Contrast sensitivity for stationary and drifting spatial frequency gratings in positive- and negative-symptom schizophrenia.

To investigate the transient channel deficit hypothesis in schizophrenia, the authors measured the contrast sensitivity for stationary and drifting gratings in groups with positive- and negative-symptom schizophrenia. The negative-symptom group showed a significant reduction in contrast sensitivity for stationary and drifting gratings at low, medium, and high spatial frequencies in comparison to the control group. There were no differences in contrast sensitivity between the control and positive-symptom groups for stationary and drifting gratings at low-spatial frequencies, but there were significant reductions at medium and high spatial frequencies. The results are consistent with a disorder in both sustained and transient channels in negative-symptom schizophrenia and a disorder in sustained channels in positive-symptom schizophrenia.