Stability of the Cortical Sensory Waveforms, the P1-N1-P2 Complex and T-Complex, of Auditory Evoked Potentials.

Purpose: Atypical cortical sensory waveforms reflecting impaired encoding of auditory stimuli may result from inconsistency in cortical response to the acoustic feature changes within spoken words. Thus, the present study assessed intrasubject stability of the P1-N1-P2 complex and T-complex to multiple productions of spoken nonwords in 48 adults to provide benchmarks for future studies probing auditory processing deficits. Method: Response trials were split (split epoch averages) for each of 4 word types for each subject and compared for similarity in waveform morphology. Waveform morphology association was assessed between 50 and 600 ms, the time frame reflecting spectro-temporal feature processing for the stimuli used in the study.
Results: Using approximately 70 trials in each split epoch, the P1-N1-P2 complex was found to be highly stable, with high positive associations found for all subjects for at least 3 word types. The T-complex was more variable, with high positive associations found for all subjects to at least 1 word type. Conclusions: The P1-N1-P2 split epochs at group and individual levels and the T-complex at group level can be used to assess consistency of neural response in individuals with auditory processing deficits. The T-complex relative to the P1-N1-P2 complex in individuals can provide information pertaining to phonological processing.