Attentional modulation of perceptual organisation in schizophrenia.

INTRODUCTION

Previous studies indicated impaired perceptual organisation in schizophrenia. This study investigated lateral connection and attentional modulation in early visual cortex of schizophrenia patients.

METHODS

Contrast threshold was measured for a central Gabor patch, flanked with orthogonal and collinear Gabor patches. In the attended condition, participants performed a concurrent vernier task by determining the spatial offset of the flankers.

RESULTS

The controls (n=25) had lower contrast thresholds in the collinear condition than in the orthogonal condition, whereas the schizophrenia patients (n=43) did not benefit from the presence of collinear flankers. This deficit was not ameliorated by attentional modulation. Antipsychotic medication did not affect the performance.

CONCLUSIONS

These results suggest that lateral connections are impaired in early visual cortex of schizophrenia patients. This deficit cannot be restored by top-down attentional modulation of target-flanker interactions.