Resting-state functional connectivity and local activity differences across bothersome and non-bothersome tinnitus...

Area of Science:

• Neuroimaging
• Auditory Neuroscience
• Clinical Neuroscience

Background:

• Tinnitus, characterized by auditory perception without external stimuli, significantly impacts quality of life.
• Understanding the neural underpinnings of tinnitus severity is crucial for developing targeted interventions.
• Previous research suggests altered brain functional connectivity in tinnitus, but distinctions based on symptom severity remain unclear.

Purpose of the Study:

• To investigate resting-state functional magnetic resonance imaging (fMRI) differences between individuals with bothersome tinnitus (BT), non-bothersome tinnitus (NBT), and healthy controls.
• To characterize functional connectivity (FC), regional homogeneity (ReHo), and fractional amplitude of low-frequency fluctuations (fALFF) related to tinnitus phenotype.
• To explore associations between neuroimaging findings and clinical/audiological measures.

Main Methods:

• A case-control study involving 61 BT patients, 52 NBT patients, and 50 non-tinnitus controls.
• Resting-state fMRI data acquisition and analysis using fALFF, ReHo, and seed-based FC with bilateral temporal lobe regions of interest.
• Statistical comparisons using ANCOVA, controlling for covariates, with cluster-level FDR correction (p < 0.05).

Main Results:

• Significant group differences in resting-state FC between the temporal lobe seed and the left ACC/mOFC cluster were observed, with stronger connectivity in BT than NBT.
• Lower ReHo values in the medial superior frontal gyrus were found in NBT compared to both BT and controls.
• fALFF analyses revealed region-specific differences across multiple brain areas, most consistently between BT and NBT. Sensitivity analyses suggested some differences may relate to tinnitus loudness.

Conclusions:

• Resting-state FC, fALFF, and ReHo measures demonstrate phenotype-related functional differences between BT and NBT groups.
• Key imaging measures did not significantly differ between BT and healthy controls, suggesting these are not BT-specific abnormalities.
• The findings highlight group-level functional imaging features across tinnitus phenotypes, potentially influenced by tinnitus loudness.