Estimation of nonlinear measures of schizophrenia patients' EEG in emotional states

The emotional dysfunction has been reported as a clinical symptom of the disorder in some studies of schizophrenia patients. To study the underlying brain dynamics during emotional states in schizophrenia patients by nonlinear analysis, the EEG signals can be investigated. The aim of this study was to estimate nonlinearity of schizophrenics' EEG, using the correlation dimension (D2) and the largest Lyapunov exponent (L1), at rest and while listening auditory stimuli with emotional content. EEG data were recorded under two conditions as resting-period and auditory stimulation periods (white noise (WN) and classical Turkish music (CTM)) during 8 min from schizophrenia patients and age-matched healthy controls. We found that the patients had significantly lower values of L1 at the left frontal, parietal and right central regions during whole procedure compared with controls and had a significantly higher D2 only in the F3 and the P4 regions during the CTM exposure. However, no significant L1 and D2 differences were found between periods for WN and CTM in schizophrenics. It can be concluded that schizophrenic brain has less flexible neural-networks in the left fronto-temporal area. The chaotic analysis may be a useful tool in analyzing the EEG to investigate the neurodynamics of the schizophrenia patients' brain during emotional stimuli. (C) 2015 Elsevier Masson SAS. All rights reserved