Cortical activation pattern during saccadic eye movements in humans: localization by focal cerebral blood flow increases.

Regional cerebral blood flow (rCBF) was measured in human subjects during saccadic eye movements by a 254-channel dynamic gamma camera. Focal rCBF increases were repeatedly observed in an area within the middle precentral and premotor regions which corresponds to the frontal eye field in humans. Our findings suggest that this region is localized between the "face" and "hand" areas in the precentral gyrus and extends anteriorly out of the primary motor strip into the adjacent premotor zone. In addition, saccades were associated with focal blood flow increases in regions corresponding to the frontal supplementary motor area and to the posterior temporooccipital visual association cortex. Similar changes in patterns of rCBF occurred during contralateral and ipsilateral horizontal saccades and also during vertical saccades, and did not differ between the right and left hemispheres. Focal rCBF increases were observed in the frontal eye field during several additional test procedures including ocular fixation and visual perception of a nonmoving target, auditory stimulation with closed eyes, and reading. It is presumed that these focal flow increases reflect increased localized neuronal activity and metabolic rate and therefore permit visualization of the cortical activation pattern associated with saccadic eye movements in humans.