Cerebellar transcranial direct current stimulation (cerebellar tDCS) is increasingly used in neurophysiology laboratories, and its use begins in clinical research [1, 2]. The technique consists in delivering for minutes through a surface scalp electrode a weak (1–2 mA) direct current over the cerebellum. The technique is painless, and stimulation can be delivered during any motor or cognitive activity. Research findings (for a review, see [2]) already provide evidence that cerebellar tDCS can induce neurophysiological changes in the cerebello-brain interaction [3–6] and can influence gait adaptation [7], motor learning [8–12] and cognition [13–18] in healthy humans. Preliminary clinical observations suggest that the changes induced by cerebellar tDCS could be clinically useful in patients with various disorders involving cerebellar dysfunction [19, 20].

Though current evidence leaves open possible (transynaptic or antidromic) changes in other brain or brainstem structures, the physiological effects elicited by cerebellar tDCS arise mainly from functional changes in the cerebellum itself. Cerebellar tDCS could interfere with membrane polarisation in Purkinje cells and in other neurons, fibres (mossy fibres and climbing fibres) and glial cells. DC stimulation applied to the cerebellar cortex in the decerebrated cat influences Purkinje and granular cell activity in a polarity-specific manner; while anodal DC (0.1–1 mA) flowing in the dendrite–axonal direction increases tonic neuronal activity, cathodal DC decreases it [21].

Given the technique’s growing popularity among neuroscientists, for the reader approaching cerebellar tDCS for the first time, we believe it to be useful to describe its methodology. This description has a preliminary limitation; however, insofar, most of the critical methodological variables (for instance, stimulation duration and intensity, number of sessions) have been so far empirically set and no systematic studies have yet assessed how they influence the effects elicited by cerebellar tDCS. Throughout the text, we refer to data available in the literature summarized in Table 1.