Feedback Scales the Spatial Tuning of Cortical Responses during Both Visual Working Memory and Long-Term Memory.

Perception, working memory, and long-term memory each evoke neural responses in the visual cortex. While previous neuroimaging research on the role of the visual cortex in memory has largely emphasized similarities between perception and memory, we hypothesized that responses in the visual cortex would differ depending on the origins of the inputs. Using fMRI, we quantified spatial tuning in the visual cortex while participants (both sexes) viewed, maintained in working memory, or retrieved from long-term memory a peripheral target. In each condition, BOLD responses were spatially tuned and aligned with the target's polar angle in all measured visual field maps including V1. As expected given the increasing sizes of receptive fields, polar angle tuning during perception increased in width up the visual hierarchy from V1 to V2, V3, hV4, and beyond. In stark contrast, the tuned responses were broad across the visual hierarchy during long-term memory (replicating a prior result) and during working memory. This pattern is consistent with the idea that mnemonic responses in V1 stem from top-down sources, even when the stimulus was recently viewed and is held in working memory. Moreover, in long-term memory, trial-to-trial biases in these tuned responses (clockwise or counterclockwise of target) predicted matched biases in memory, suggesting that the reinstated cortical responses influence memory-guided behavior. We conclude that feedback widens spatial tuning in the visual cortex during memory, where earlier visual maps inherit broader tuning from later maps thereby impacting the precision of memory.