Effects of prefrontal anodal transcranial direct current stimulation on working-memory and reaction time

Transcranial direct current stimulation (tDCS) has proven to be a useful tool in the scientific research community, particularly for clinical investigation purposes. Neuroimaging studies indicate that there is a connection between the prefrontal cortex (PFC) and working memory (WM), as well as between the primary motor cortex and reaction time (RT). Thus, our goal was to evaluate the effect of anodal stimulation of the PFC, with respect to WM and RT. We tested 20 healthy subjects randomized into two groups - half received active stimulation and the other half sham stimulation. Participants underwent two stimulation sessions of 10 minutes each, separated by a 10-minute interval for rest. The task was performed during the stimulation periods, and consisted in the display of a list of words for the subject to read and memorize. Afterwards, a new list was shown and the subject was asked to to press a key when a repeated word appeared. A current of 1 mA was delivered via a foc.us gamer headset. After both stimulations, the participants answered an Adverse Effects Questionnaire. Statistical tests were performed to compare the accuracy, error rate, and reaction time values for active vs. sham and first vs. second stimulations. The results obtained led us to infer that there were no significant improvements in the performance of the active group in comparison with the sham group, in terms of WM and overall RT values. However, RT data analysis indicated that active simulation subjects showed significantly lower values when compared to the sham group, only for the first stimulation period. Due to emerging technological advances, the videogame industry has started to invest in the commercialization of products that promise to enhance neural functions and, thus, improve gamers' performance. The results obtained provide evidence of the importance of testing such commercial devices. The scientific community should have an active role in the validation of these claims.