COMBINING WORKING MEMORY TRAINING AND NON-INVASIVE BRAIN STIMULATION TO ENHANCE THE EFFECTS OF TRAINING AND TRANSFER

Abstract

Studies attempting to increase working memory (WM) capacity show promise in enhancing related cognitive functions (see Morrison & Chein, 2011 for a recent review), but have also raised criticism in the broader scientific community given the scattered findings produced by these studies (Morrison & Chein, 2011; Shipstead, Redick, & Engle, 2010, 2012). Non-invasive brain stimulation, in particular transcranial direct current stimulation, has been shown to enhance WM performance in a single session (Fregni, et al., 2005) as well as learning over time in other cognitive domains (Iuculano & Cohen Kadosh, 2013; Reis, et al., 2009). However, the extent to which tDCS might enhance learning on a WM training regime, and the extent to which learning gains might transfer outside of the training task remain unknown. To this end, participants engaged in an adaptive WM training task (previously utilized in Chein & Morrison, 2010; Richmond, Morrison, Chein, & Olson, 2011) for 10 sessions over two weeks, concurrent with either active or sham stimulation of dorsolateral prefrontal cortex. Before and after training, a battery of tests tapping domains known to relate to WM abilities was administered. Results show that tDCS reliably enhanced learning on the training task, particularly in the verbal domain. Furthermore, tDCS was shown to enhance transfer to other untrained WM tasks. These results lend support to the idea that tDCS might bolster training and transfer gains in populations with compromised WM abilities.