Hearing Loss and Tinnitus: Uncover the Mechanism of Tinnitus using Resting-State Functional Magnetic Resonance Imaging (rs-fMRI) Technologies

Abstract

Objective: This project aimed to investigate the differences in the intra-regional brain activity and inter-regional functional connectivity in subjects with tinnitus only and subjects with hearing loss and tinnitus, using resting-state functional magnetic resonance imaging (rs-fMRI) technologies, including the Amplitude of Low-Frequency Fluctuations (ALFF), regional homogeneity (ReHo), and Voxel-Wise Functional Connectivity (FC). Method: We acquired rs-fMRI scans from 82 subjects (21 tinnitus subjects without hearing loss, 32 subjects with tinnitus and hearing loss, and 29 subjects as healthy control). Age, gender, and year of education were matched across all three groups. We consecutively performed ALFF, ReHo, and Voxel-Wise Functional Connectivity (FC) for all subjects. Result: Compared with the control group (CN), subjects with tinnitus only (T group) and with tinnitus and hearing loss (T+H group) manifested significantly reduced ALFF and ReHo activity within the left and right dorsolateral superior frontal gyrus (SFG). Additional Voxel-Wise Functional Connectivity (FC) revealed decreased connectivity between the dorsolateral SFG (left and right) and right Superior Parietal Gyrus (SPG), right Middle Frontal Gyrus (MFG), and left medial Superior Frontal Gyrus (mSFG) within these two groups. No significant differences were observed between the T and T+H groups. Conclusion: Upon analyzing our data, we suggested disruptions in brain regions responsible for attention and stimuli monitoring and orientations contribute to tinnitus generation. Thus, hearing loss might not be the primary cause of tinnitus.

Recent-Onset and Persistent Tinnitus: Uncover the Differences in Brain Activities using Resting-State Functional Magnetic Resonance Imaging Technologies

“…The calculated averaged square root was taken as the ALFF. Finally, the ALFF of each voxel was divided by the global mean ALFF value for standardization (Du et al, 2022).…”

“…The ReHo value of each voxel was then standardized by partitioning the primal value using the global mean ReHo value. Finally, the data were smoothed with a Gaussian kernel of 6 mm full-width at half maximum (FWHM) for further statistical analysis (Du et al, 2022).…”

“…Afterward, the procedures were carried out as follows: spatially normalized into the stereotactic space of the Montreal Neurological Institute (MNI) (resampling voxel size = 3 × 3 ×3 mm 3 ) and smoothed using a Gaussian kernel of 6 mm full width at half-maximum (FWHM), detrending, and filtering (0.01-0.08 Hz). Subjects with a head motion with more than 2.0 mm displacement or a 2.0-degree rotation in the 𝑥𝑥, 𝑦𝑦, or 𝑧𝑧 directions were excluded (Du et al, 2022).…”

“…Minami and colleagues reported that tinnitus patients with hearing loss showed a statistically significant reduction in auditory-related functional connectivity than the control group (Minami et al, 2018). Finally, our previous project, using ALFF, ReHo, and Voxel-Wise Functional Connectivity technologies, revealed that disruptions in brain regions responsible for attention and stimuli monitoring and orientations could lead to tinnitus (Du et al, 2022). Tinnitus has different forms, degrees of severity, and onset duration, which can only be described by patients' testimony and corresponding symptoms.…”