Auditory cortex electrical stimulation suppresses tinnitus in rats.

Recent clinical studies have demonstrated that auditory cortex electrical stimulation (ACES) has yielded promising results in the suppression of patients' tinnitus. However, the large variability in the efficacy of ACES-induced suppression across individuals has hindered its development into a reliable therapy. Due to ethical reasons, many issues cannot be comprehensively addressed in patients. In order to search for effective stimulation targets and identify optimal stimulation strategies, we have developed the first rat model to test for the suppression of behavioral evidence of tone-induced tinnitus through ACES. Our behavioral results demonstrated that electrical stimulation of all channels (frequency bands) in the auditory cortex significantly suppressed behavioral evidence of tinnitus and enhanced hearing detection at the central level. Such suppression of tinnitus and enhancement of hearing detection were respectively demonstrated by a reversal of tone exposure compromised gap detection at 10-12, 14-16, and 26-28 kHz and compromised prepulse inhibition at 10-12 and 26-28 kHz. On the contrary, ACES did not induce behavioral changes in animals that did not manifest any behavioral evidence of tinnitus and compromised hearing detection following the same tone exposure. The results point out that tinnitus may be more related to compromised central auditory processing than hearing loss at the peripheral level. The ACES-induced suppression of behavioral evidence of tinnitus may involve restoration of abnormal central auditory processing.