The effect of transcranial random noise stimulation (tRNS) over bilateral parietal cortex in visual cross-modal conflicts

In complex sensory environments, visual cross-modal conflicts often affect auditory performance. The inferior parietal cortex (IPC) is involved in processing visual conflicts, namely when cognitive control processes such as inhibitory control and working memory are required. This study investigated the effect of bilateral IPC tRNS on reducing visual cross-modal conflicts and explored whether its efficacy is dependent on the conflict type. Forty-four young adults were randomly allocated to receive either active tRNS (100-640 Hz, 2-mA for 20 min) or sham stimulation. Participants repeatedly performed tasks in three phases: before, during, and after stimulation. Results showed that tRNS significantly enhanced task accuracy across both semantic and non-semantic conflicts compared to sham, as well as a greater benefit in semantic conflict after stimulation. Correlation analyses indicated that individuals with lower baseline performance benefited more from active tRNS during stimulation in the non-semantic conflict task. There were no significant differences between groups in reaction time for each conflict type task. These findings provide important evidence for the use of tRNS in reducing visual cross-modal conflicts, particularly in suppressing semantic distractors, and highlight the critical role of bilateral IPC in modulating visual cross-modal conflicts.