Abstract
We examine delay period activity in the FEF during the performance of an object-based working memory task. In the task, the monkey is briefly presented a single image (sample) in the periphery. Following the sample presentation, the monkey must remember the sample throughout a 1-second blank delay period. Following the delay, one target (a repeat of the sample image) and one distractor object appear in the periphery and the monkey must saccade to the matching target to receive a reward. We compare FEF neuronal activity during blocks in which target and distractor images always appear at locations that include the sample location (overlapping condition) with blocks in which the target/distractor always appear at positions rotated 90 degrees from the sample position (orthogonal condition). Thus we can examine the degree to which spatially selective delay period activity of FEF neurons contributes to object-based working memory. We also use a memory-guided saccade task to identify the functional classes of FEF neurons that might contribute to the persistence of purely object-based information. We observe persistent, spatially selective delay period activity in the FEF consistent with the use of spatial signals in maintaining object information.
NIH grant EY014924, NSF grant IOB-0546891, and the McKnight Foundation.