A novel approach to study the behavioral, neural and phenomenological impact of prefrontal HD-tDCS on conflict resolution

Abstract

This study aimed to investigate the effects of high-definition transcranial direct current stimulation (HD-tDCS) on conflict resolution, focusing on behavioral performance, neural activity, and subjective experience. Sixty participants were randomly assigned to anodal, cathodal, or sham HD-tDCS groups and completed a 30-minute flanker task during stimulation. Using a comprehensive methodological approach, including Drift-Diffusion Modeling (DDM), EEG analysis, Lempel-Ziv complexity, and Temporal Experience Tracing (TET), we assessed the cognitive, neural, and phenomenological effects of stimulation. Behavioral results indicated no significant improvements in reaction times or accuracy across the stimulation groups. Similarly, DDM parameters showed no effect of HD-tDCS on cognitive processes. However, EEG data revealed a significant reduction in neural complexity, in the anodal group during resting-state, suggesting neural reorganization. Subjective experience analysis identified two distinct clusters of task-related feelings, though time spent in these experiential states did not differ between groups. Interestingly, sensation of stimulation was significantly higher for anodal stimulation than sham when analyzed as a single dimension. Despite null behavioral effects, this study provides important insights into the neural and subjective responses to HD-tDCS and emphasizes the value of advanced analytic techniques in examining brain stimulation effects. These findings contribute to the ongoing debate about the efficacy of tDCS in cognitive enhancement.