title: The time course of the amplitude and latency in the auditory late response evoked by repeated tone bursts.
abstract: BACKGROUND
  This study provides a detailed description of the time course of amplitude and latency in the auditory late response (ALR) elicited by repeated tone bursts.
  
  
  METHODS
  Tone bursts (50 and 80 dB SPL) were presented via insert earphones in trains of ten with interstimulus intervals (ISIs) of 0.7 and 2 msec and an intertrain interval of 15 sec. Averages were derived independently for each tone burst within the train across the total number of train presentations.
  
  
  METHODS
  Participants were 14 normal-hearing young adults.
  
  
  METHODS
  Data were analyzed in terms of the amplitudes and latencies of the N1 and P2 waves of the ALR as well as the N1-P2 amplitude.
  
  
  RESULTS
  The N1-P2 amplitude was a more stable measure than the amplitude of individual N1 and P2 peaks. The N1-P2 amplitude was maximal for the first tone burst and decreased in a nonmonotonic pattern for the remainder of the tone bursts within a stimulus train. The amplitude decrement was dependent on stimulus intensity and ISI. The latencies of N1 and P2 were maximal for the first tone burst and reduced approximately 20% for the rest of the stimuli in a train. The time course of N1 and P2 latencies was not dependent on stimulus intensity and ISI.
  
  
  CONCLUSIONS
  The reduction of latency in the time course of the ALR might be related to the fact that neurons with shorter latencies had faster recovery speed from adaptation and/or refractoriness than those with longer latencies. This finding is meaningful in the context of future research to restore normal adaptation in abnormal hearing populations such as cochlear implant patients.
authors.affiliation: Department of Communication Sciences and Disorders, University of Cincinnati, OH, USA. Fawen.Zhang@uc.edu
authors.forename: Fawen
authors.initials: F
authors.lastname: Zhang
authors.forename: James
authors.initials: J
authors.lastname: Eliassen
authors.forename: Jill
authors.initials: J
authors.lastname: Anderson
authors.forename: Peter
authors.initials: P
authors.lastname: Scheifele
authors.forename: David
authors.initials: D
authors.lastname: Brown
mesh_terms: D000161:Acoustic Stimulation; D000222:Adaptation, Physiological; D000328:Adult; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011930:Reaction Time / Q000502:physiology*; D012032:Refractory Period, Electrophysiological; D055815:Young Adult