Anodal high-definition tDCS over the left dorsolateral prefrontal cortex is associated with autonomic regulation and...

High-definition transcranial direct current stimulation (HD-tDCS) is a non-invasive neuromodulation technique increasingly investigated for its association with executive function performance. Emerging evidence indicates that prefrontal stimulation may also be associated with changes in autonomic regulation, as indexed by heart rate variability (HRV)-a physiological marker linked to adaptive cognitive control and emotional regulation. Within the Neurovisceral Integration Model, prefrontal cortical activity supports dynamic interactions between cognitive and autonomic systems, providing a theoretical framework for examining concurrent variation in HRV and executive performance during left dorsolateral prefrontal cortex (DLPFC) stimulation. Here, we examined the effects of anodal HD-tDCS over the left DLPFC on executive performance and autonomic activity in healthy adults using a randomised, single-blind, crossover design. Participants completed a working memory (N-Back) and an inhibitory control (Stroop) task before and during either anodal or sham HD-tDCS (2 mA, 20 min), while electrocardiogram recordings were collected to derive high-frequency HRV (HF-HRV). Self-reports of negative/positive affect were also collected pre- and during-tDCS. Anodal HD-tDCS was associated with a greater increase in N-Back accuracy relative to sham stimulation. In the Stroop task, accuracy increased during stimulation, whereas reaction time reductions were observed across both stimulation conditions; the reduction in reaction time was greater under anodal than sham stimulation, although the observed pattern should be interpreted cautiously given baseline differences and possible practice-related effects. Anodal stimulation was further associated with greater increases in HF-HRV from baseline compared to sham. Significant associations between HF-HRV and executive performance emerged under anodal stimulation but not under sham. No significant changes were observed in self-reported affect. These findings are consistent with the co-occurrence of cognitive and autonomic changes during anodal stimulation of the left DLPFC, together with an observed association between HF-HRV and selected aspects of executive performance.