title: Stability of event-related (de-) synchronization during brain-computer interface-relevant mental tasks.
abstract: OBJECTIVE
  The aim of this study was to examine the temporal stability of event-related desynchronization/synchronization (ERD/S) patterns over several sessions as a function of mental task, frequency band, brain region and time interval during the imagery period.
  
  
  METHODS
  Nine volunteers participated in four sessions within 2 weeks of multi-channel EEG recordings. They performed seven mental tasks (i.e. mental rotation, word association, auditory imagery, mental subtraction, spatial navigation, imagery of familiar faces, motor imagery) during 7-s imagery periods. Cronbach's alpha coefficients were calculated over sessions to evaluate the stability of ERD/S values.
  
  
  RESULTS
  The word association, mental subtraction and spatial navigation task showed highest stability. Cronbach's alpha coefficients were highest in the alpha bands (7-10, 10-13 Hz), poorer in the beta bands (13-20, 20-30 Hz) and poorest in the theta band (4-7 Hz). In the majority of tasks, the first time interval and posterior left regions showed highest stability and strongest ERD in the alpha and beta bands.
  
  
  CONCLUSIONS
  Stability of ERD/S is strongly dependent on the specific task and differs between time intervals of the imagery period. Furthermore, stability was related to ERD in the alpha and beta bands.
  
  
  CONCLUSIONS
  The reliability of brain activation patterns is highly relevant for brain-computer interface developments.
authors: Department of Psychology, Neuropsychology, University of Graz, Universitätsplatz 2/III, 8010 Graz, Austria. elisabeth.friedrich@uni-graz.at
authors: Elisabeth V C
authors: EV
authors: Friedrich
authors: Reinhold
authors: R
authors: Scherer
authors: Christa
authors: C
authors: Neuper
mesh_terms: D000328:Adult; D000465:Algorithms; D062207:Brain-Computer Interfaces; D003627:Data Interpretation, Statistical; D004569:Electroencephalography; D005145:Face; D005260:Female; D006225:Hand / Q000502:physiology; D006801:Humans; D007092:Imagination / Q000502:physiology; D008433:Mathematics; D008606:Mental Processes / Q000502:physiology*; D009146:Music / Q000523:psychology; D009949:Orientation / Q000502:physiology; D015203:Reproducibility of Results; D014936:Word Association Tests; D055815:Young Adult