Neurobiology of Smooth Pursuit Eye Movement Deficits in Schizophrenia: An fMRI Study

Abstract

Smooth pursuit eye movements are abnormal in patients with schizophrenia. The investigators used functional magnetic resonance imaging (fMRI) to compare brain hemodynamic response during a smooth pursuit eye movement task in patients with schizophrenia and healthy comparison subjects. Fourteen patients with schizophrenia and 14 healthy comparison subjects performed a smooth pursuit eye movement task while undergoing 1.5-T fMRI. Echo-planar images from the blocked design were evaluated with both a whole-brain random-effects analysis and a region-of-interest analysis. Smooth pursuit deficits were assessed outside the fMRI apparatus by using infrared oculography and were assessed during scanning by evaluating echo-planar time-series data from the eyes. Compared to the healthy subjects, the patients with schizophrenia exhibited greater activity in both posterior hippocampi and the right fusiform gyrus during smooth pursuit eye movements. The region-of-interest analysis revealed subtle activity deficits in frontal and occipital regions in the patients with schizophrenia. Smooth pursuit deficits in the subjects with schizophrenia included lower gain (eye velocity relative to target velocity) and a higher percentage of total eye movements due to anticipatory saccades, compared with the healthy subjects. The observed group differences are consistent with evidence for diminished inhibitory function in the hippocampus as well as for a disturbance in a frontotemporal network subserving smooth pursuit eye movements in schizophrenia.