Cognitive effects of dorsolateral versus medial prefrontal anodal transcranial direct current stimulation in healthy individuals.

OBJECTIVES

Transcranial direct current stimulation (tDCS) is a noninvasive and safe brain stimulation technique with the potential to modulate cognitive functions in both healthy and clinical populations. However, previous studies in healthy individuals have reported mixed results, with outcomes ranging from cognitive enhancement to no observable effects. The present study aimed to investigate the cognitive effects of anodal frontal tDCS in healthy adults, with a particular focus on the medial prefrontal cortex (mPFC), a relatively underexplored target for neuromodulation.

MATERIALS AND

METHODS

Twenty healthy participants completed four randomized anodal tDCS sessions targeting the right and left dorsolateral prefrontal cortex (DLPFC), mPFC, and a sham condition. During stimulation, participants completed a cognitive test battery assessing executive functions, processing speed, memory, and social cognition and included the Trail Making Test (TMT), Letter-Number Sequencing (LNS), Verbal Fluency (VF), Reading the Mind in the Eyes (RME), Symbol Digit Modalities Test (SD), Stroop Test (ST), and Free and Cued Selective Reminding Test (FCSRT).

RESULTS

Active stimulation improved performance in the TMT-A, TMT-B, and SD tests. Specifically, mPFC stimulation yielded superior performance in TMT-A (p = 0.001) and TMT-B (p = 0.015) compared with sham. Left DLPFC stimulation enhanced TMT-A (p = 0.006), while right DLPFC improved TMT-B (p = 0.004) and SD performance vs sham (p = 0.004).

CONCLUSIONS

The findings from this exploratory study suggest that anodal frontal tDCS, particularly targeting the mPFC and DLPFC, may enhance cognitive performance in healthy adults, especially within the domains of executive function and processing speed. Beyond the frequently targeted DLPFC, the mPFC may also represent a promising and underexplored region for future research on cognitive enhancement in healthy populations.