EEG in schizophrenic patients: mutual information analysis

Objective: The aim of the present study is to assess information transmission between different cortical areas in schizophrenics by estimating the average cross mutual information (A-CMI) and to characterize the dynamical property of the cortical areas of schizophrenic patients from multi-channel EEG by establishing the auto mutual information (AMI). Methods: We recorded the EEG from 16 electrodes in 10 schizophrenic patients and 10 age-matched normal controls. We estimated the slope of the AMI to evaluate the complexity of the EEG signal from one electrode and the A-CMI values of all 16×16 pairs of electrodes were calculated to investigate the information transmission of different cortical areas in schizophrenic patients. Results: In T5 and C3 electrodes, the schizophrenic patients had lower complexity than normal controls. The schizophrenic patients had significantly higher interhemispheric and intrahemispheric A-CMI values than the normal controls. Conclusions: These results are consistent with previous findings that suggest left hemispheric hypotemporality and inter- and/or intra-hemispheric overconnectivity in schizophrenics. Our results of the left hemispheric hypotemporality and the increased interhemispheric information transmission in temporal lobe may support the hypothesis that the abnormal laterlization in temporal lobe are due to left temporal lobe deficit in schizophrenic patients.