The Effects of Transcranial Direct Current Stimulation Versus Electroacupuncture on Working Memory in Healthy Subjects

Objective: Working memory (WM) can influence human thought processes through interactions with perception, long-term memory, and behavior. In recent years, transcranial direct current stimulation (tDCS) and electric acupuncture have been used to improve the performance of WM. Therefore, due to the n-back task as a continuous performance task that is commonly used to measure WM, the aim of this study is to investigate the differences in short-term efficacy between tDCS and electroacupuncture on WM under n-back task paradigm in healthy subjects. Methods: Forty-four college students (age: 23.70 ± 1.52 years; education: 16.93 ± 2.24 years) were recruited as experimental subjects and randomly divided into two groups by a random double-blind two-stage crossover experiment design. Group A received a tDCS intervention followed by at least 1 week of washout period and then the electroacupuncture intervention. Group B had the opposite sequence of interventions. The WM test under the n-back task paradigm was conducted before and after each intervention, and the changes in the accuracy (number of correct responses) and correct response time (RT) before and after the interventions were detected. The data were statistically analyzed using SPSS 24.0 to compare the short-term efficacy of tDCS and electroacupuncture on WM under different tasks. Results: In the 0-back task and 1-back tasks, there was no significant difference in the accuracy or RT before and after the interventions between tDCS and electroacupuncture stimulation. In the 2-back task, there was no significant difference in the accuracy before and after interventions between tDCS and electroacupuncture stimulation. However, there was a significant difference in RT (p < 0.05), which was lower after tDCS than after electroacupuncture in the 2-back task. Conclusion: The results show that tDCS with anodal stimulation on the left dorsolateral prefrontal cortex could increase the RT of the 2-back task performance in comparison with electroacupuncture stimulation of the Baihui (GV20) and Shenting (DU24) acupoints. The present results indicate that tDCS may have greater impact on WM in healthy subjects than electroacupuncture stimulation.