Auditory Temporal Integration at Threshold: Evidence of a Cortical Origin

Abstract

A reanalysis of a previous study of wave N100m of the auditory evoked field (AEF) shows that the level dependence of the response amplitude is, near the perceptual threshold, consistent with a model recently developed for the compound action potential of the auditory nerve. The response latency, decremented by a constant transmission delay, is about inversely proportional to the response amplitude. This result, although valid only for very low stimulus levels, supports the view that the considerable increase of the N100m latency with decreasing stimulus level arises, at least in part, from temporal integration. To allow conclusions as to where the temporal integration takes place, first results of a new experiment are presented, in which the auditory evoked potential elicited by a series of eight near-threshold tone-pulses was recorded. Neither wave V of the auditory brainstem response nor the middle-latency response component Pa differed between first and last pulse of the series, suggesting that temporal integration occurs more centrally than primary auditory cortex.