DIFFERENCES IN CEREBRAL ACTIVATION DURING SMOOTH-PURSUIT AND SACCADICEYE-MOVEMENTS USING POSITRON-EMISSION-TOMOGRAPHY

Background: Abnormalities of smooth pursuit eye movements occur common ly in schizophrenia, but the pathophysiological significance of these abnormalities is unknown. To address this, the authors conducted a pil ot study in which we examined differences in regional cerebral activat ion using positron-emission tomography (PET) in normal volunteers as t hey performed two types of eye movements. Methods: Cerebral activation in 10 normal volunteers was studied using (CO2)-O-15 PET while subjec ts tracked a visual target using smooth pursuit and saccadic eye movem ents. A left-hand movement comparison task provided a physiologic land mark for verification of the location of the frontal eye fields (FEFs) . Results: Subjects exhibited FEF activation during both smooth pursui t and saccadic eye movements, which was greater in the latter. During smooth pursuit, subjects also exhibited increased cerebral activation in the left temporal-occipital border and left superior frontal cortex and decreased activation in medial superior parietal and insular regi ons relative to saccades. Other cortical visual and eye-movement brain regions also demonstrated differences in activation between the two v isual tasks. Conclusions: Significant fEF activation appears to underl ie both smooth pursuit and saccadic eye movements but may be more crit ical in the former. Dysfunction of the frontal lobe, and possibly of o ther areas in the pursuit pathway such as the temporo-occipital motion area, may contribute to observed eye-movement abnormalities in patien ts with schizophrenia. Biol Psychiatry 1998;44: 685-689 (C) 1998 Socie ty of Biological Psychiatry.