Symmetry of callosal information transfer in schizophrenia: a preliminary study

Objective: While there is much evidence to suggest left hemisphere dysfunction and interhemispheric transfer deficits in schizophrenia, the right hemisphere is rarely implicated. This study uses 128-channel EEG to assess whether asymmetry of interhemispheric transfer found in normal individuals is present in those with schizophrenia, and whether this might point to a right-hemisphere dysfunction. Methods: Simple reaction time (RT) was recorded to stimuli presented to the left visual field (LVF), right visual field (RVF) or bilaterally (BVF) in 13 males with schizophrenia and 13 controls. 128-Channel EEG was simultaneously recorded. Interhemispheric transfer time (IHTT) in each direction was calculated by comparing the latencies of N160 EP components in the hemispheres contralateral and ipsilateral to stimulation. Results: While controls showed faster information transfer from the right-to-left hemisphere, this asymmetry was not present in the schizophrenia group who also exhibited a concomitant decrease in the amplitude of the N160 in the right hemisphere. Conclusions: Results are interpreted with reference to a loss of rapidly conducting myelinated axons in the right hemisphere in schizophrenia. (C) 2004 Elsevier B.V. All rights reserved.