Anodal tDCS applied during multitasking training leads to transferable performance gains

Abstract

Cognitive training can lead to performance improvements that are specific to the tasks trained. Recent research has suggested that transcranial direct current stimulation (tDCS) applied during training of a simple response-selection paradigm can broaden performance benefits to an untrained task. Here we assessed the impact of combined tDCS and training on multitasking, stimulus-response mapping specificity, response-inhibition, and spatial attention performance in a cohort of healthy adults. Participants trained over four days with concurrent tDCS – anodal, cathodal, or sham – applied to the left prefrontal cortex. Immediately prior to, 1 day after, and 2 weeks after training, performance was assessed on the trained multitasking paradigm, an untrained multitasking paradigm, a go/no-go inhibition task, and a visual search task. Training combined with anodal tDCS, compared with training plus cathodal or sham stimulation, enhanced performance for the untrained multitasking paradigm and visual search tasks. By contrast, there were no training benefits for the go/no-go task. Our findings demonstrate that anodal tDCS combined with multitasking training can extend to untrained multitasking paradigms as well as spatial attention, but with no extension to the domain of response inhibition.

The neural basis of multitasking

“…the probability of any given stimulus, given the context of task A ceases to serve as a reasonable model for the probability of a given stimulus, given the context of task B. Multitasking costs remained higher when the covariance between stimulus representations was high (hi), relative to low (lo). The predicted reductions in MT costs look similar to previous observations, for example B) where participants completed a multitasking paradigm over multiple training sessions (taken from (Filmer, Lyons, et al 2017) . Additionally, the observed increase in costs for high relative to low covariances in stimulus representations looks analogous to previous observations that even over thousands of trials, participants take longer to respond to stimuli that potentially share higher covariances (panel C, Irrelevant stimuli) relative to those with lower covariances (Relevant stimuli).…”

Evaluating the Effects of Online tDCS with Emotional n-back Training on Working Memory and Associated Cognitive Abilities

“…However, others have suggested that tDCS, with or without WMT, needs repeated administration to induce long-term potentiation (Alonzo, Brassil, Taylor, Martin, & Loo, 2012;Meinzer et al, 2014), yet others have suggested that tDCS has little effect on cognitive function at all (Horvath, Forte, & Carter, 2015). Within the literature, the strength and duration of current delivery is also varied, but generally kept within 1 milliampere (mA) administered for approximately 5 to 30 minutes with few studies providing stimulation on the upper end of this duration (Clarke, Browning, Hammond, Notebaert, & MacLeod, 2014;Filmer, Lyons, Mattingley, & Dux, 2017;Nitsche et al, 2003;Ruf et al, 2017). If a brief but concentrated tDCS-WMT training paradigm can produce changes in core cognitive capabilities, such an intervention can be easily transported and utilized in a variety of contexts where WM is impacted.…”

Transcranial direct current stimulation interventions for cognition in older adults

“…Interestingly, studies that have combined training and tDCS seem to find little benefit over training alone, which is in contrast to work in younger adults (e.g. Filmer et al, , 2017bLooi et al, 2016;. Nevertheless, the small number of studies here with considerable variability in protocols suggests a potential area for future research.…”

“…Critically, repeated sessions of tDCS have been shown to induce long-term potentiation (LTP) and long-term depression (LTD)-like changes in underlying brain regions in young and older adults, suggesting that stimulation could lead to more substantial alterations in neuroplasticity (Di Lazzaro et al, 2012;. It is largely due to this property that tDCS has received attention as a potential treatment for age-related cognitive decline and multi-tasking paradigms (Filmer, Lyons, Mattingley, & Dux, 2017b) following four days of combined training and tDCS, which persisted at a two-week follow-up. Furthermore, Looi et al (2016) found working memory benefits after two sessions of mathematics training combined with tDCS, which were sustained two months following the intervention.…”

“…tDCS has also been paired with cognitive training protocols in an attempt to facilitate training benefits and transfer of benefits to other domains. For example, studies in our group have administered four days of training on a decision-making or dual-task combined with anodal tDCS to the left PFC, and achieved improvements in untrained visual attention and multi-tasking paradigms (Filmer, Lyons, Mattingley, & Dux, 2017b), which persisted at two week follow-up. In addition, Looi et al (2016) administered two sessions of video-game style mathematics training combined with anodal tDCS to the prefrontal cortices (bilateral) and found working memory benefits both immediately and two months following the intervention.…”