Effects of spontaneous eye movements on spatial memory in macaque periarcuate cortex.

Persistent activity in prefrontal cortex during delayed response tasks is a putative neural correlate of spatial working memory. We tested whether this activity was sensitive to eye movements made during the memory interval by recording from prefrontal neurons while monkeys performed a delayed spatial matching saccade task in which they were allowed to make eye movements freely. We found that eye movements degraded the spatial tuning of persistent activity even as there was an improvement in behavioral performance. Although the strength of the memory signal decreased, delay activity continued to signal the location of cue. The results suggest that free eye movements reduce neuronal gain rather than add variability. The saccades performed during the delay suggest the existence of a rehearsal mechanism that could contribute to working memory maintenance. The results do not provide support for a segregation of storage and executive functions in the periarcuate cortex.