A Shocking lack of Difference: Noninvasive Brain Stimulation in Verbal and Spatial Working Memory

Enhancing working memory through brain stimulation can contribute to the neuroergonomic goal of improving cognitive functioning at work and in everyday life. Imaging and lesion studies suggest that verbal and spatial working memory processing may be controlled in separate brain regions. Specifically, verbal working memory has been associated with the left dorsolateral prefrontal cortex (DLPFC) and spatial working memory with the right DLPFC. The current study used noninvasive brain stimulation to further examine this cortical dissociation between verbal and spatial working memory. We administered 2mA or 0.1mA of anodal transcranial direct current stimulation (tDCS) to the left and right DLPFC while participants performed verbal and spatial working memory tasks. Contrary to our initial hypotheses, stimulation of the left DLPFC improved spatial working memory but not verbal working memory. Furthermore, stimulation of right DLPFC did not affect verbal or spatial working memory.