Resting-state Networks in Tinnitus

Abstract

Chronic subjective tinnitus is the constant perception of a sound that has no physical source. Brain imaging studies show alterations in tinnitus patients’ resting-state networks (RSNs). This scoping review aims to provide an overview of resting-state fMRI studies in tinnitus, and to evaluate the evidence for changes in different RSNs. A total of 29 studies were included, 26 of which found alterations in networks such as the auditory network, default mode network, attention networks, and visual network; however, there is a lack of reproducibility in the field which can be attributed to the use of different regions of interest and analytical methods per study, and tinnitus heterogeneity. Future studies should focus on replication by using the same regions of interest in their analysis of resting-state data, and by controlling adequately for potential confounds. These efforts could potentially lead to the identification of a biomarker for tinnitus in the future.

Atypical functional hierarchy contributed to the tinnitus symptoms in patients with vestibular schwannoma

“…Gentil et al (2019) reported that cerebral regional homogeneity was significantly reduced in the contralateral primary auditory cortex and increased in ipsilateral supramarginal and angular gyri to the tinnitus side. Moreover, resting-state network activities involving the auditory network, default mode network, attention networks, visual network, etc., were also confirmed to have significant changes in patients with chronic tinnitus (Kok et al, 2022). Inspired by these neuroimage studies of primary tinnitus, we also conducted a functional gradient study for VS tinnitus.…”

Disruptions of default mode network and precuneus connectivity associated with cognitive dysfunctions in tinnitus

“…In addition, some studies used an “eyes-open” paradigm and others used an "eyes-closed” paradigm for the resting-state acquisition, which might explain some of the heterogeneous findings 32 . It has been previously demonstrated that the choice of paradigm significantly impacts resting-state functional connectivity of visual, auditory and sensorimotor networks 33 . We employed an “eyes-open” approach and our groups were matched in terms of age, sex and hearing loss.…”

Tinnitus-frequency specific activity and connectivity: A MEG study

“…In addition, most of them employed ROI-based analyses, which define regions of interest a-priori and, as a consequence, areas important to the tinnitus network might have been neglected. Thus, a lack or replicability has been pointed out in a recent review ( Kok et al, 2022 ). In our recent study ( Paraskevopoulos et al, 2019 ), by using directed functional connectivity metrics, we applied a whole-head analysis and were able to investigate connectivity differences of intrinsic cortical networks underpinning tinnitus, without predefining the regions of the network.…”

“…Several authors assume that this is due to cortical reorganization ( Eggermont and Roberts, 2004 , Eggermont and Roberts, 2012 ; Christo Pantev et al, 2012 , Stein et al, 2015a , Stein et al, 2015b ), by which each source contributes to a different extent ( Maudoux et al, 2012 , Mirz et al, 1999 ). Two reviews ( Husain and Schmidt, 2014 , Kok et al, 2022 ) supplied an overview over global changes in tinnitus patients and suggested that several resting-state brain networks such as the default mode network, auditory attention network, and functionally coupled regions in the limbic system among others are maladaptively reorganized in tinnitus patients. The principal brain structures involved in these networks comprise areas such as the posterior cingulate cortex, the medial prefrontal cortex, inferior frontal cortex, medial prefrontal cortex, the insula, and the para -hippocampus (see also Besteher et al, 2019 ).…”