Cathodal Transcranial Direct Current Stimulation (tDCS) to the Right Cerebellar Hemisphere Affects Motor Adaptation During Gait

Abstract

The cerebellum appears to play a key role in the development of internal rules that allow fast, predictive adjustments to novel stimuli. This is crucial for adaptive motor processes, such as those involved in walking, where cerebellar dysfunction has been found to increase variability in gait parameters. Motor adaptation is a process that results in a progressive reduction in errors as movements are adjusted to meet demands, and within the cerebellum, this seems to be localised primarily within the right hemisphere. To examine the role of the right cerebellar hemisphere in adaptive gait, cathodal transcranial direct current stimulation (tDCS) was administered to the right cerebellar hemisphere of 14 healthy adults in a randomised, double-blind, crossover study. Adaptation to a series of distinct spatial and temporal templates was assessed across tDCS condition via a pressure-sensitive gait mat (ProtoKinetics Zeno walkway), on which participants walked with an induced 'limp' at a non-preferred pace. Variability was assessed across key spatial-temporal gait parameters. It was hypothesised that cathodal tDCS to the right cerebellar hemisphere would disrupt adaptation to the templates, reflected in a failure to reduce variability following stimulation. In partial support, adaptation was disrupted following tDCS on one of the four spatial-temporal templates used. However, there was no evidence for general effects on either the spatial or temporal domain. This suggests, under specific conditions, a coupling of spatial and temporal processing in the right cerebellar hemisphere and highlights the potential importance of task complexity in cerebellar function.

Targeting the Human Cerebellum with Transcranial Direct Current Stimulation to Modulate Behavior: a Meta-Analysis

“…Table 1 shows an overview of the main characteristics of the selected studies. Of these 32 studies, 15 studies applied both anodal and cathodal stimulation (ID: 4, 10, 14, 19, 21, 22, 24, 27, 28, 29, 31, and 32) [ 17 , 23 , 27 , 30 , 32 , 34 – 36 , 39 – 41 , 43 , 44 ], 14 anodal (ID 1, 5, 6, 7, 8, 11, 12, 13, 15, 16, 18, 20, 23, and 30) [ 14 , 18 – 21 , 24 – 26 , 29 , 31 , 33 , 42 , 45 ], and three cathodal tDCS (ID: 3, 9, and 26) [ 16 , 22 , 38 ] (Table 1 ). In study 2 [ 15 ] were reported three experiments, each one comparing anodal and cathodal stimulation.…”

The effects of transcranial direct current stimulation on corticospinal and cortico-cortical excitability and response variability: conventional versus high-definition montages

“…Intra-individual variability was measured by single-pulse MEP standardised z-value SDs as previously utilised (Fernandez et al, 2017;Pellegrini et al, 2018c). For each participant (…”

“…The current quantifying technique for intra-individual variability have only been used on a number of occasions (Fernandez et al, 2017;Pellegrini et al, 2018c). Calculating the SDs from standardised data (z-scores) can be considered a robust method of quantifying intra-individual variability for a given sample of individuals.…”

Effectiveness of cathodal tDCS of the primary motor or sensory cortex in migraine: A randomized controlled trial

“…Fourth, S 1 and M 1 are identified as a part of pain-related neuromatrix, and therefore applying c-tDCS to S 1 or M 1 can reduce brain hyperexcitability and lower sensory and pain thresholds [51]. However, evidence on the relative effectiveness of previous tDCS protocols is scant and inconclusive, largely due to methodological limitations such as sample size, session design, randomization, lack of a control group, and insufficiency or absence of follow-up [38,52,53]. Informed by the above debate and previous observations [54e56], we hypothesized that applying c-tDCS to the right M 1 or S 1 can lessen pain intensity, duration, and frequency in a migraine brain.…”