Forward and convergent remapping of receptive fields from local field potentials in frontal eye fields.

Receptive-field (RF) remapping, produced by attention and corollary discharges (CDs) of saccade commands, has been found in many brain areas. Most remapping studies use neurons' firing rates of spikes to determine their RFs, and relatively less is known about the remapping behavior of RFs derived from local field potentials (LFPs) which include contributions of synaptic inputs. Here we use LFPs to measure RF remapping in frontal eye fields (FEF) of macaques while they perform a delayed saccade task. We focus on the high-gamma and alpha bands of the LFPs because RFs from these bands show reliable remapping. We find that during the delay period, the high-gamma RFs shift towards the initial fixation point. During the perisaccadic period, the high-gamma RFs first shift towards the target (convergent remapping), then towards the post-saccadic RF locations (forward remapping), and finally towards the target again. These results are consistent with those of the firing-rate-defined RFs, with presumably attention-driven convergent remapping and CD-driven forward remapping occurring at different times. In contrast, the alpha RFs show no significant remapping in the delay period and only forward remapping throughout the perisaccadic period. To the extent that the high-gamma and alpha bands of LFPs may reflect synaptic inputs from local circuits and other brain areas, respectively, these results suggest that attentional remapping may be generated locally in FEF whereas forward remapping may have both local and distant contributions.