Interhemispheric EEG coherence is reduced in auditory cortical regions in schizophrenia patients with auditory hallucinations

Abstract

Central auditory processing has been reported to be impaired in schizophrenia patientswho experience auditory

hallucinations, and interhemispheric transfer in auditory circuits may be compromised. In this study, we used

EEG spectral coherence to examine interhemispheric connectivity between cortical areas known to be important

in the processing of auditory information. Coherence was compared across three subject groups: schizophrenia

patients with a recent history of auditory hallucinations (AH), schizophrenia patientswho did not experience auditory

hallucinations (nonAH), and healthy controls (HC). Subjects listened to pure tone and word stimuli while

EEG was recorded continuously. Upper alpha and upper beta band coherence was calculated from six pairs of

electrodes located over homologous auditory areas in the left and right cerebral hemispheres. Significant

between-group differences were found on four electrode pairs (C3–C4, C5–C6, Ft7–Ft8 and Cp5–Cp6) in the

upper alpha band. Relative to both the HC and nonAH groups, coherence was lower in the AH patients, consistent

with the hypothesis that interhemispheric connectivity is reduced in these patients.