Detection of non-linearity in the EEG of schizophrenic patients

Ying Jie Lee, Yi Sheng Zhu, Yu Hong Xu, Min Fen Shen, Hong Xuan Zhang, N. V. Thakor

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


Objective: The aim of this study is to detect non-linearity in the EEG of schizophrenia with a modified method of surrogate data. We also want to identify if dimension complexity (correlation dimension using spatial embedding) could be used as a discriminating statistic to demonstrate non-linearity in the EEG. The difference between the attractor dimension of healthy subjects and schizophrenic subjects is expected to be interpreted as reflecting some mechanisms underlying brain wave by views of non-linear dynamics analysis may reflect mechanistic differences. Methods: EEGs were recorded with 14 electrodes in 18 healthy male subjects (average age: 26.3; range: 20-35) and 18 male schizophrenic patients (average age: 30.6; range: 24-40) during a resting eye-closed state. Neither of two groups was taking medicines. All artificial epochs in the EEG records were rejected by an experienced doctor's visual inspection. Results: Testing non-linearity with modified surrogate data, we showed that correlation dimension of EEG data of schizophrenia does refuse the null hypothesis that the data were resulted from a linear dynamic system. A decrease of dimension complexity was found in the EEG of schizophrenia compared with controls. We interpreted it as the result of the psychopath's dysfunction overall brain. The surrogating procedure results in a significant increase in Ds. Conclusions: Non-linearity of the EEG in schizophrenia was proven in our study. We think the correlation dimension with spatial embedding as a good discriminating statistic for testing such non-linearity. Moreover, schizophrenic patients' EEGs were compared with controls and a lower dimension complexity was found. The results of our study indicate the possibility of using the methods of non-linear time series analysis to identify the EEGs of schizophrenic patients.

Original languageEnglish (US)
Pages (from-to)1288-1294
Number of pages7
JournalClinical Neurophysiology
Issue number7
StatePublished - 2001


  • Dimension complexity
  • EEG
  • Embedding methods
  • Non-linearity
  • Schizophrenia
  • Surrogate data

ASJC Scopus subject areas

  • Sensory Systems
  • Neurology
  • Clinical Neurology
  • Physiology (medical)


Dive into the research topics of 'Detection of non-linearity in the EEG of schizophrenic patients'. Together they form a unique fingerprint.

Cite this