Motor Task-Dependent Dissociated Effects of Transcranial Random Noise Stimulation in a Finger-Tapping Task Versus a Go/No-Go Task on Corticospinal Excitability and Task Performance

Abstract

Background and Objective: Transcranial random noise stimulation (tRNS) is an emerging non-invasive brain stimulation technique to modulate brain function, with previous studies highlighting its considerable benefits in therapeutic stimulation of the motor system. However, high variability of results and bidirectional task-dependent effects limit more widespread clinical application. Task dependency largely results from a lack of understanding of the interaction between externally applied tRNS and the endogenous state of neural activity during stimulation. Hence, the aim of this study was to investigate the task dependency of tRNS-induced neuromodulation in the motor system using a finger-tapping task (FT) versus a go/no-go task (GNG). We hypothesized that the tasks would modulate tRNS’ effects on corticospinal excitability (CSE) and task performance in opposite directions. Methods: Thirty healthy subjects received 10 min of tRNS of the dominant primary motor cortex in a double-blind, sham-controlled study design. tRNS was applied during two well-established tasks tied to diverging brain states. Accordingly, participants were randomly assigned to two equally-sized groups: the first group performed a simple motor training task (FT task), known primarily to increase CSE, while the second group performed an inhibitory control task (go/no-go task) associated with inhibition of CSE. To establish task-dependent effects of tRNS, CSE was evaluated prior to- and after stimulation with navigated transcranial magnetic stimulation. Results: In an ‘activating’ motor task, tRNS during FT significantly facilitated CSE. FT task performance improvements, shown by training-related reductions in intertap intervals and increased number of finger taps, were similar for both tRNS and sham stimulation. In an ‘inhibitory’ motor task, tRNS during GNG left CSE unchanged while inhibitory control was enhanced as shown by slowed reaction times and enhanced task accuracy during and after stimulation. Conclusion: We provide evidence that tRNS-induced neuromodulatory effects are task-dependent and that resulting enhancements are specific to the underlying task-dependent brain state. While mechanisms underlying this effect require further investigation, these findings highlight the potential of tRNS in enhancing task-dependent brain states to modulate human behavior.

Transcranial Random Noise Stimulation Modulates Neural Processing of Sensory and Motor Circuits, from Potential Cellular Mechanisms to Behavior: A Scoping Review

“…For example, the after-effects following tRNS were suggested to vary depending on interindividual differences such as age ( Fertonani et al, 2019 ) or a person’s susceptibility to placebo effects ( Kortuem et al, 2019 ), but probably independent of the BDNF gene polymorphism ( Antal et al, 2010 ). Long-term modulation of CSE with tRNS was suggested to be task-dependent and specific to the underlying brain state ( Chaieb et al, 2009 ; Saiote et al, 2013 ; Jooss et al, 2019 ; Qi et al, 2019 ). However, many of these potential participant-specific determinants still await replication.…”

Stochastic Resonance Reduces Sway and Gait Variability in Individuals With Unilateral Transtibial Amputation: A Pilot Study

“…This concept has fueled decades of research involving auditory, haptic, and visual perception (Lugo et al, 2008;Kurita et al, 2013;Krauss et al, 2016;Itzcovich et al, 2017;Pacchierotti et al, 2017). For example, the addition of noise reduces reaction times compared to baseline when applied as transcranial electrical stimulation of the motor cortex (Jooss et al, 2019) and also enhances actionobservation task performance and improves three-dimensional perception (Ditzinger et al, 2000;Sasaki et al, 2006). The application of stochastic noise to the wrist increases detection rates of delayed visual stimuli (Nobusako et al, 2018).…”

Modulation of impulsive behaviours using transcranial random noise stimulation

“…However, another study found a decrease in go-trial reaction times after repeated sessions of tRNS on the DLPFC [6]. Furthermore, 10 minutes of tRNS over the dominant primary motor cortex led to slowed reaction times and enhanced task accuracy in the GNG task during and after stimulation [7].…”