Disrupted Intraregional Brain Activity and Functional Connectivity in Unilateral Acute Tinnitus Patients With Hearing Loss

Abstract

PurposeThe present study combined fractional amplitude of low-frequency fluctuations (fALFF), regional homogeneity (ReHo), and functional connectivity (FC) to explore brain functional abnormalities in acute tinnitus patients (AT) with hearing loss.MethodsWe recruited twenty-eight AT patients and 31 healthy controls (HCs) and ran resting-state functional magnetic resonance imaging (fMRI) scans. fALFF, ReHo, and FC were conducted and compared between AT patients and HCs. After that, we calculated correlation analyses among abnormal fALFF, ReHo, FC, and clinical data in AT patients.ResultsCompared with HCs, AT showed increased fALFF values in the right inferior temporal gyrus (ITG). In contrast, significantly decreased ReHo values were observed in the cerebellar vermis, the right calcarine cortex, the right precuneus, the right supramarginal gyrus (SMG), and the right middle frontal gyrus (MFG). Based on the differences in the fALFF and ReHo maps, the latter of which we defined as region-of-interest (ROI) for FC analysis, the right ITG exhibited increased connectivity with the right precentral gyrus. In addition, the right MFG demonstrated decreased connectivity with both the bilateral anterior cingulate cortex (ACC) and the left precentral gyrus.ConclusionBy combining ReHo, fALFF, and FC analyses, our work indicated that AT with hearing loss had abnormal intraregional neural activity and disrupted connectivity in several brain regions which mainly involving the non-auditory area, and these regions are major components of default mode network (DMN), attention network, visual network, and executive control network. These findings will help us enhance the understanding of the neuroimaging mechanism in tinnitus populations. Moreover, these abnormalities remind us that we should focus on the early stages of this hearing disease.

Aberrant Functional and Causal Connectivity in Acute Tinnitus With Sensorineural Hearing Loss

“…Our study also found that non-auditory associative regions reduced connectivity with the STG, which included the cerebellum, PreCG, and the PoCG. The cerebellum is considered as an important hub in detecting auditory afferent and sound processing (Zhou et al, 2019), as well as plays a critical role in a gating control mechanism (Micarelli et al, 2017). Our finding is in line with this previous study, which shows a reduction of cerebellum activity in acute tinnitus.…”

“…Furthermore, many pathophysiological models have also been developed to explain the mechanism of chronic tinnitus, including central gain, neural synchrony, frontostriatal gating, noise canceling deficits, and global workspace (Vanneste et al, 2011;Hashmi et al, 2013;Elgoyhen et al, 2015;Rauschecker et al, 2015;Wallhäusser-Franke et al, 2017;Cai et al, 2018;Zhou et al, 2019). However, few studies have investigated central neural processing during an acute period, thus, the mechanism of acute tinnitus remains unclear.…”

“…A recent study by Zhou et al (2019) investigated the alterations of brain function using resting-state functional magnetic resonance imaging (rs-fMRI) in 28 patients with unilateral acute tinnitus and hearing loss. Abnormal neural activity and altered connectivity in both the auditory and non-auditory cortex were found.…”

“…Abnormal neural activity and altered connectivity in both the auditory and non-auditory cortex were found. The disrupted cortex regions included increased activity in the right temporal gyrus and decreased in the cerebellar vermis, the right calcarine cortex, the right precuneus, the right supramarginal gyrus (SMG), as well as the right middle frontal gyrus (MFG) in acute tinnitus, which associated with the DMN, attention network, visual network, and executive control network (Zhou et al, 2019). In a recent electroencephalography (EEG) study, reduced activity in the left frontal cortex, decreased connectivity between the temporal gyrus and the SMG, as well as the central cingulate gyrus and frontal gyrus in a comparison between 25 acute tinnitus subjects and 27 healthy controls, was shown (Cai et al, 2019).…”

Neuroanatomical Alterations in Patients With Tinnitus Before and After Sound Therapy: A Combined VBM and SCN Study

“…This result showed that after a long period of treatment, the hearing information storage and emotion of tinnitus patients had a certain degree of recovery. The calcarine gyrus is an important part of the primary visual cortex and the main relay station for transmitting retinal signals; thus, changes in the calcarine gyrus may result from patients attending to phantom auditory sensations and having the visual areas contemporaneously activated (51). Our previous research has also shown that the local activity and functional connectivity of the primary auditory cortex were enhanced (52).…”