Functional imaging of unilateral tinnitus using fMRI.

CONCLUSIONS This article shows that the inferior colliculus plays a key role in unilateral subjective tinnitus. OBJECTIVES The major aim of this study was to determine tinnitus-related neural activity in the central auditory system of unilateral tinnitus subjects and compare this to control subjects without tinnitus. SUBJECTS AND METHODS Functional MRI (fMRI) was performed in 10 patients (5 males) with unilateral tinnitus (5 left-sided, 5 right-sided) and 12 healthy subjects (6 males); both groups had normal hearing or mild hearing loss. fMRI experiments were performed using a 3T Philips Intera Scanner. Auditory stimuli were presented left or right and consisted of dynamically rippled broadband noise with a sound pressure level of 40 or 70 dB SPL. The responses of the inferior colliculus and the auditory cortex to the stimuli were measured. RESULTS The response to sound in the inferior colliculus was elevated in tinnitus patients compared with controls without tinnitus.