title: Investigation of non-linear properties of multichannel EEG in the early stages of Parkinson's disease.
abstract: OBJECTIVE
  Modifications of brain activity in the early stages of Parkinson's disease (PD) are difficult to detect using electroencephalography (EEG) signals and are often biased by L-DOPA treatment. We compare here the performances of both linear and non-linear methods in differentiating EEG of L-DOPA naive PD patients from that of control subjects.
  
  
  METHODS
  Resting multichannel EEG (20 electrodes, 30 s epochs) of 9 patients with PD in Hoehn and Yahr stages 1-2 (4 women, 5 men, mean age 54.3 years, range 48-63 years) were compared with those of 9 control subjects (7 women, two men, mean age 51.3 years, range 43-61 years). The following measurements were computed: theta-, alpha- and beta-band relative powers constituted the linear indices; localized entropy, slope asymmetry and number of non-linear EEG segments constituted the non-linear indices.
  
  
  RESULTS
  In the case of linear quantification, only a decrease in the beta-band was observed for patients. Significant non-linear structures were observed in our EEG data. Non-linear quantifiers demonstrate an increase in entropy and in the number of non-linear EEG segments for the patients.
  
  
  CONCLUSIONS
  Changes in EEG dynamics observed here in L-DOPA naive PD patients may represent early signs of cortical dysfunction produced by subcortical dopamine depletion.
authors.affiliation: Laboratoire de Neurosciences Comportementales, Université René Descartes, 45 rue des Saints-Pères, F-75270 Cedex 06, Paris, France.
authors.forename: L
authors.initials: L
authors.lastname: Pezard
authors.forename: R
authors.initials: R
authors.lastname: Jech
authors.forename: E
authors.initials: E
authors.lastname: Růzicka
mesh_terms: D000465:Algorithms; D000978:Antiparkinson Agents / Q000627:therapeutic use; D004569:Electroencephalography; D019277:Entropy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D010300:Parkinson Disease / Q000188:drug therapy / Q000503:physiopathology* / Q000523:psychology; D011569:Psychiatric Status Rating Scales
chemical_list: D000978:Antiparkinson Agents