title: Brain regions responsible for tinnitus distress and loudness: a resting-state FMRI study.
abstract: Subjective tinnitus is characterized by the perception of phantom sound without an external auditory stimulus. We hypothesized that abnormal functionally connected regions in the central nervous system might underlie the pathophysiology of chronic subjective tinnitus. Statistical significance of functional connectivity (FC) strength is affected by the regional autocorrelation coefficient (AC). In this study, we used resting-state functional MRI (fMRI) and measured regional mean FC strength (mean cross-correlation coefficient between a region and all other regions without taking into account the effect of AC (rGC) and with taking into account the effect of AC (rGCa) to elucidate brain regions related to tinnitus symptoms such as distress, depression and loudness. Consistent with previous studies, tinnitus loudness was not related to tinnitus-related distress and depressive state. Although both rGC and rGCa revealed similar brain regions where the values showed a statistically significant relationship with tinnitus-related symptoms, the regions for rGCa were more localized and more clearly delineated the regions related specifically to each symptom. The rGCa values in the bilateral rectus gyri were positively correlated and those in the bilateral anterior and middle cingulate gyri were negatively correlated with distress and depressive state. The rGCa values in the bilateral thalamus, the bilateral hippocampus, and the left caudate were positively correlated and those in the left medial superior frontal gyrus and the left posterior cingulate gyrus were negatively correlated with tinnitus loudness. These results suggest that distinct brain regions are responsible for tinnitus symptoms. The regions for distress and depressive state are known to be related to depression, while the regions for tinnitus loudness are known to be related to the default mode network and integration of multi-sensory information.
authors.affiliation: Department of Anatomy and Cell Biology, Graduate School of Wakayama Medical University, Wakayama, Japan. tueyama@wakayama-med.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueyama
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Donishi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ukai
authors.forename: Yorihiko
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Muneki
authors.initials: M
authors.lastname: Hotomi
authors.forename: Noboru
authors.initials: N
authors.lastname: Yamanaka
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Shinosaki
authors.forename: Masaki
authors.initials: M
authors.lastname: Terada
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Kaneoke
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D003863:Depression / Q000150:complications*; D005260:Female; D006801:Humans; D008144:Loudness Perception; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology; D012146:Rest; D014012:Tinnitus / Q000150:complications* / Q000503:physiopathology*; D055815:Young Adult