Abstract
A number of previous studies have investigated the response properties of prefrontal (PFC) neurons during conditional visuomotor tasks in which a monkey is required to perform one response (for example, a rightward saccade) following presentation of one stimulus, and a different response following presentation of another (for example, a leftward saccade). These tasks typically require the animal to perform the same general behaviour (a saccade), but modify the direction of their response depending upon the behavioural rule indicated by the stimulus. Real-world situations, however, often require that an individual be able to flexibly choose between different behavioural alternatives depending upon the contingencies dictated by the environment. Here we recorded from 159 neurons in the left lateral PFC of one monkey during a delayed-match-to-sample task and a conditional visuomotor task in which the animal was required to perform one of two behaviors depending upon which of four visual stimuli was presented. In this task, the monkey was rewarded for performing a pro-saccade following presentation of two stimuli, and an anti-saccade following presentation of the other two. Results of two-way ANOVAs evaluated at p<.01 revealed that many of these PFC cells showed task-related differences in activity during cue (53/159= 33.3%), and delay (60/159= 37.7%) epochs. Fewer cells showed stimulus-related activity differences during these time periods (13/159= 8.18%, and 11/159= 6.91%, respectively). An interaction between task and stimulus was found in only a small number of cells (2/159= 1.26% and 6/159= 3.77%). These findings demonstrate modulations of cue and delay-related activity in PFC neurons by behavioural rules.
Supported by: Canadian Institutes of Health Research and the EJLB Foundation