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

Summary

Used resting-state EEG source localization in chronic tinnitus patients split by severity (Tinnitus Handicap Inventory score) versus healthy controls. All tinnitus patients showed abnormal auditory-cortex activation, but the moderate-to-severe group additionally showed enhanced connectivity between the parahippocampus and posterior cingulate gyrus (core Default Mode Network hubs) and between the auditory cortex and insula (a core Salience Network hub), and these insula-related connections correlated directly with handicap/severity scores. The insula is proposed as the hub linking the auditory, salience, and default-mode networks together in more severe tinnitus.

Key findings

• Enhanced parahippocampus-posterior-cingulate connectivity (Default Mode Network) tracks tinnitus severity.
• Enhanced auditory-cortex-to-insula connectivity (Salience Network) tracks tinnitus severity (Tinnitus Handicap Inventory score).
• The insula is proposed as the hub linking auditory processing, salience detection, and the default-mode network in more severe/distressing tinnitus.