title: Reliability of early cortical auditory gamma-band responses.
abstract: OBJECTIVE
  To evaluate the test-retest reliability of event-related power changes in the 30-150 Hz gamma frequency range occurring in the first 150 ms after presentation of an auditory stimulus.
  
  
  METHODS
  Repeat intracranial electrocorticographic (ECoG) recordings were performed with 12 epilepsy patients, at ≥1-day intervals, using a passive odd-ball paradigm with steady-state tones. Time-frequency matching pursuit analysis was used to quantify changes in gamma-band power relative to pre-stimulus baseline. Test-retest reliability was estimated based on within-subject comparisons (paired t-test, McNemar's test) and correlations (Spearman rank correlations, intra-class correlations) across sessions, adjusting for within-session variability. Reliability estimates of gamma-band response robustness, spatial concordance, and reproducibility were compared with corresponding measurements from concurrent auditory evoked N1 responses.
  
  
  RESULTS
  All patients showed increases in gamma-band power, 50-120 ms post-stimulus onset, that were highly robust across recordings, comparable to the evoked N1 responses. Gamma-band responses occurred regardless of patients' performance on behavioral tests of auditory processing, medication changes, seizure focus, or duration of test-retest interval. Test-retest reproducibility was greatest for the timing of peak power changes in the high-gamma range (65-150 Hz). Reliability of low-gamma responses and evoked N1 responses improved at higher signal-to-noise levels.
  
  
  CONCLUSIONS
  Early cortical auditory gamma-band responses are robust, spatially concordant, and reproducible over time.
  
  
  CONCLUSIONS
  These test-retest ECoG results confirm the reliability of auditory gamma-band responses, supporting their utility as objective measures of cortical processing in clinical and research studies.
authors: Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
authors: Mackenzie C
authors: MC
authors: Cervenka
authors: Piotr J
authors: PJ
authors: Franaszczuk
authors: Nathan E
authors: NE
authors: Crone
authors: Bo
authors: B
authors: Hong
authors: Brian S
authors: BS
authors: Caffo
authors: Paras
authors: P
authors: Bhatt
authors: Frederick A
authors: FA
authors: Lenz
authors: Dana
authors: D
authors: Boatman-Reich
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001303:Auditory Cortex / Q000502:physiology*; D003399:Craniotomy; D004567:Electrodes, Implanted; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012640:Seizures / Q000503:physiopathology; D013067:Speech Perception / Q000502:physiology; D055815:Young Adult