Resting-state networks in chronic tinnitus: Increased connectivity between thalamus and visual areas.

Tinnitus is thought to be associated with aberrant spontaneous activity in the central nervous system. Previous resting-state fMRI findings support this hypothesis and have shown a variety of alterations in neural activity in people with tinnitus compared to people without tinnitus. However, there is little replication of findings. Therefore, the current study aimed to extend on previous findings by investigating eight common resting-state networks (i.e. auditory, default mode, sensorimotor, visual, salience, dorsal attention, frontoparietal and language networks) using a control group (n = 36) and a group of tinnitus patients (n = 46) matched for age, sex and years of education. Hearing profiles matched up to 2 kHz and had a small but significant difference between groups in the high frequency range. Functional connectivity (FC) with dorsolateral prefrontal cortex (DLPFC) was also investigated separately for the first time, as this region is proposed to be core to tinnitus distress symptoms and most often used as a stimulation target in transcranial direct current stimulation (tDCS) research. The results showed that tinnitus patients had increased FC between bilateral thalamus and right visual association cortex compared to control participants. No differences were found with DLPFC, or with any of the resting-state networks (RSN), contrary to previous studies which have reported alterations in several RSNs.