Abstract
Working memory (WM) enables information storage for future use, bridging the gap between perception and behavior. We hypothesize that WM representations are abstractions of low-level perceptual features. Yet the neural nature of these putative abstract representations has thus far remained impenetrable. Here, we first demonstrate that distinct visual stimuli (orientated gratings and moving dots) are flexibly re-coded into the same WM format in visual and parietal cortex when that representation is useful for memory-guided behavior. Next, we aimed to reveal the latent nature of the abstract WM representation. We predicted that the spatial distribution of higher response amplitudes across a topographic map forms a line at a given angle, as if the retinal positions constituting a line were actually visually stimulated. To test this, we reconstructed the spatial profile of neural activity during WM by projecting the amplitudes of voxel activity during the delay period for each orientation and direction condition into visual field space using parameters obtained from models of each visual map’s population receptive field. Remarkably, the visualization technique unveiled a stripe encoded in the amplitudes of voxel activity at an angle matching the remembered feature in many of the visual maps. Finally, we used models of V1 that demonstrate the feasibility of such a working memory mechanism and ruled out potential confounds. We conclude that mnemonic representations in visual cortex are abstractions of percepts that are more efficient than and proximal to the behaviors they guide.