Abstract
In primates, the Frontal Eye Field (FEF) controls saccades used to search the environment and foveate search targets. The receptive fields (RFs) of FEF neurons are not always statically fixed to a retinotopic location. Rather, they predictively remap to conform to the future fixation position just before a saccade begins. Two modes of perisaccadic remapping have been observed. In forward remapping, the RF jump follows a vector parallel to the upcoming saccade. In convergent remapping, the RF is pulled toward the endpoint of the upcoming saccade. Here, we ask what adaptive purpose RF remapping may serve for visual search behavior, characterized by exploratory and exploitative saccades. Exploratory saccades are high latency, low velocity saccades performed in a sequence to gather visual information, while exploitative saccades are low latency, high velocity, individual saccades performed to foveate the search target. We hypothesize that forward remapping is adaptive for exploratory saccades because it allows for a retinotopically accurate preview that will facilitate potential discovery of targets and planning of upcoming movements. Likewise, we hypothesize that convergent remapping occurs during exploitative saccades, and that this momentarily enhances visual representation around the target. To test this, we recorded from FEF neurons while monkeys searched for a target (gabor patch) embedded in a Perlin noise background. The monkeys were trained to ignore visual probes that were rapidly flashed at random locations during the search behavior. The visual responses elicited by the probes allowed us to infer RF location continuously throughout natural search behavior. We observed forward remapping around exploratory saccades and convergent remapping around exploitative saccades. This effect was strongest in cells that showed delay period activity during a memory guided saccade task. These results suggest that the dynamic reshaping of visual space in FEF facilitates different saccadic strategies.
Meeting abstract presented at VSS 2018