High-Resolution fMRI of Auditory Cortical Map Changes in Unilateral Hearing Loss and Tinnitus
Animal models of hearing loss and tinnitus observe pathological neural activity in the tonotopic frequency maps of the primary auditory cortex. Here, we applied ultra high-field fMRI at 7 T to test whether human patients with unilateral hearing loss and tinnitus also show altered functional activity in the primary auditory cortex. The high spatial resolution afforded by 7 T imaging allowed tonotopic mapping of primary auditory cortex on an individual subject basis. Eleven patients with unilateral hearing loss and tinnitus were compared to normal-hearing controls. Patients showed an over-representation and hyperactivity in a region of the cortical map corresponding to low frequencies sounds, irrespective of the hearing loss and tinnitus range, which in most cases affected higher frequencies. This finding of hyperactivity in low frequency map regions, irrespective of hearing loss range, is consistent with some previous studies in animal models and corroborates a previous study of human tinnitus. Thus these findings contribute to accumulating evidence that gross cortical tonotopic map reorganization is not a causal factor of tinnitus.
KeywordsTinnitus fMRI Primary auditory cortex Neural plasticity
This work was supported by Swiss National Science Foundation Grant 320030_143989 and by the Centre d’Imagerie BioMédicale (CIBM) of the Université de Lausanne, Université de Genève, Hôpitaux Universitaires de Genève, Lausanne University Hospital, École Polytechnique Fédérale de Lausanne, and the Leenaards and Louis-Jeantet Foundations.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
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