Investigating Neural Dynamics in Tinnitus Using Constrained Independent Component Analysis.

Tinnitus is a neurological condition characterized by the perception of ringing or other phantom sounds in the absence of external auditory stimuli. It affects an estimated 10%-15% of adults worldwide and can significantly affect sleep and mood. Neuroimaging techniques, particularly functional Magnetic Resonance Imaging (fMRI), have been widely used to investigate the auditory system and brain networks in tinnitus. Resting-state fMRI (rs-fMRI), a noninvasive approach, is particularly effective in examining spontaneous neural activity and functional connectivity (FC) across brain regions. This study investigated alterations in FC in individuals with chronic, non-bothersome tinnitus due to acoustic trauma using both static FC (sFC) and dynamic FC (dFC) analyses. A constrained independent component analysis was applied to identify five resting-state networks across the 23 regions of interest. sFC analysis revealed increased connectivity between the posterior cingulate cortex (a key region in the default mode network) and left angular gyrus (in the executive control network) in the tinnitus group. The dFC analysis showed that patients with tinnitus spent significantly more time in a weakly connected state, whereas healthy controls predominantly occupied a more segregated and strongly connected state. Findings suggest reduced network differentiation and altered temporal stability in individuals with non-bothersome tinnitus, potentially influenced by hearing loss. These alterations in both static and dynamic FC patterns provide insights into the neural underpinnings of tinnitus and its interaction with large-scale brain networks. Impact Statement This study demonstrated the value of combining resting-state functional magnetic resonance imaging, constrained independent component analysis, and dynamic functional connectivity to investigate the neural underpinnings of non-bothersome tinnitus. By examining both static and time-varying connectivity across five major resting-state networks, we identified specific alterations in the default mode network, executive control network, and salience network. Our findings suggest that tinnitus affects brain regions involved in attention, memory, and emotion beyond the auditory system. These results offer novel insights into the temporal dynamics of brain networks in tinnitus and may help guide future research on network-level therapeutic strategies.