Involvement of the lateral prefrontal cortex in conditional suppression of gaze shift

Conditional execution and suppression of gaze shift are important in everyday life. To examine the possible involvement of the lateral prefrontal cortex (LPFC) in this process, we induced a local and reversible inactivation by injecting muscimol into 66 sites within the LPFC of monkeys and examined muscimol's effect on their performance in an oculomotor Go/No-Go task. This task required a subject to execute (Go) or suppress (No-Go) its gaze toward a target location in response to an instructional visual cue. Local injection of muscimol into 22 regions of the LPFC resulted in significant increases in the number of error saccades toward a few specific target locations during No-Go trials, whereas there were no error saccades in the Go trials. The onset latency of error saccades in No-Go trials was significantly longer than that of correct saccades in Go trials, but their velocity and amplitude were similar to those of correct saccades in Go trials. Go correct saccades appeared intact after the injections. These findings provide evidence that different regions of the LPFC are involved in the conditional suppression of gaze shift toward a few specific target locations, which may occur through a top-down suppressive mechanism.