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

Abstract

Transcranial direct current stimulation (tDCS) is increasingly used to study motor- and non-motor-related functions of the cerebellum. The aim of the present study was to quantitatively review available studies to estimate the efficacy of cerebellar tDCS in altering motor- and cognitive-related behavioral performance in healthy volunteers. The present meta-analysis included 32 sham-controlled studies. Results from random effects modeling of the cumulative effect size demonstrated that anodal and cathodal tDCS to the cerebellum were effective in changing performance. No evidence for polarity-dependent effects of cerebellar tDCS was found. Current findings establish the feasibility to target motor and non-motor-related cerebellar functions with tDCS, but arguably due to anatomical differences between the cerebellum and cerebral cortex, the polarity of tDCS is not predictive of the direction of the behavioral changes in healthy volunteers.

Cortico-Cerebellar Networks Drive Sensorimotor Learning in Speech

“…A more substantial problem with applying our results to a clinical setting might be that, in the case of anodal stimulation to the cerebellum, we observed both facilitation and inhibition of learning. Despite claims to the contrary, anodal stimulation can impair certain behaviours (and cathodal stimulation can improve them) (Ferrucci et al, 2008;Pope and Miall, 2012;Bestmann et al, 2015;Lametti et al, 2016;Oldrati and Schutter, 2017) . Indeed, our understanding of the mechanisms by which tDCS influences behaviour remains largely speculative, and the stimulation-action relationship is likely more complex than is often assumed.…”

Consensus Paper: Cerebellum and Emotion

“…These studies focus primarily on different motor functions such as visuomotor adaptation [16], motor learning [17], or balance control [18], but some also focus on cognitive functions such as probabilistic classification learning [19], verb generation [20], or attentional control [21]. Recently, Oldrati and Schutter [22] published a quantitative review of 32 shamcontrolled studies employing cerebellar tDCS to modulate both motor-and non-motor-related cerebellar functions. They showed that cerebellar tDCS was indeed effective in changing performance, but they could not find the expected polarity-dependent effects as demonstrated in the works of Nitsche and Paulus [6].…”

Functional near-infrared spectroscopy in conjunction with electroencephalography of cerebellar transcranial direct current stimulation responses in the latent neurovascular coupling space – a chronic stroke study

“…We used subject matched age-groups for computational modeling to estimate electric field stimulation for the patients who had no lesion in the cerebellum. However, the differences in individual cerebellar anatomy and residual connectivity can play an essential role in the efficacy of the ctDCS [88], which may have resulted in the inter-subject variability in fNIRS-EEG results. Future clinical studies with a bigger sample size are required for unraveling the systematic effects of the optimized ctDCS for different cerebellar regions using a multivariate GLM.…”