Inhibition-induced plasticity in tinnitus patients after repetitive exposure to tailor-made notched music.
Notch-filtered music has been shown to induce frequency-specific inhibition. Here, we investigated which cortical structures are affected by tailor-made notched music (TMNM) in tinnitus patients and how this inhibition-induced plasticity develops over time. Nine subjects suffering from chronic tonal tinnitus listened to music passing through a notch-filter centered at the patient's individual tinnitus frequency (TMNM) for three hours on three consecutive days. Before and after each listening session, a tone at the tinnitus frequency and a control tone of 500 Hz were presented in the magnetoencephalograph. Subjective tinnitus loudness was measured via visual analog scales. TMNM exposure reduced subjective tinnitus loudness and neural activity evoked by the tinnitus tone in temporal, parietal and frontal regions within the N1m time interval. Reduction of temporal and frontal activation correlated significantly with tinnitus loudness decline. Reduction of tinnitus related neural activity persisted and accumulated over three days. Inhibition-induced plasticity occurs in a cortical network, known to be crucial for tinnitus perception. This cortical reorganization evolves fast and accumulates across sessions. This study extends previous work on inhibition-induced plasticity, as it demonstrates the involvement of parietal and frontal areas and discovers a cumulative effect of cortical reorganization in tinnitus patients.