Modulating altered sensory prediction using bilateral auditory cortex high-definition transcranial random noise...

To assess the combined effect of high-definition transcranial random noise stimulation (HD-tRNS) of bilateral auditory cortex and acoustic stimulation (AS) on auditory evoked potentials and tinnitus perception.

A double-blind, randomized, controlled, within-subject crossover trial was conducted with thirteen adults with chronic tinnitus. Each participant completed four sessions, at least 48 h apart, consisting of active HD-tRNS + AS, active HD-tRNS alone, sham HD-tRNS + sham AS and sham HD-tRNS alone. Auditory evoked potentials (including mismatch negativity) and tinnitus characteristics were measured before and after each session.

Active electric and bimodal stimulation significantly modulated auditory evoked potentials, unlike their sham equivalents. Bimodal stimulation produced significant changes in MMN amplitude that countered the tinnitus-related alteration in processing intensity deviants. However, these effects did not survive family-wise correction in this complex design. Bimodal and bimodal-sham stimulation reduced objective loudness by >3 dB.

HD-tRNS, particularly when combined with AS, may induce changes in auditory-system excitability and acutely alter neural processing and loudness perception in tinnitus.

Combining acoustic and electric stimulation is a promising approach for basic research and clinical applications in auditory neuroscience, providing new insights into neuroplasticity in an altered auditory system. This is the first study to measure the modifiability of evoked neural correlates in tinnitus.