Information Processing in the Primate Prefrontal Cortex

Abstract

Working memory is a mechanism for short-term active storage of information and for processing stored information. Working memory is an important concept to understand prefrontal cortical functions. Although evidences for temporary storage mechanisms of information have been accumulated, little is known about neuronal mechanisms for processing information. To understand how information is processed in the nervous system, we need to know what information single-neuron activity represents and how represented information by singleneuron activities changes along the temporal sequence of the trial. We used two kinds of oculomotor version of the delayedresponse (ODR) tasks and examined what information prefrontal single-neuron activity represents. We found that all cue-period activity represented cue positions and that most of delay-period activity represented cue positions. However, most of oculomotor activity represented saccade directions. These results suggest that prefrontal neurons participate in sensory-motor transformation. To examine prefrontal participation in sensory-motor transformation, we analyzed single-neuron activities using a population vector analysis. As a result, we found that information represented by a population of PFC neurons changes gradually during the delay period from information for visual cue to that for saccade.