Abnormal Functional Connectivity Within Default Mode Network and Salience Network Related to Tinnitus Severity

Area of Science:

• Neuroscience
• Audiology
• Medical Imaging

Background:

• Tinnitus is associated with neural alterations in the cerebral cortex.
• Understanding central nervous system characteristics in tinnitus is crucial for effective treatment.

Purpose of the Study:

• Investigate central nervous system characteristics of tinnitus patients with varying severity.
• Examine neural changes using resting-state electroencephalography (rs-EEG).

Main Methods:

• Recorded rs-EEG in 57 chronic tinnitus patients and 27 healthy controls.
• Categorized patients into moderate-to-severe and slight-to-mild tinnitus groups based on Tinnitus Handicap Inventory (THI) scores.
• Utilized source localization and functional connectivity analyses to assess brain network alterations.

Main Results:

• All tinnitus patients showed auditory cortex activation compared to controls.
• Moderate-to-severe tinnitus group exhibited enhanced connectivity between the parahippocampus and posterior cingulate gyrus.
• Increased functional connectivity between the auditory cortex and insula was observed in the moderate-to-severe group, correlating positively with THI scores.

Conclusions:

• Moderate-to-severe tinnitus is associated with more significant changes in the auditory cortex, insula, parahippocampus, and posterior cingulate gyrus.
• Enhanced connectivity within auditory, salience, and default mode networks suggests widespread neural network dysfunction.
• The insula acts as a core region in a neural pathway involving the auditory cortex and parahippocampus/posterior cingulate gyrus, indicating that tinnitus severity is influenced by a network of brain regions.