Evidence for impaired visual prediction error in schizophrenia.

BACKGROUND: Mismatch negativity (MMN) is regarded a prediction error signal that is deficient in schizophrenia in the auditory modality. If, however, MMN reflects a general computational signal of the cortex, then MMN should be also deficient in the visual modality in schizophrenia patients.
METHODS: Twenty-two schizophrenia patients and 24 matched healthy controls finished a visual oddball task while high-density electroencephalogram was recorded. Visual mismatch negativity was computed as a surrogate marker of prediction error.
RESULTS: Visual MMN, as measured over posterior extra-striate cortical areas, was significantly reduced in schizophrenia at about 300 ms post stimulus. Standardized mean difference was -.98, corresponding to a large effect size.
CONCLUSIONS: A posterior visual MMN deficit in schizophrenia is demonstrated for the first time. Our results tentatively suggest a supra-modal MMN deficit in schizophrenia and thus argue in favor of reduced prediction error estimation in schizophrenia.