Auditory middle-latency response: intramodal and intermodal interactions.

Intramodal and intermodal interactions have been studied in generators of the auditory middle-latency response (MLR). The MLRs were recorded to the wide-band clicks. Similar clicks or electric shocks to the median nerve served as conditioning stimuli. A procedure was employed permitting to avoid distortions of test MLRs due to superimposition upon potentials to the conditioning stimuli. A rapid recovery of responsiveness in MLR generators was revealed in intramodal experiments. Poorly discernible test MLRs were identified at conditioning interval of 10 ms, while already at interval of 50 ms the MLR restoration was completed. No effects of shocks upon MLRs were evident in intermodal experiments. The starting knee was only altered in most test MLRs, outlining a narrow strip of intermodal interaction. The sources of the MLR are discussed and a subcortical rather than cortical, polylevel rather than monolevel, monomodal rather than polymodal nature of the MLR is proposed.