THE FUNCTIONAL NEUROANATOMY OF TINNITUS - EVIDENCE FOR LIMBIC SYSTEM LINKS AND NEURAL PLASTICITY

We used PET to map brain regions responding to changes in tinnitus lou dness in four patients who could alter tinnitus loudness by performing voluntary oral facial movements (OFMs). Cerebral blood flow was measu red in four patients and six controls at rest, during the OFM, and dur ing stimulation with pure tones. OFM-induced loudness changes affected the auditory cortex contralateral to the ear in which tinnitus was pe rceived, whereas unilateral cochlear stimulation caused bilateral effe cts, suggesting a retrocochlear origin for their tinnitus. Patients, c ompared with controls, showed evidence for more widespread activation by the tones and aberrant links between the limbic and auditory system s. These abnormal patterns provide evidence for cortical plasticity th at may account for tinnitus and associated symptoms. Although audiolog ic symptoms and examinations of these patients were typical, the unusu al ability to modulate tinnitus loudness with an OFM suggests some cau tion may be warranted in generalizing these findings.