title: Evoked gamma oscillations in human scalp EEG are test-retest reliable.
abstract: OBJECTIVE
  Evoked, phase-locked gamma oscillations of the electroencephalogram (EEG) have been demonstrated to be modulated by both bottom-up as well as top-down factors. However, to date the test-retest reliability of these oscillations has not been studied systematically.
  
  
  METHODS
  We recorded EEG activity of 12 healthy volunteers in response to stimuli of different sizes. Each participant took part in two sessions separated by two weeks in time. To obtain an estimate of the reliability of evoked gamma band responses (GBRs), we compared frequency and magnitude of phase-locked EEG oscillations between sessions.
  
  
  RESULTS
  In response to large stimuli magnitude and frequency of the evoked GBR yielded significant reliability. However, this was not the case for stimuli which were too small to evoke detectable GBRs.
  
  
  CONCLUSIONS
  The results are in accordance with studies demonstrating a dependence of gamma oscillations on stimulus parameters.
  
  
  CONCLUSIONS
  The current findings suggest that using appropriate stimulation, the evoked gamma response has sufficient test-retest reliability for use in assessing clinical changes in neurophysiological status.
authors.affiliation: Institute of Psychology, Department of Biological Psychology, Otto-von-Guericke University, Magdeburg, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Fründ
authors.forename: Jeanette
authors.initials: J
authors.lastname: Schadow
authors.forename: Niko A
authors.initials: NA
authors.lastname: Busch
authors.forename: Ursula
authors.initials: U
authors.lastname: Körner
authors.forename: Christoph S
authors.initials: CS
authors.lastname: Herrmann
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology; D010507:Periodicity; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D015203:Reproducibility of Results; D012535:Scalp / Q000502:physiology*; D012858:Size Perception / Q000502:physiology*; D013997:Time Factors