CONTRAST SENSITIVITY FOR STATIONARY AND DRIFTING SPATIAL-FREQUENCY GRATINGS IN POSITIVE-SYMPTOM AND NEGATIVE-SYMPTOM SCHIZOPHRENIA

To investigate the transient channel deficit hypothesis in schizophren ia, the authors measured the contrast sensitivity for stationary and d rifting gratings in groups with positive-and negative-symptom schizoph renia. The negative-symptom group showed a significant reduction in co ntrast sensitivity for stationary and drifting gratings at low, medium , and high spatial frequencies in comparison to the control group. The re were no differences in contrast sensitivity between the control and positive-symptom groups for stationary and drifting gratings at low-s patial frequencies, but there were significant reductions at medium an d high spatial frequencies. The results are consistent with a disorder in both sustained and transient channels in negative-symptom schizoph renia and a disorder in sustained channels in positive-symptom schizop hrenia.