Increased Resting-State Cerebellar-Cerebral Functional Connectivity Underlying Chronic Tinnitus

Abstract

Purpose: Chronic subjective tinnitus may arise from aberrant functional coupling between the cerebellum and the cerebral cortex. To explore this hypothesis, we used resting-state functional magnetic resonance imaging (fMRI) to illuminate the functional connectivity network of the cerebellar regions in chronic tinnitus patients and controls. Methods: Resting-state fMRI scans were obtained from 28 chronic tinnitus patients and 29 healthy controls (well matched for age, sex and education) in this study. Cerebellar-cerebral functional connectivity was characterized using a seed-based whole-brain correlation method. The resulting cerebellar functional connectivity measures were correlated with each clinical tinnitus characteristic. Results: Chronic tinnitus patients demonstrated increased functional connectivity between the cerebellum and several cerebral regions, including the superior temporal gyrus (STG), parahippocampal gyrus (PHG), inferior occipital gyrus (IOG), and precentral gyrus. The enhanced functional connectivity between the left cerebellar Lobule VIIb and the right STG was positively correlated with the Tinnitus Handicap Questionnaires (THQ) score (r = 0.577, p = 0.004). Furthermore, the increased functional connectivity between the cerebellar vermis and the right STG was also associated with the THQ score (r = 0.432, p = 0.039). Conclusions: Chronic tinnitus patients have greater cerebellar functional connectivity to certain cerebral brain regions which is associated with specific tinnitus characteristics. Resting-state cerebellar-cerebral functional connectivity disturbances may play a pivotal role in neuropathological features of tinnitus.

Keywords: cerebellum; functional connectivity; resting-state fMRI; tinnitus.

Figure 1

No significant differences in the auditory thresholds between the tinnitus and control groups. Data are presented as mean ± SEM.

Figure 2

Increased functional connectivity of the different cerebellar seed region of interests (ROIs; bilateral Crus I, bilateral Crus II, bilateral Lobule VIIb and Vermis) in the chronic tinnitus patients compared with the healthy controls. The threshold was set at a p < 0.01 (permutation test corrected). Note that the left side corresponds to the right hemisphere.

Figure 3

Significant correlations between cerebellar functional connectivity and tinnitus characteristics. (A) Positive correlation between the functional connectivity of the left Lobule VIIb to the right superior temporal gyrus (STG) and the tinnitus handicap questionnaires (THQ) score. (B) Positive correlation between the functional connectivity of the vermis to the right STG and the THQ score.