Detection of non-linearity in schizophrenic patients using magnetoencephalography

The aim of this study is to investigate the presence of any non-linearity in the magnetoencephalographic recordings (MEG) from the temporal lobe of schizophrenic patients in comparison with controls, in order to find the differences underlying the brain waves. We calculated the correlation dimension, which is a measure of the complexity of the dynamic system, as well as the first Lyapunov exponent that indicates the system's unpredictability. The schizophrenic group consisted of 3 men and 7 women aged 23-32 years (mean 27.2, SD=3.5) and the control group of 3 men and 6 women aged 26-35 years (mean 31.6 +/- 4.1). There were no significant differences between the two groups as far as age and sex were concerned. None of them received any medication. The analysis of the MEG in the schizophrenic group showed lower dimension complexity and moreover the first Lyapunov exponent presented lower values compared with the corresponding ones in the control group, which means lower information processing. EEG findings as determined by MEG and non-linear analysis may offer important perspectives to better understand brain function in schizophrenia.