Thalamocortical dysrhythmia underpin the log-dynamics in phantom sounds.

Abstract

Abstract Electrophysiological tinnitus research, such as EEG studies, typically investigates the irregularities in separate frequency bands. These frequency bands are coupled, such that the higher oscillation frequencies are nested (phase–amplitude coupled) on the lower frequencies, resulting in a 1/f power spectrum. The changes in the 1/f slope of the power spectrum in tinnitus patients are unexplored. Deviations from the 1/f pattern also reflect a change toward a more lattice (steeper slope) or random network (flatter slope) and relate to the amount of information in a network. In this study, we investigate the 1/f slope in the resting-state EEGs of tinnitus patients and relate these findings to proposed tinnitus mechanisms. Our data show that tinnitus is characterized by a slope that is flattened in comparison to the control group and that the tinnitus loudness percept correlates the steepness of the slope of the power spectrum in resting-state EEG signals for the left auditory cortex and left parahippocampus. The steepness of the slope is predominantly related to an increase in theta activity and its minor increase in gamma activity, suggesting that the slope is deviating toward white noise. These results should motivate further research into this hitherto elusive form of brain activity that resides behind the mask of the universal 1/f power spectrum observed across nature.