Tinnitus perception and distress is related to abnormal spontaneous brain activity as measured by magnetoencephalography

Background The neurophysiological mechanisms underlying tinnitus perception are not well understood. Surprisingly, there have been no group studies comparing abnormalities in ongoing, spontaneous neuronal activity in individuals with and without tinnitus perception. Methods and Findings Here, we show that the spontaneous neuronal activity of a group of individuals with tinnitus (n = 17) is characterised by a marked reduction in alpha (8-12 Hz) power together with an enhancement in delta (1.5-4 Hz) as compared to a normal hearing control group (n = 16). This pattern was especially pronounced for temporal regions. Moreover, correlations with tinnitus-related distress revealed strong associations with this abnormal spontaneous activity pattern, particularly in right temporal and left frontal areas. Overall, effects were stronger for the alpha than for the delta frequency band. A data stream of 5 min, recorded with a whole-head neuromagnetometer under a resting condition, was sufficient to extract the marked differences. Conclusions Despite some limitations, there are arguments that the regional pattern of abnormal spontaneous activity we found could reflect a tinnitus-related cortical network. This finding, which suggests that a neurofeedback approach could reduce the adverse effects of this disturbing condition, could have important implications for the treatment of tinnitus.