Acupuncture is recommended for the relief of chronic tinnitus in traditional Chinese medicine, but the underlying neural mechanism remains unclear. The human brain is a dynamic system, and it’s unclear about acupuncture’s effects on the dynamic functional connectivity of chronic tinnitus. Therefore, this study based on resting-state functional magnetic resonance imaging (fMRI) investigates abnormal dynamic functional connectivity in chronic tinnitus patients and the neural activity change evoked by acupuncture treatment for tinnitus.
In this study, 17 chronic tinnitus patients and 22 age- and sex-matched normal subjects were recruited, and their tinnitus-related scales and hearing levels were collected. The fMRI data were measured before and after acupuncture, and then sliding-window and k-means clustering methods were used to calculate dynamic functional connectivity and perform clustering analysis, respectively.
We found that, compared with the normal subjects, chronic tinnitus patients had higher temporal variability of dynamic functional connectivity between the supplementary motor area and medial part of the superior frontal gyrus, and it positively correlated with hearing loss. Clustering analysis showed higher transition probability between connection states in chronic tinnitus patients, and it was positively correlated with tinnitus severity.
Furthermore, the findings showed that acupuncture treatment might improve tinnitus. dynamic functional connectivity between the posterior cingulate gyrus and angular gyrus in chronic tinnitus patients after acupuncture showed significantly decreased, and it positively correlated with the improvement of tinnitus. Clustering analysis showed that acupuncture treatment might promote chronic tinnitus patients under lower dynamic functional connectivity state, and it also positively correlated with the improvement of tinnitus.
This study suggests that acupuncture as an alternative therapy method might decrease the tinnitus severity by decreasing the time variability of dynamic functional connectivity in chronic tinnitus patients.