Mnemonic and Predictive Functions of Cortical Neurons in a Memory Task

Single-neuron discharge was recorded from prefrontal and posterior parietal cortex in monkeys performing a visuo-motor memory task with temporal and spatial separation between cue (color) and directional manual response. During the delay interval between cue and response, neurons in both cortices engaged in two concurrent and reciprocal trends of discharge: (a) sensory-coupled, decelerating firing apparently related to color retention, or (b) motor-coupled, accelerating firing apparently related to the anticipated response direction. In both cortices, the acceleration of the direction-anticipating activity was related to the probability with which the animal could predict, and prepare for, the correct response site. Our findings suggest that neurons from prefrontal and parietal cortex are part of distributed networks, with representational and operational properties, for visuomotor cognitive processing.