Functional properties of dorsolateral prefrontal cortical neurons in awake monkey.

Electrophysiological single-cell responses were studied in 134 neurons in Walker's areas 46 and 9 of the prefrontal cortex of two stumptail macaques. The neurons were systematically tested for various visual, auditory and somatosensory stimuli. In addition, the rate of neuronal discharges were observed in relation to provoked or spontaneous eye or limb movements. More than half (52.2%) of the neurons responded to stimulation, and the majority of them gave visual responses. Eighty percent of the visual neurons responded to the presentation of various objects, the remaining being selective for meaningful objects or the appearance and movements of the experimenter. Auditory, somatosensory, somatomotor and oculomotor responses were also encountered; 9.0% of the recorded neurons were multimodal. Despite the large stimulus repertoire 47.8% of the neurons were found to be only spontaneously active.