Habituation deficit in auditory event-related potentials in tinnitus complainers.

According to Hallam's habituation theory of tinnitus, most of the suffering caused by tinnitus is due to difficulties in habituation to the perceived tinnitus sound. Thus tinnitus complainers are assumed to display a less pronounced habituation as compared to tinnitus non-complainers. In the present study, an experimental test of this theory was undertaken using event-related potentials (ERPs) as indicators of habituation to exogenously administered tone pips. In 22 patients (10 tinnitus complainers and 12 tinnitus non-complainers) and 10 healthy controls, the habituation of ERPs to series of auditory stimuli across four consecutive trials was studied. Diminuition of the N(1) and P(2) amplitudes of the ERPs was taken to measure the habituation process across the trials. Tinnitus complainers showed a less distinct habituation of the N(1)-P(2) amplitude difference (vertex potential) compared to tinnitus non-complainers. The results are in accordance with Hallam's theory and support the notion that patients with a severe tinnitus fail to properly habituate to auditory stimuli.