Fig. 1.

(A) tDCS montage implemented to induce vestibular suppression, as previously described in Arshad et al. (2014b). Unipolar left cathodal stimulation was applied for a duration of 15 min with a current of 1.5 Ma. The cathode electrode was applied over left P3 (international 10–20 system for EEG electrode placement); electrode placement area 25 cm². The reference electrode was always placed on the ipsilateral shoulder. (B) Illustrates the effects of left cathodal tDCS upon vestibular nystagmus. In the left panel (black trace) we show the raw trace depicting the vestibular nystagmus elicited during right (upper trace) and left (lower trace) ear cold water caloric irrigations. Right ear cold irrigations induce a left-beating vestibular nystagmus (downward deflection of the fast phase) whereas left ear cold irrigations induce a right-beating vestibular nystagmus (upward deflection of the fast phase. Note the marked suppression of vestibular nystagmus as shown in the right panel (red trace; shown for an individual subject) following left hemisphere inhibition for both right and left ear cold water irrigations. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)