The Effect of Transcranial Random Noise Stimulation (tRNS) over Bilateral Parietal Cortex in Visual Cross-Modal Conflict

Background: Visual cross-modal conflict impairs performance in auditory working memory tasks, and the bilateral inferior parietal cortex (IPC) plays a pivotal role in inhibiting this conflict. However, fewer studies have investigated the role of bilateral IPC in visual cross-modal conflict with semantic and non-semantic distractors. Transcranial random noise stimulation (tRNS) is a relatively new and effective neurostimulation technique for exploring underlying neural mechanisms in cognitive processes by modulating brain excitability. Objective: This study primarily utilized high-frequency tRNS (hf-tRNS) over the bilateral IPC to investigate the potential involvement of the parietal cortex in semantic and non-semantic visual cross-modal conflict. Methods: In a double-blind, sham-controlled, parallel-group design, 42 healthy individuals received sham or tRNS stimulation over the bilateral IPC. Throughout the baseline, online, and offline phases, participants underwent the Auditory Serial Addition Test (PASAT) in two visual conflict conditions (with non-semantic distractor and with semantic distractor). Simultaneously, we assessed behavioral parameters (accuracy and reaction time) in each phase.Results: During online and offline phases, bilateral IPC hf-tRNS significantly enhanced task accuracy in visual cross-modal semantic conflict and reduced task reaction time in non-semantic conflict condition.Conclusion: These results demonstrated that bilateral IPC hf-tRNS could markedly improve the two visual cross-modal conflicts inhibiting, and its effectiveness depended on the types of conflict. These findings contribute to a deeper understanding of the underlying neurophysiological mechanisms of the bilateral IPC in modulating visual cross-modal conflict.