Korean J Psychopharmacol.  1998 Apr;9(1):67-72.

Nonlinear Dynamic Analysis Using Lyapunov Exponent of EEG in Patients with Schizophrenia

• Kim DJ
• Pae CU
• Jeong J
• Chae JH
• Kim SY
• Go HJ
• Paik IH

Abstract

OBJECT: It seemed worthwhile to estimate nonlinear measures of the electroencephalogram (EEG) in schizophrenic patients, because nonlinear measures might serve as indicators of the specific brain function in schizophrenia. METHOD: Previous studies which estimated the chaoticity in the brain of schizophrenia with nonlinear methods recorded the EEGs at limited electrodes, so we tried to record EEGs from 16 channels for nonlinear analysis in 19 patients with Schizophrenia and 8 healthy control subjects. We employed a new method to calculate the nonlinear invariant measures. For limited noisy data, this algorithm was strikingly faster and more accurate than previous ones.
RESULTS
Our results showed that the schizophrenic patients had lower values of the largest positive Lyapunov exponent at the left inferior frontal and anterior temporal head regions compared with normal controls.
CONCLUSIONS
These results suggest that the nonlinear analysis of the EEGs such as the estimation of the largest positive Lyapunov exponent seems to be a useful tool in analyzing EEG data to explore the neurodynamics of the brain of schizophrenic patients.

Keyword

Schizophrenia; Chaos; EEG; Nonlinear dynamics; Lyapunov exponent

MeSH Terms

Brain
Electrodes
Electroencephalography*
Head
Humans
Nonlinear Dynamics*
Schizophrenia*