The effects on tACS and tRNS on language function: A literature review

Transcranial electrical stimulation (tES) techniques are promising noninvasive tools for modulating language-related neural processes. While transcranial direct current stimulation (tDCS) has been well studied, transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS) remain less characterized. This review synthesizes findings from 11 studies (394 participants) investigating the effects of tACS and tRNS on language processing in neurotypical individuals. Both techniques significantly enhance phonological and semantic processing, with a moderate overall effect size, and with outcomes varying according to stimulation parameters and target regions. The effect remained significant after adjusting for potential publication bias, supporting the robustness of the findings. Prefrontal stimulation was preferentially used for enhancing phonological skills, while stimulation of both temporal and prefrontal areas influenced semantic processing. Future research would benefit from examining network-level effects, developing personalized stimulation protocols, and assessing long-term outcomes - areas that remain underexplored - to advance theoretical understanding and clinical applications.