Effects of transcranial direct current stimulation and mindful walking on directional brain connectivity: An isolated effective coherence analysis

Introduction: Mindfulness and transcranial direct current stimulation (tDCS) modulate brain networks implicated in psychopathology. This study investigated the synergistic effects of concurrent anodal tDCS over the left dorsolateral prefrontal cortex (DLPFC) and treadmill walking for Focused Mindfulness (TW-FM) on effective directional brain connectivity for focused mindfulness.

Methods: Seventy-seven healthy participants were assigned to three groups: Active tDCS with Mindful walking (Active-MW), Sham tDCS with MW (Sham-MW), or Active tDCS during Resting State (Active-RS) by combining data sets from two individual studies. Isolated effective coherence (iCoh) in the theta and alpha bands was analyzed using standardized low-resolution brain electromagnetic tomography (sLORETA).

Results: Active tDCS significantly reduced information flow from the posterior cingulate cortex (PCC) to the rostral anterior cingulate cortex (rACC) within the Default Mode Network (DMN). Furthermore, the mindfulness intervention significantly attenuated the flow from the rACC to the medial prefrontal cortex (mPFC) and the flow from the left inferior parietal lobe to the mPFC. Notably, Active tDCS strengthened interhemispheric Executive Control Network (ECN) connectivity from the right to the left DLPFC. Conversely, the Active-MW group exhibited reduced alpha band connectivity from the right DLPFC to the rACC compared to the other groups.

Conclusions: The combined intervention elicited hierarchical decoupling of the DMN. tDCS suppressed bottom-up emotional pathways, whereas mindfulness inhibited the propagation of salient signals to self-referential processing. Simultaneously, the intervention strengthened top-down executive control. These findings suggest that combining tDCS with mindful walking effectively ameliorates DMN-dominant/ECN-recessive imbalance., highlighting its potential as a clinical tool to facilitate mindfulness engagement.