The prefrontal substrate of reflexive saccade inhibition in humans

Background: Prefrontal dysfunction in neuropsychiatric disorders such as schizophrenia has been shown to impair inbibition of reflexive saccadic eye movements; however it is unclear whether reflexive saccade inbibition can be attributed to a distinct subregion of the human prefrontal cortex. Methods: We tested 15 patients with acute unilateral ischemic lesions of the prefrontal cortex and 20 control sublects with an antisaccade task. Lesions were reconstructed using Talairach coordinates, and possible candidate regions for reflexive saccade inbibition were identified. Results: Significantly increased antisaccade error rates were observed in patients with lesions affecting a region in mid-dorsolateral prefrontal cortex or the white matter between this region and the anterior portions of the internal capsule. Antisaccade error rates of patients wilb lesions outside thisregion were normal, these findings were largely independent of lesion volume, postlesion delay, and subject age. Conclusions: Our findings suggest that inbibition of reflexive saccades depends on a circumscribed subregion of the human dorsolateral prefrontal cortex. This region closely corresponds to Brodmann area 46 as defined by recent cytoarchitectonic studies. Increased antisaccade error rates in patients with prefrontal pathology may be explained by dysfunction of this region.