Top- down Modulation of Tinnitus-related Networks Activity using transcranial Random Noise Stimulation

1. BackgroundTinnitus is a common distressful disorder in which auditory and non-auditory areas are involved as a network. Therefore, the multisite protocol of brain stimulation (tRNS) seems effective in relieving tinnitus symptoms. This study aimed to verify the modulatory effects of multisite tRNS on the tinnitus network. 2. MethodThirty-two tinnitus-suffering patients received two consecutive sessions of tRNS (SHAM+ REAL) applied over the T3, T4 (auditory cortex group) and F4, FP1 followed by auditory cortex (multisite group). Each session lasted 20 min and the current was set at 2 mA. 3-min of resting-state EEG were recorded before and immediately after each session. Oscillatory power changes were investigated using the Two-way repeated measure ANOVA. 3. Results After the multisite-tRNS real session, there was a significantly increased power in the alpha-1 band at the auditory and prefrontal cortex accompanied by decreased power in the delta and beta-2 bands in the prefrontal cortex. Standardized low-resolution brain electromagnetic tomography (sLORETA) was used for source anal- ysis and functional connectivity study. sLORETA showed a significant decrease in beta-2 activity in the prefrontal cortex, anterior cingulate cortex, and the parahippocampus and decreased alpha connectivity be- tween the right prefrontal cortex and the left auditory cortex. No significant effects were noticed for the sham session. 4. Conclusions This study showed that tRNS has modulatory effects on the electrical activity of the brain and that targeting prefrontal and auditory areas in sequence could modulate the distress network and multiple hubs in the tinnitus network.