Activity in the dorsal cochlear nucleus of hamsters previously tested for tinnitus following intense tone exposure.

Chronic increases in spontaneous multiunit activity can be induced in the dorsal cochlear nucleus (DCN) of hamsters by intense sound exposure (Kaltenbach and McCaslin, 1996). It has been hypothesized that this hyperactivity may represent a neural code that could underlie the sound percepts of tinnitus. The goal of the present study was to determine whether hyperactivity could be demonstrated in animals that had previously been tested for tinnitus, and, if so, whether animals differing in their behavioral evidence for tinnitus also differ in their levels of spontaneous activity. The results showed not only that levels of activity in exposed animals were higher than those in control animals, but the degree to which the activity was increased was related to the strength of the behavioral evidence for tinnitus. These findings are consistent with the hypothesis that hyperactivity in the DCN may be a physiological correlate of noise-induced tinnitus.