Abnormal functional asymmetry in occipital areas may prevent frontotemporal regions from achieving functional laterality during the WCST performance in patients with schizophrenia.

There is much evidence of frontotemporal lateralized abnormalities in schizophrenia. However, the relationship has not yet been examined between performance on the Wisconsin Card Sorting Test, with supposed anterior left dominance and event-related potential (ERP) asymmetry. ERPs recorded at homologous bilateral sites were compared using statistical permutation methods. Patients had an unexpected abnormal lateralization over occipital regions, preceding slow anterior potentials. This indicates a defect in early stages of information processing, which may contribute to prevent further hemispheric lateralization during performance.