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.