Schizophrenia and communication between the hemispheres

Barnett, K. J., Kirk, I. J., and Corballis, M. C.
Research Centre for Cognitive Neuroscience, Auckland University, New Zealand

EEG differences are often reported in schizophrenia research, with reductions of P2/P3 amplitudes, hemispheric topographic deviations, laterality differences, and abnormalities of ERPs obtained from linguistic stimuli most commonly cited. Recent research suggests that individuals with schizophrenia have a deficit in the transfer of verbal information from the right to the left hemisphere (Endrass et al., 2002). We used a basic visuospatial task to assess information transfer in individuals with schizophrenia (n=10) and age matched controls (n = 10) using the evoked potentials (EPs) method. EEG was recorded from 128 electrodes while participants underwent 200 trials in which they were required to make a recognition response to the presentation of a basic stimulus (a circle) which appeared briefly in either the left visual field (LVF), right visual field (RVF), or bilaterally (BVF). Interhemispheric transfer time was assessed using the N1-latency difference between the hemispheres ipsilateral and contralateral to stimulation. The schizophrenia group were characterised by differences in both functional laterality and information transfer between the hemispheres. The results will be discussed with reference to symptoms characteristic of schizophrenia and the role of the corpus callosum in information transfer.