Figure 1.

Illustration of the electrical stimulation paradigm. Stimulation was delivered to one vestibular electrode at a time. Patients first received baseline electrical stimulation that consisted of constant amplitude trains of biphasic, cathodic-first pulses (upper-left panel). Baseline stimulation was presented at a fixed pulse rate of 400 pulses per second. Its intensity corresponded to 50% of each electrode's previously measured dynamic range (DR; current range between the vestibular threshold -THRS- and the upper comfortable level -UCL-). Once patients were in “adapted” state, the baseline stimulation could be modulated in amplitude using a signal with a sinusoidal profile (see lower-left panel). The strength (i.e., intensity) of the modulation was kept constant and its frequency was varied between 0.5 and 2 Hz. The right panel shows an example of such an amplitude modulated stimulation signal (blue trace). The envelope of the modulation signal (red dotted lines) has been highlighted for clarity.