Cognitive effects of transcranial direct current stimulation and virtual environments

Transcranial direct current stimulation (tDCS) involves the introduction of a small amount of current to the participant’s brain to influence brain activity in the stimulated areas. Research using tDCS has involved a wide range of cognitive and affective domains. A limitation to the generalization of these findings to everyday cognitive processes is that these studies often involve simple stimuli that may not reflect the more dynamic cognitive and affective processes found in activities of daily living. To address this issue, a growing number of studies have begun using virtual environments (VE) that include dynamic simulations of everyday activities. Lacking is a quantitative meta-analysis that enhances understanding of the cognitive manipulations resulting from tDCS protocols that include VEs. Searches of electronic databases yielded 756 studies. Thirteen studies (618 subjects) met inclusion criteria. Preliminary results reveal that tDCS produced a statistically significant Hedge’s g of 0.45. The effect for tDCS was statistically significant for both immersive virtual stimuli, g = 0.25, and screen captures from VEs, g = 0.79. Analyses of results relative to cognitive domains revealed that tDCS had the greatest influence on risk assessment, g = 0.67. Small effect sizes were observed for attention and executive functioning, g = 0.21 and hippocampal dependent tasks, g = 0.17. In summary, while tDCS combined with VEs produced medium effects on cognition, the effects were relative to cognitive domain. A potentially promising use of tDCS with VEs may be that of training.