title: [Changes in EEG-complexity after subcortical ischemic brain damage].
abstract: BACKGROUND
  Complexity analysis of the EEG is a relatively new field in theoretical and clinical electrophysiology. The authors present results of EEG-analysis in a patient with stroke, utilizing the sensitivity of the new procedures with respect to linear and nonlinear synchronization.
  
  
  METHODS
  The EEG (19 channels) was recorded in a patient with subcortical unilateral ischaemic completed stroke involving the frontoparietal white matter while leaving the cortex intact and in 12 healthy controls in eyes open and in eyes closed conditions.
  
  
  RESULTS
  In the patient, increased Omega-complexity was found in slow (delta, theta) and lower alpha frequencies in the side of the stroke and in high frequencies (beta2 in eyes closed, alpha2, beta1 and beta2 in eyes open conditions) in the intact side. Synchronization likelihood was higher in the ischaemic side in the beta2 (eyes closed) and both in the beta1 and beta2 (eyes open) frequencies. Increasing Omega-complexity caused by eyes opening was markedly reduced in the patient in the beta frequencies compared to that seen in the controls. The difference was more conspicuous in the side of the infarct and involved not only the beta but also the alpha frequencies as well. Opening the eyes decreased synchronization likelihood in all frequency bands in the controls and also in the patient except the alpha2, beta1 and beta2 bands in the side of the lesion.
  
  
  CONCLUSIONS
  The increased Omega-complexity and decreased synchronization likelihood in the slow frequencies in the infarcted side is probably the result of lesioned interneuronal connections lowering the level of cooperation of neuronal systems involved in this type of activity. The increased Omega-complexity and decreased synchronization likelihood caused by eyes opening could not be observed in the beta and alpha frequencies in the side of the lesion, possibly caused by damaged thalamocortical connections.
authors.affiliation: Magyar Tudományos Akadémia, Pszichológiai Kutatóintézet, Budapest. molnar@cogpsyphy.hu
authors.forename: Márk
authors.initials: M
authors.lastname: Molnár
authors.forename: Roland
authors.initials: R
authors.lastname: Csuhaj
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Horváth
authors.forename: Ildikó
authors.initials: I
authors.lastname: Vastagh
authors.forename: Zsófia Anna
authors.initials: ZA
authors.lastname: Gaál
authors.forename: Balázs
authors.initials: B
authors.lastname: Czigler
authors.forename: Andrea
authors.initials: A
authors.lastname: Bálint
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Nagy
mesh_terms: D000513:Alpha Rhythm; D001611:Beta Rhythm; D002545:Brain Ischemia / Q000503:physiopathology*; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000503:physiopathology*; D003344:Cortical Synchronization; D003700:Delta Rhythm; D004569:Electroencephalography; D006801:Humans; D008297:Male; D008875:Middle Aged; D013826:Theta Rhythm