Effects of transcranial direct current stimulation on inhibition-related oscillatory brain activity during an...

Previous studies have shown that transcranial direct current stimulation (tDCS) applied to the dorsolateral prefrontal cortex (dlPFC) can enhance attentional performance and influence emotional processing. However, the neural mechanisms underlying these effects are not fully understood. This study aimed to investigate oscillatory changes following tDCS over the dlPFC, with the hypothesis that anodal stimulation of the right dlPFC would modulate inhibition-related oscillations in the presence of threatening faces compared with left dlPFC stimulation.

Thirty-six healthy participants underwent bilateral tDCS to the dlPFC. One group received anodal tDCS to the right dlPFC and cathodal to the left dlPFC, while the second group received the opposite montage. A control group received sham stimulation. Before and after stimulation, behavioral performance and event-related theta oscillations were recorded during an antisaccade task involving neutral and angry faces.

Compared to the left-dlPFC group, the right-dlPFC group showed lower theta responses at F3 after anodal stimulation, particularly during antisaccade trials with angry faces, which are known to impose higher inhibitory demands due to threat salience. No group differences were found in saccade latencies. These findings suggest that anodal right dlPFC stimulation modulates oscillatory activity related to inhibitory control under emotionally salient conditions.

A decrease in theta oscillations following anodal tDCS over the right dlPFC may indicate enhanced inhibitory control during the processing of threatening stimuli. These results point to a potential role of dlPFC-targeted tDCS in regulating cognitive control and emotional processing, particularly in individuals with difficulties in these domains. However, the directionality and causality of these effects cannot be conclusively established due to limitations of the current study design.