Neurons in monkey prefrontal cortex that track past or predict future performance

Although frontal cortex is thought to be important in controlling behavior across Long periods of time, most studies of this area concentrate on neuro nal responses instantaneously relevant to the current task. In order to inv estigate the relationship of frontal activity to behavior over Longer time periods, we trained rhesus monkeys on a difficult oculomotor task. Their pe rformance fluctuated during the day, and the activity of prefrontal neurons , even measured while the monkeys waited for the targets to appear at the b eginning of each set of trials, correlated with performance in a probabilis tic rather than a determinist manner: neurons reflected past or predicted f uture performance, much more than they reflected current performance. We su ggest that this activity is related to processes such as arousal or motivat ion that set the tone for behavior rather than controlling it on a millisec ond basis, and could result from ascending pathways that utilize slow, seco nd-messenger synaptic processes.