Time- but Not Sleep-Dependent Consolidation of tDCS-Enhanced Visuomotor Skills

Abstract

Consolidation of motor skills after training can occur in a time- or sleep-dependent fashion. Recent studies revealed time-dependent consolidation as a common feature of visuomotor tasks. We have previously shown that anodal transcranial direct current stimulation (tDCS) in combination with repeated motor training benefits consolidation by the induction of offline skill gains in a complex visuomotor task, preventing the regular occurrence of skill loss between days. Here, we asked 2 questions: What is the time course of consolidation between days for this task and do exogenously induced offline gains develop as a function of time or overnight sleep? We found that both the development of offline skill loss in sham-stimulated subjects and offline skill gains induced by anodal tDCS critically depend on the passage of time after training, but not on overnight sleep. These findings support the view that tDCS interacts directly with the physiological consolidation process. However, in a control experiment, anodal tDCS applied after the training did not induce skill gains, implying that coapplication of tDCS and training is required to induce offline skill gains, pointing to the initiation of consolidation already during training.

Effects of tDCS on motor learning and memory formation: A consensus and critical position paper

“…This may be particularly important for a technique like tDCS (which may exert its effect through the alteration of thresholds for neuronal discharge (Fritsch et al, 2010)) as observed effects may be highly dependent on the specific context in which it is applied. Currently, the most frequently used tasks to investigate motor skill learning in experimental settings are: (1) sequential finger tapping tasks (SFTT; which can include either implicit or explicit sequence structure) (Ghilardi, Moisello, Silvestri, Ghez, & Krakauer, 2009;Nitsche et al, 2010;Reis et al, 2015;Song & Cohen, 2014); and (2) the sequential visual isometric pinch force task (SVIPT) (Reis et al, 2009). In a sense, these tasks are complimentary in that for the SFTT, the main unit of action is rather trivial for a healthy subject to accomplish (i.e.…”

“…The effects of anodal tDCS on online sequence learning have been a particular area of interest (Amadi, Allman, Johansen-Berg, & Stagg, 2015;Ambrus et al, 2016;Cuypers et al, 2013;Kang & Paik, 2011;Kantak, Mummidisetty, & Stinear, 2012;Karok & Witney, 2013; M. F. Kuo et al, 2008;Nitsche et al, 2010;Nitsche et al, 2003;Reis et al, 2015;Reis et al, 2009;Stagg, Jayaram, et al, 2011;Tecchio et al, 2010;Vines, Cerruti, & Schlaug, 2008;Wade & Hammond, 2015). In an initial study, Nitsche and colleagues (2003) showed that anodal tDCS applied over M1 concurrently with training improved online implicit learning of a motor sequence, while stimulation applied to PMd, DMPFC and DLPFC did not .…”

“…Several studies, a majority of which have focused on sequence learning, have investigated offline motor skill learning and retention over multiple (typically at least three) days of training (Table 2) (Cantarero et al, 2015;Naros et al, 2016;Reis et al, 2015;Reis et al, 2009;Saucedo-Marquez, Zhang, Swinnen, Meesen, & Wenderoth, 2013;Schambra et al, 2011;Waters-Metenier et al, 2014). Reis and colleagues (2009) found that anodal tDCS applied to M1 concurrently with training over five consecutive days resulted in significant enhancement of offline skill gains and retention compared with sham in the sequential visual isometric pinchforce task (SVIPT) (Reis et al, 2009).…”

“…Several recommendations from that paper have been advanced in the literature. For example, many studies have utilized multi-session rather than single-session tDCS application (Hashemirad et al, 2016), greater emphasis has been placed on monitoring long-term effects of tDCS on motor learning (Hashemirad et al, 2016), evidence of dissociation of tDCS effects applied to distinct brain regions on different stages of motor learning (Galea et al, 2011;Reis et al, 2015;Wymbs, Bastian, & Celnik, 2016) has begun to emerge, and mechanisms underlying tDCS effects are starting to be elucidated (Fritsch et al, 2010; H. I. Kuo et al, 2013; M. F. Kuo et al, 2008;Lang, Nitsche, Sommer, Tergau, & Paulus, 2003;Stagg, Bachtiar, & Johansen-Berg, 2011).…”

Stimulating cognition in schizophrenia: A controlled pilot study of the effects of prefrontal transcranial direct current stimulation upon memory and learning

“…However, we anticipated increased activation beneath the anode during WM and EF in the real tDCS group; in the former task activation change would correlate with task performance after consolidation [37,38]. At the system level we expected reduced activation in the task relevant WM and EF networks in the real tDCS group [30]; the bilateral parietal cortex and ACC respectively [39][40][41][42][43].…”