Smooth pursuit eye movement and directional motion contrast sensitivity in schizophrenia

Walter L. Slaghuis, University of Tasmania
Alison C. Bowling, Southern Cross University
Rebecca V. French, University of Tasmania

Abstract

Although the occurrence of visual processing and eye-movement disorders in schizophrenia have been widely recognized, their relationship with the symptoms of schizophrenia is less well understood. In two experiments the relationship between directional-motion processing and smooth-pursuit eye movement was investigated in normal observers and in groups with positive and negative symptoms in schizophrenia. The first experiment measured linear smooth-pursuit eye movement at six target velocities from 5.0 to 30.0 degrees and the second experiment measured directional motion-contrast sensitivity at three spatial (1.0, 4.0 and 8.0 c/deg) and five temporal (0.75, 3.0, 6.0, 12.0 and 18.0 Hz) frequencies in the same groups of observers. No significant differences were found between the control and positive-symptom group in directional motion-contrast sensitivity and smooth-pursuit eye movements. In comparison, a relationship was found between a significant reduction in directional motion-contrast sensitivity and significantly reduced smooth-pursuit eye movement in the negative-symptom group and serves to further cleave the distinction between positive and negative symptoms in schizophrenia. The relationship between visual motion processing and pursuit eye movement in the negative-symptom group was explained by a disorder in directional motion processing that fails to fully engage the pursuit eye movement system and reduces smooth pursuit eye-velocity gain.