Time evolution of acoustic 'information' processing in the mesencephalon of Wistar rats

A traditional analysis of intra-encephalic auditory evoked potentials does not highlight the dynamical evolution of the auditory 'information' process ing in neither time nor space. This work presents a method for tracing such signal evolution throughout the primary auditory pathway in the mesencepha lon of adult anesthetized Wistar rats, using a unilateral 3 kHz tone burst stimulus. The results of the acoustic evoked potentials mapping are present ed as conventional 20 ms recordings and re-analyzed in intervals of 1 ms-ti me windows. The parameter used, as an 'activity' correlate, was the maximum /minimum voltage difference obtained from each time window. The methodology used clearly indicates sequential signal propagation from the dorsal and v entral nuclei of the lateral lemniscus up to the inferior colliculus. (C) 2 000 Elsevier Science Ireland Ltd. All rights reserved.