title: Long-term stability and consistency of EEG event-related (de-)synchronization across different cognitive tasks.
abstract: OBJECTIVE
  We examined whether task-related band power changes (event-related desynchronization/synchronization; ERD/ERS) that have been linked to individual differences in cognitive ability demonstrate satisfying temporal stability and cross-situational consistency.
  
  
  METHODS
  Multi-channel EEG recordings from 29 adults, assessed at three different occasions over 2 years were examined. Between-session correlations and consistency coefficients (Cronbach's alpha) across the three experiments were evaluated for both, spectral power features of the resting EEG and ERD/ERS estimates while the participants performed some cognitive task (i.e. different elementary cognitive tasks that put comparable demands on the participants).
  
  
  RESULTS
  ERD/ERS values, while subjects performed a cognitive task, demonstrated satisfactory stability and consistency (i.e. >0.7), whereby the degree of consistency varied as a function of frequency band and brain region. Highest consistency was found for the 8-10 Hz ERD in parieto-occipital recording sites (i.e. >0.9). In resting EEG, mean alpha (gravity) frequency was the most stable EEG feature.
  
  
  CONCLUSIONS
  The present data suggest that ERD/ERS phenomena in different narrow frequency bands are rather stable over time and across different situations. The relatively high reproducibility of ERD/ERS promotes the usefulness of this measure in assessing individual differences of physiological activation patterns accompanying cognitive performance.
  
  
  CONCLUSIONS
  This study addresses the issue of reproducibility of EEG in general and ERD/ERS experiments in particular, which is a prerequisite for both basic research and clinical studies.
authors.affiliation: Institute of Psychology, University of Graz, Universitaetsplatz 2/III, A-8010 Graz, Austria. christa.neuper@uni-graz.at
authors.forename: Christa
authors.initials: C
authors.lastname: Neuper
authors.forename: Roland H
authors.initials: RH
authors.lastname: Grabner
authors.forename: Andreas
authors.initials: A
authors.lastname: Fink
authors.forename: Aljoscha C
authors.initials: AC
authors.lastname: Neubauer
mesh_terms: D000293:Adolescent; D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D003344:Cortical Synchronization; D004569:Electroencephalography / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013995:Time