ABSTRACT
Tinnitus mechanisms remain poorly understood. Our previous functional MRI (fMRI) studies demonstrated an abnormal hyperactivity in the right parietal operculum 3 (OP3) in acoustic trauma tinnitus and during provoked phantom sound perceptions without hearing loss, which lead us to propose a new model of tinnitus. This new model is not directly linked with hearing loss and primary auditory cortex abnormalities, but with a proprioceptive disturbance related to middle-ear muscles. In the present study, a seed-based resting-state functional MRI method was used to explore the potential abnormal connectivity of this opercular region between an acoustic trauma tinnitus group presenting slight to mild tinnitus and a control group. Primary auditory cortex seeds were also explored because they were thought to be directly involved in tinnitus in most current models. In such a model, hearing loss and tinnitus handicap were confounding factors and were therefore regressed in our analysis. Between-groups comparisons showed a significant specific connectivity between the right OP3 seeds and the potential human homologue of the premotor ear-eye field (H-PEEF) bilaterally and the inferior parietal lobule (IPL) in the tinnitus group. Our findings suggest the existence of a simultaneous premotor ear-eye disturbance in tinnitus that could lift the veil on unexplained subclinical abnormalities in oculomotor tests found in tinnitus patients with normal vestibular responses. The present work confirms the involvement of the OP3 subregion in acoustic trauma tinnitus and provides some new clues to explain its putative mechanisms.
ACRONYMS
- CONN
- Connectivity toolbox (matlab toolbox)
- CSF
- Cerebro Spinal Fluid
- ENT
- Ear, Nose and Throat
- EPI
- Echo Planar Imaging
- FDR
- False Discovery Rate
- fMRI
- functional Magnetic Resonance Imaging
- GM
- Grey Matter
- HL
- Hearing levels (dB)
- H-PEEF
- Human premotor ear-eye field
- IPL
- Inferior parietal lobule
- MNI
- Montreal Neurological Institute (brain coordinates system)
- MPRAGE
- Magnetization Prepared Rapid Acquisition GRE
- MR
- Magnetic Resonance
- OP3
- operculum 3
- PEEF
- premotor ear-eye field
- rs-fMRI
- resting-state functional Magnetic Resonance Imaging
- ROI
- Region Of Interest
- sd
- standard deviation
- SPM
- Statistical Parametric Mapping
- TE
- Echo time (ms)
- THI
- Tinnitus Handicap Inventory
- TI
- Inversion Time (ms)
- TR
- Repetition Time (ms)
- WM
- White Matter