Using Resting State Functional Magnetic Resonance To Assess Thalamic Dysfunction And Highlight Network Function In Patients With Chronic Tinnitus

Part 1:Impairments of Thalamic Resting-State Functional Connectivity in Patients with Chronic TinnitusPurpose: The phantom sound of tinnitus is believed to arise from abnormal functional coupling between the thalamus and cerebral cortex.To explore this hypothesis,we used resting-state functional magnetic resonance imaging(f MRI)to compare the degree of thalamocortical functional connectivity in chronic tinnitus patients and controls.Materials and methods: Resting-state f MRI scans were obtained from 30 chronic tinnitus patients and 30 well-matched healthy controls.Thalamocortical functional connectivity was characterized using a seed-based whole-brain correlation method.Results: Functional connections between bilateral anterior central gyrus and left fusiform gyrus and left thalamic seed area were enhanced,while functional connections between right middle temporal gyrus(MTG)and left posterior cerebellar lobe and left thalamic seed area were decreased.The functional connections between the right middle temporal gyrus and the left posterior cerebellar lobe and the right thalamic seed area were enhanced,while the functional connections between the right central anterior gyrus and the right thalamic seed area were decreased.Conclusions: Chronic tinnitus patients have disrupted thalamocortical functional connectivity to selected brain regions which is associated with specific tinnitus characteristics.Resting-state thalamic functional connectivity disturbances may play an important role in neuropathological features of tinnitus.Part 2:Using Resting-state functional magnetic resonance(fmri)to evaluate the salience network function in patients with tinnitusPurpose: To investigate alterations of the functional connectivity using the three nodes in the salience network as seeds in patients with chronic tinnitus.Methods: We performed audiological tests,neuropsychological tests and MRI scanning(including T1 and functional MRI data)on 31 chronic tinnitus patients and33 age-,gender-,education level-,matched healthy controls.Then extracted three nodes from the salience network as seeds,which is anchored in bilateral anterior insula and dorsal anterior cingulate.Functional connectivity,as well as correlations between the functional connections and clinical characteristics were conducted.Results: Both the chronic tinnitus subjects and healthy controls have the normal hearing ability.The dorsal anterior cingulate cortex showed enhanced connectivity with left and right orbitofrontal cortex,but reduced connections with right precentral gyrus and inferior parietal cortex in tinnitus group.And the left anterior insula showed increased connections with left cerebellum lobule VIIb.Additionally,the connectivity between dorsal anterior cingulate cortex and inferior parietal cortex was negatively correlated with the duration of tinnitus(r =-0.538,p = 0.002),and tinnitus questionnaire scores(r =-0.559,p = 0.001)in tinnitus subjects.The dorsal anterior cingulate cortex-precentral gyrus connectivity had negative connections with tinnitus questionnaire scores(r =-0.479,p = 0.006)in tinnitus group.Conclusion: These findings suggest inefficient modulation of the salience network and abnormal connections between the salience network and other brain areas,partly attributing to the neural physiology of chronic tinnitus.