Effect of expected reward magnitude on the response of neurons in the dorsolateral prefrontal cortex of the macaque

The dorsolateral prefrontal cortex plays a critical role in guiding actions that ensue seconds after an instruction. We recorded from neurons in area 46 and the frontal eye field (FEF) while monkeys performed a memory-guided eye movement task. A visual cue signaled whether a small or large liquid re ward would accompany a correct response. Many neurons in area 46 responded more when the monkey expected a larger reward. Reward-related enhancement w as evident throughout the memory period and was most pronounced when the re membered target appeared in the neuron's response field. Enhancement was no t present in the FEF. The mixture of neural signals representing spatial wo rking memory and reward expectation appears to be a distinct feature of are a 46.