Application of anodal tDCS at primary motor cortex immediately after practice of a motor sequence does not improve offline gain

Abstract

Tecchio et al. (J Neurophysiology 104: 1134-1140 reported that the application of anodal tDCS at primary motor cortex (M1) immediately after practice of a procedural motor skill enhanced consolidation, which in turn improved offline gain. Tecchio et al. noted, however, that this study did not account for known after-effects associated with this form of non-invasive stimulation. The present study was designed to explicitly reevaluate Tecchio et al.'s claim. As in the original study, individuals experienced either anodal or sham stimulation at M1 after practice of a serial reaction time task (SRTT) followed by test trials 15-min later. Two additional novel conditions experienced the test trials after 120-min rather than 15-min thus allowing potential stimulation after-effects to dissipate. The expectation was that if anodal stimulation influences post-practice consolidation leading to offline gain, this effect would be present not only at 15-min but also after 120-min. In agreement with the working hypothesis, findings revealed offline gain at both 15-min and the longer 2-h time period. Unexpectedly, we found no interaction between real and sham conditions. The lack of difference between Real and Sham effects weakens confidence in the potential of post-practice tDCS for consolidation enhancement, while it is more consistent with other claims that decoupling practice and anodal tDCS stimulation in time can reduce the effectiveness of exogenous stimulation for procedural skill gain.

Timing-specific effects of single-session M1 anodal tDCS on motor sequence retention in healthy older adults

“…The current acquisition and immediate retention findings are in line with a number of studies reporting no significant beneficial effects (Chen et al, 2020;Lum et al, 2018;Mooney et al, 2019;Sobierajewicz et al, 2018). However, other studies reporting statistically significant beneficial effects of M1 anodal tDCS on explicit sequence acquisition (Cuypers et al, 2013;Saucedo Marquez et al, 2013;Stagg et al, 2011;Zimerman et al, 2013) and consolidation (Rumpf et al, 2017;Tecchio et al, 2010), pointing to the heterogeneity and equivocality of evidence.…”

Effects of Transcranial Direct Current Stimulation Combined With Physical Training on the Excitability of the Motor Cortex, Physical Performance, and Motor Learning: A Systematic Review

“…Fifteen studies implemented a double-blinded design (Vines et al, 2008;Reis et al, 2009Reis et al, , 2013Williams et al, 2010;Kang and Paik, 2011;Thirugnanasambandam et al, 2011;Goodwill et al, 2013;Hendy and Kidgell, 2013;Kim and Ko, 2013;Fujimoto et al, 2014;Steiner et al, 2016;Rumpf et al, 2017;Baltar et al, 2018;Yosephi et al, 2018;Jafarzadeh et al, 2019), in which both the study personnel and participants were not aware of the types of intervention. Five studies used a single-blinded design (Stagg et al, 2011;Naros et al, 2016;Zandvliet et al, 2018;Bruce et al, 2020;Tseng et al, 2020), and the blinding was not reported in other four studies (Karok and Witney, 2013;Looi et al, 2016;Washabaugh et al, 2016;Chen et al, 2020).…”

“…The total number of recruited participants was 784 (462 males and 322 females, age range: 18-80 years). For the design of tDCS, 19 studies used tDCS to target the M1 (Vines et al, 2008;Reis et al, 2009Reis et al, , 2013Williams et al, 2010;Kang and Paik, 2011;Stagg et al, 2011;Thirugnanasambandam et al, 2011;Goodwill et al, 2013;Hendy and Kidgell, 2013;Karok and Witney, 2013;Kim and Ko, 2013;Naros et al, 2016;Washabaugh et al, 2016;Rumpf et al, 2017;Baltar et al, 2018;Jafarzadeh et al, 2019;Bruce et al, 2020;Chen et al, 2020;Tseng et al, 2020), two studies targeted the cerebellum (Steiner et al, 2016;Zandvliet et al, 2018), one study targeted both the M1 and the cerebellum (Yosephi et al, 2018), one study targeted the primary somatosensory cortex (Fujimoto et al, 2014), and one study targeted the dorsolateral prefrontal cortex (Looi et al, 2016). The current intensities of tDCS were between 1.5 and 2 mA, and the duration of each stimulation session was between 15 to 20 min.…”

“…The size of the electrodes was between 35 and 40 cm 2 . Most studies used sham protocol as the control, in which the current was delivered only during the initial period of each session (i.e., the first 15 to 30 s) and then turned off (Vines et al, 2008;Reis et al, 2009Reis et al, , 2013Williams et al, 2010;Kang and Paik, 2011;Stagg et al, 2011;Thirugnanasambandam et al, 2011;Goodwill et al, 2013;Hendy and Kidgell, 2013;Karok and Witney, 2013;Kim and Ko, 2013;Fujimoto et al, 2014;Looi et al, 2016;Naros et al, 2016;Steiner et al, 2016;Washabaugh et al, 2016;Rumpf et al, 2017;Baltar et al, 2018;Yosephi et al, 2018;Zandvliet et al, 2018;Jafarzadeh et al, 2019;Chen et al, 2020;Tseng et al, 2020); One study used the sham protocol that delivered current during the initial 120 s (Bruce et al, 2020). Different timing of applying tDCS was used.…”

“…Different timing of applying tDCS was used. Two studies applied tDCS before physical training (Thirugnanasambandam et al, 2011;Baltar et al, 2018), and two studies conducted tDCS after physical training (Rumpf et al, 2017;Chen et al, 2020); The other 20 studies applied tDCS during the physical training (Vines et al, 2008;Reis et al, 2009Reis et al, , 2013Williams et al, 2010;Kang and Paik, 2011;Stagg et al, 2011;Goodwill et al, 2013;Hendy and Kidgell, 2013;Karok and Witney, 2013;Kim and Ko, 2013;Fujimoto et al, 2014;Looi et al, 2016;Naros et al, 2016;Steiner et al, 2016;Washabaugh et al, 2016;Yosephi et al, 2018;Zandvliet et al, 2018;Jafarzadeh et al, 2019;Bruce et al, 2020;Tseng et al, 2020).…”