Localization of function within the dorsolateral prefrontal cortex of the rhesus monkey.

Abstract Although lateral prefrontal lesions in the monkey are known to produce impairments on spatial delayed response and spatial delayed alternation, there is some question as to whether the delay, the spatial features, or a combination of the two is the critical factor in these tests giving rise to the impairments. Accordingly, the effects of several different lateral frontal lesions were compared on two spatial tasks, one which did involve intratrial delays (delayed alternation) and one which did not (a conditional position response test). The findings indicated the existence of two functionally distinct subdivisions of the dorsolateral prefrontal cortex: one in the principal sulcus, damage to which was responsible for impaired performance on the spatial task with delay; and the other in the arcuate sulcus, removal of which was responsible for impaired performance on the spatial task without delay. These findings together with those of other investigators suggest that the cortex in the principal sulcus may be concerned with a form of spatial memory, whereas the arcuate cortex is concerned with some other, as yet unspecified function.