Abstract
The entorhinal cortex (EC) is critical to the formation of memories for complex visual relationships. Thus we might expect that EC neurons encode visual scenes within a consistent spatial framework to facilitate associations between items and the places where they are encountered. In particular, encoding of visual borders could provide a means to anchor visual scene information in allocentric coordinates. Studies of the rodent EC have revealed neurons that represent location, heading, and borders when an animal is exploring an environment. Because of interspecies differences in vision and exploratory behavior, we reasoned that the primate EC may represent visual space in a manner analogous to the rodent EC, but without requiring physical visits to particular places or items. We recorded activity of EC neurons in non-human primates (Macaca mulatta) that were head-fixed and freely viewing novel photographs presented in a fixed external reference frame. We identified visual border cells, neurons that had increased firing rate when gaze was close to one or more image borders. Border cells were co-localized with neurons that represented visual space in a grid-like manner and with neurons that encoded the angular direction of saccadic eye movements. As a population, primate EC neurons appear to represent gaze location, gaze movement direction, and scene boundaries. These spatial representations were detected in the presence of changing visual content, suggesting that the EC provides a consistent spatial framework for encoding visual experiences.
Meeting abstract presented at VSS 2016