Electrocortical therapy for motion sickness

Given a sufficiently provocative stimulus, almost everyone can be made motion sick, with approximately one-third experiencing significant symptoms on long bus trips, on ships, or in light aircraft. Current countermeasures are either behavioral or pharmacologic. Behavioral measures include habituation/desensitization treatment protocols as well as positioning the head in alignment with the direction of the gravito-inertial force and maintaining a stable horizontal reference frame. Pharmacologic measures include antimuscarinics, H1 antihistamines, and sympathomimetics, which all detrimentally impact upon cognitive function, rendering them inappropriate for occupational use. All current therapies are only partially effective. Since a functioning vestibular system is critical to the development of motion sickness, we proposed that suppressing vestibular activity could increase tolerance to nauseogenic motion stimuli. We previously showed that application of transcranial direct current stimulation (tDCS), specifically unipolar cathodal stimulation over the left parietal cortex, results in suppression of the vestibular system. Herein, we assessed whether such suppression of vestibular activity using tDCS in normal controls may alleviate motion sickness.