1983 Volume 26 Issue 6 Pages 716-721
By means of digital filtering technique, averaged auditory brainstem responses were devided into slow component with a frequency range of 50-300Hz and fast one with 400-1500Hz. Relationship between two components and stimulus intensity or interstimulus interval (ISI) was investigated.
The slow component and wave V of the fast component showed almost the same latency change; a prolongation of the latency with decreasing stimulus intensity and ISI.
As stimulus intensity was increased, the amplitude of wave V increased monotonically, while the slow component amplitude tended to level off at around 55-70dBSL.
When stimulus interval decreased to 11ms, the amplitude of the wave V and the slow component decreased to approximately 75% and 90% of the amplitude at 125ms ISI. The slow component amplitude showed characteristic change to decreasing ISI; a marked increase at 25ms ISI and a slight decrease at 42ms ISI, these changes of the amplitude can be explained by superimposition and cancellation with Pa and Nb of middle latency response as seen in 40Hz event related potential designated by Galambos et al (1981).
These results suggest that the two components of ABR are of different origins. The slow component seems to be generated through a pathway which is much more resistant to adaptation.