Cerebellar transcranial direct current stimulation for learning a novel split-belt treadmill task: a randomised controlled trial

Abstract

This study aimed to examine the effect of repeated anodal cerebellar transcranial direct current stimulation (ctDcS) on learning a split-belt treadmill task. thirty healthy individuals randomly received three consecutive sessions of active or sham anodal ctDcS during split-belt treadmill training. Motor performance and strides to steady-state performance were evaluated before (baseline), during (adaptation), and after (de-adaptation) the intervention. the outcomes were measured one week later to assess absolute learning and during the intervention to evaluate cumulative, consecutive, and session-specific effects. Data were analysed using linear mixed-effects regression models. During adaptation, there was no significant difference in absolute learning between the groups (p > 0.05). During de-adaptation, a significant difference in absolute learning between the groups (p = 0.03) indicated slower de-adaptation with anodal ctDcS. pre-planned secondary analysis revealed that anodal ctDCS significantly reduced the cumulative (p = 0.01) and consecutive-session effect (p = 0.01) on immediate adaptation. There were significant cumulative (p = 0.02) and session-specific effects (p = 0.003) on immediate de-adaptation. Repeated anodal ctDCS does not enhance motor learning measured during adaptation to a split-belt treadmill task. However, it influences the maintenance of learnt walking patterns, suggesting that it may be beneficial in maintaining therapeutic effects. Cerebellar transcranial direct current stimulation (ctDCS), a non-invasive brain stimulation technique, has the potential to become a neuro-rehabilitation tool to facilitate therapy-induced recovery in people with brain lesions 1,2. Various neuro-physiological studies 3-5 have demonstrated that ctDCS is capable of altering the excitability of the cerebellum, a critical structure in error-driven motor learning 6-8. There is evidence of improved gains in motor performance up to 48 h after a single application of anodal ctDCS 9,10. However, evidence of its ability to induce long-lasting changes in motor performance with multiple sessions of stimulation is limited 11,12. This study aimed to elucidate the effect of three consecutive sessions of anodal ctDCS on motor learning of a novel treadmill walking task in healthy individuals. Motor learning is an internal process associated with practice or experience, which results in the long-lasting acquisition of skilled motor performance 13. To examine the effect of an intervention on motor learning, evaluation of motor performance more than 24 h after the intervention is required 13. This is because the transient effects of the intervention dissipate, but the relatively permanent effects remain at the follow-up evaluation reflecting learning. Such learning is fundamental for acquiring new motor skills and adapting to changing environments in our daily lives. Motor learning is commonly investigated in the laboratory through motor skill and motor adaptation paradigms. Motor skill training paradigms often use novel or compl...

Mini-review: The Role of the Cerebellum in Visuomotor Adaptation

“…For example, Galea et al [46] showed that anodal tDCS over the right cerebellum led to faster adaptation to a visuomotor rotation as evident by rapid reduction of movement errors compared to sham or to anodal tDCS to left M1. Later studies have replicated this finding with the same task [47,48], in older subjects [49], using force field adaptation [50] as well as in other forms of motor skill learning that require adaptation to a visuomotor manipulation [50][51][52][53]. However, recent attempts to replicate the positive effect of cerebellar tDCS on visuomotor adaptation in large groups of subjects were not successful [54][55][56].…”

On Nonlinear Regression for Trends in Split-Belt Treadmill Training

“…The position of reflective markers was captured via nine-cameras at a frame rate of 200 Hz. The data were recorded during the last minute of the baseline phase and throughout the adaptation and the de-adaptation phase [ 61 ]. A MATLAB-based implementation of the Detection and Correction Algorithm (DACA) was utilised for determining the gait events: heel-strikes and toe-offs for each foot [ 62 ].…”

A Single Session of Anodal Cerebellar Transcranial Direct Current Stimulation Does Not Induce Facilitation of Locomotor Consolidation in Patients With Multiple Sclerosis

“…Therefore, we cannot exclude that with only one tDCS session, the effects may have been minimal, where multiple sessions could have allowed for larger and more long-lasting effects of stimulation to manifest. However, a very recent study has evaluated the effects of three consecutive sessions of anodal cerebellar tDCS on motor learning measured during adaptation to a SBT task and found no significant effect compared to sham stimulation in a healthy population (Kumari et al, 2020). This result speaks against the potential benefit of multiple tDCS sessions on motor adaptation and consolidation.…”