Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that can modulate cortical neuronal excitability through scalp electrodes, thereby potentially enhancing cognitive function. However, to date, no specific stimulation targets have been identified in studies on tDCS for improving cognitive function. Previous research has suggested that the left dorsolateral prefrontal cortex (DLPFC) and parietal-occipital regions (PO) of the human brain may be potential therapeutic targets. Based on this, the present study aims to compare the mechanisms of how tDCS affect working memory by modulating DLPFC and PO regions, providing empirical support for clinical application. According to different stimulation targets, the experiment was divided into DLPFC group, PO group and sham group in this study. A total of 20 participants were recruited to participate in the tDCS regulation trial. Each participant was randomly assigned to receive two types of stimuli, with a minimum interval of 3 days between each stimulus (a total of 40 stimuli). This study designed the "3-back " working memory task paradigm, calculated and analyzed the reaction time (RT) and accuracy (AC) of three groups of subjects in cognitive tasks before and after receiving tDCS regulation. This study collected resting state electroencephalogram (EEG) signals from three groups of subjects before and after regulation, and compared and analyzed the autocorrelation of each brain functional area, the cross-correlation between different brain functional regions, and the corresponding network topology characteristics. The results showed that after regulation, for subjects in the DLPFC group and PO group, the AC increased and RT decreased, with the DLPFC group demonstrating better effects. Additionally, DLPFC stimulation could enhance the autocorrelation and cross-brain connectivity of targets and related brain regions in the theta and beta frequency bands, and improve the clustering coefficient and local efficiency of brain regions in these frequency bands. However, PO stimulation and sham stimulation had no such effects. This study confirms that tDCS stimulation of DLPFC can improve cognitive function by enhancing the network connectivity of brain regions related to the theta and beta frequency bands, providing experimental evidence and theoretical support for the clinical rehabilitation of brain cognitive dysfunction using tDCS.
