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Elizabeth Lorenc, Mark D'Esposito; Neural mechanisms of precision in visual working memory for faces. Journal of Vision 2017;17(10):345. doi: 10.1167/17.10.345.
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© ARVO (1962-2015); The Authors (2016-present)
Visual working memory (VWM) allows for the maintenance and manipulation of information about objects no longer in view. Interestingly, the precision with which visual information can be encoded, maintained, and retrieved from VWM varies considerably between healthy individuals, and even from trial to trial within a single individual. We hypothesize that a stimulus-selective area such as the fusiform face area (FFA) supports precise VWM by maintaining perception-related activity when a visual stimulus is no longer present. To that end, we trained an encoding model on perception-related activity patterns, and then inverted the model to reconstruct face VWM representations in the FFA and early visual areas. Functional magnetic resonance imaging data was collected while participants performed a delayed-estimation task for faces. On each trial, a post-cue indicated whether the participant should store the item through a 10s delay period ('Store") or discard it from memory ("Drop"). "Store" trials ended with a method-of-adjustment response in which a random face was morphed to match the remembered face, and "drop" trials ended with a perceptual matching task in which a probe face was morphed to match a simultaneously-presented test face. We found that faces could reliably be reconstructed from both the early visual and FFA regions of interest during perception, before the "store" or "drop" post-cue. Interestingly, reliable face reconstructions persisted in both V1-V3 and the FFA through the memory delay, when a participant was actively holding a face in memory. However, we found the opposite in the "drop" trials; delay activity patterns were anti-correlated with those at perception, yielding negative population tuning curves. Future analyses will investigate the role of the lateral prefrontal cortex in sustaining perception-related activity when a face stimulus is actively maintained in working memory, and in suppressing that activity when maintenance is not required.
Meeting abstract presented at VSS 2017
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