Binaural Interaction Component of Auditory Evoked Potentials: ABR vs. 80-Hz ASSR and AMLR vs. 40-Hz ASSR

The Binaural Interaction Component (BIC) is an electrophysiological index to evaluate binaural auditory processing. The generators of the auditory steady-state response (ASSR) to high- and low-modulation frequency are possibly similar to generator sites of the auditory brainstem response (ABR) and auditory middle latency response (AMLR), respectively. The aim of this study was to compare the BIC of the ABR with the BIC of the ASSR using high modulation frequency (MF) and the BIC AMLR with the BIC of the ASSR using low MF in the same subject. The BIC of ABR and ASSR using high MF (79Hz and 94Hz) and AMLR and ASSR using low MF (39Hz and 49Hz) was studied in 15 young female adults with normal hearing. The stimuli consisted of 75 dB nHL rarefaction clicks presented monaurally and binaurally. Results showed that the baseline-to-peak amplitudes (uV) of the 80 Hz ASSR-BIC were smaller than the ABR-BIC wave V (p \u3c 0.0005), which could be due to the use of slow stimulus rate for ABR. In contrast, 40 Hz ASSR-BIC amplitudes were larger than the AMLR-BIC Na and Pa amplitudes (p \u3c 0.005). Latency findings for the ABR-BIC and 80 Hz ASSR-BIC suggest presence of similar BI mechanisms at the brainstem level. In contrast, prolonged latency of the AMLR-BIC than 40 Hz ASSR-BIC suggests presence of different BI mechanisms at the subcortical level. Results also suggest that different neural mechanisms may be responsible for fast stimulation rate (BIC-ABR and 80 Hz ASSR) versus low stimulation rate (AMLR and 40 Hz ASSR) components