Tinnitus Intensity Dependent Gamma Oscillations of the Contralateral Auditory Cortex

TLDR

Non‑pulsatile tinnitus is a subjective phantom sound affecting 10–15 % of people, linked to hyperactivity and reorganization of the auditory cortex, and MEG studies show gamma‑band activity in the contralateral auditory cortex correlates with its presence. The study aims to investigate the relationship between objective gamma‑band activity in the contralateral auditory cortex and subjective tinnitus loudness scores. Source analysis of resting‑state EEG gamma‑band oscillations in 15 unilateral tinnitus patients revealed a strong positive correlation with Visual Analogue Scale loudness scores. Auditory phantom percepts exhibit sound‑level dependent activation of the contralateral auditory cortex similar to normal audition, indicating tinnitus loudness is encoded by gamma activity but may not alone drive perception.

Abstract

Background Non-pulsatile tinnitus is considered a subjective auditory phantom phenomenon present in 10 to 15% of the population. Tinnitus as a phantom phenomenon is related to hyperactivity and reorganization of the auditory cortex. Magnetoencephalography studies demonstrate a correlation between gamma band activity in the contralateral auditory cortex and the presence of tinnitus. The present study aims to investigate the relation between objective gamma-band activity in the contralateral auditory cortex and subjective tinnitus loudness scores. Methods and Findings In unilateral tinnitus patients (N = 15; 10 right, 5 left) source analysis of resting state electroencephalographic gamma band oscillations shows a strong positive correlation with Visual Analogue Scale loudness scores in the contralateral auditory cortex (max r = 0.73, p<0.05). Conclusion Auditory phantom percepts thus show similar sound level dependent activation of the contralateral auditory cortex as observed in normal audition. In view of recent consciousness models and tinnitus network models these results suggest tinnitus loudness is coded by gamma band activity in the contralateral auditory cortex but might not, by itself, be responsible for tinnitus perception.