Abstract
Visual working memory (VWM) is critical for guiding goal-directed behavior across interruptions such as saccades. Currently, training efforts aimed at improving VWM are expanding to include the use of non-invasive brain stimulation, such as transcranial direct current stimulation (tDCS). One challenge is that the mechanism underlying training and tDCS linked VWM improvements remains unclear. Here, participants completed four training sessions on a challenging VWM task while concurrently receiving tDCS to right frontoparietal sites. Participants were randomly assigned to either the anodal tDCS or sham group. Before and after training, participants performed the VWM task while undergoing high-density electroencephalography (HD-EEG). The behavioral data revealed a significant session (pre, post) x tDCS group (anodal, sham) interaction revealing greater improvement in the anodal tDCS group compared to the sham group, F(1,22)=5.01, p< 0.05. This result replicates findings showing that tDCS enhances training effects. To investigate the neural correlates of this effect, we examined the HD-EEG data. Specifically, increases in phase synchrony in the 4-10Hz frequency range are related to enhanced VWM performance. Using the right prefrontal stimulation site as a seed electrode and a nonparametric randomization test, we found a significant session x tDCS group interaction for a cluster of posterior electrode sites, p< 0.05. Follow-up tests illustrated that after training, frontal-posterior phase synchrony increased in the anodal group significantly, p=0.05, whereas the sham group showed no difference. These results confirm the behavioral benefits of adding anodal tDCS to VWM training paradigms and indicate that this benefit is likely due to increased phase synchrony between frontal and posterior brain regions.
Meeting abstract presented at VSS 2016