title: P1 amplitude across replicates: does measurement method make a difference?
abstract: OBJECTIVE
  Most cortical auditory evoked potentials instruments provide a "default" peak-to-baseline (P-B) amplitude and a means for obtaining a peak-to-trough (P-T) measure. This study investigated the sensitivity of these two measures in assessing the effects of repeated runs on the P1 component of the electrophysiological response.
  
  
  METHODS
  Cortical auditory evoked potentials were recorded on 30 normal hearing young adults. Three stimuli were used: an 80-millisecond synthetic /da/ and a 1 kHz tone burst of 40- and 80-millisecond durations. Stimuli were presented at 60 dB normal hearing level in a counterbalanced order. Three serial replicates were obtained for each stimulus. P1 amplitude and latency were measured.
  
  
  RESULTS
  The P-T amplitudes diminished significantly (P < 0.01) from replicate 1 to replicate 3 for each of the three stimulus types, but P-B amplitudes did not. P1 latency findings were consistent with effects shown by diminished P-T amplitude data in which latency increased significantly (P = 0.024) from replicate 1 to replicate 3 for one stimulus (40-millisecond tone).
  
  
  CONCLUSIONS
  The P-T amplitude measurement method identified significant decrements in amplitude because repeated runs were obtained, whereas the P-B method did not. These findings suggest that a P-T method is more sensitive to some P1 electrophysiological activity than is a P-B measure.
authors.affiliation: Department of Speech and Hearing Sciences, The University of Southern Mississippi, Hattiesburg, Mississippi 39406-0001, USA. charles.marx@usm.edu
authors.forename: Charles Gordon
authors.initials: CG
authors.lastname: Marx
authors.forename: Edward L
authors.initials: EL
authors.lastname: Goshorn
mesh_terms: D000328:Adult; D000465:Algorithms; D001303:Auditory Cortex / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004569:Electroencephalography / Q000379:methods*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult