redistribution. regression regression Quotation withheld because this record is not cleared for redistribution. linear regression linear regression Quotation withheld because this record is not cleared for redistribution. ANOVA ANOVA Quotation withheld because this record is not cleared for redistribution. ROC analysis ROC analysis Quotation withheld because this record is not cleared for redistribution. coefficient of determination coefficient of determination about this quote: THE QUOTE STOPS WHERE THE PAGE ENDS: the sentence breaks mid-word after 'respec' (for 'respectively') into the page footer and a figure, and it resumes only after them, so the bracket it opened is not closed inside the quote. Quotation withheld because this record is not cleared for redistribution. p-value p-value Quotation withheld because this record is not cleared for redistribution. Delay-period activity depended significantly on contrast ratio when the distractor appeared in the receptive field. Quotation withheld because this record is not cleared for redistribution. Mnemonic prefrontal activity was directly correlated with the monkeys' psychophysical performance. Quotation withheld because this record is not cleared for redistribution. Neuronal discriminability between target and distractor tracked contrast ratio across the entire delay, not only early in it. Quotation withheld because this record is not cleared for redistribution. Contrary to that account's prediction, responses stayed graded by luminance throughout the delay. Quotation withheld because this record is not cleared for redistribution. The effect was significant for 42% of the neurons (45% and 25% in the two animals). Quotation withheld because this record is not cleared for redistribution. The contrast effect was significant across the population when the distractor was in the receptive field but not when the target was, as with the fixed delay. Quotation withheld because this record is not cleared for redistribution. Reward expectation cannot explain the pattern, because firing was strongest in the condition of minimum expected reward. Quotation withheld because this record is not cleared for redistribution. area under the ROC curve area under the ROC curve Quotation withheld because this record is not cleared for redistribution. short-term memory trace short-term memory trace Quotation withheld because this record is not cleared for redistribution. working memory working memory Quotation withheld because this record is not cleared for redistribution. contrast ratio contrast ratio Quotation withheld because this record is not cleared for redistribution. firing rate firing rate Quotation withheld because this record is not cleared for redistribution. percentage of correct saccades percentage of correct saccades Quotation withheld because this record is not cleared for redistribution. saccade metrics saccade metrics Quotation withheld because this record is not cleared for redistribution. 52 — isolated prefrontal neurons analysed in the fixed-delay experiment, from two rhesus monkeys Quotation withheld because this record is not cleared for redistribution. 75% — behavioural accuracy threshold, reached at a distractor/target contrast ratio of 1-4% Quotation withheld because this record is not cleared for redistribution. 42% — proportion of neurons with significantly elevated delay activity for a distractor in the receptive field Quotation withheld because this record is not cleared for redistribution. 24 — additional neurons recorded in the variable-delay control experiment Quotation withheld because this record is not cleared for redistribution. –0.037, p < 10–5 — regression slope of normalized delay firing on log contrast ratio when the distractor was in the receptive field Quotation withheld because this record is not cleared for redistribution. R2 = 0.99, 0.97 — fit of psychophysical performance to the logarithm of contrast ratio for the two monkeys about this quote: THE QUOTE STOPS WHERE THE PAGE ENDS: the sentence breaks mid-word after 'respec' (for 'respectively') into the page footer and a figure, and it resumes only after them, so the bracket it opened is not closed inside the quote. Quotation withheld because this record is not cleared for redistribution. F66,4284 = 0.57, p > 0.9 — non-significant time-by-contrast interaction in the ANOVA on ROC discrimination probability Quotation withheld because this record is not cleared for redistribution.

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