Visual motion direction evoked potentials are direction specifically influenced by concurrent vestibular stimulation

We investigated the influence of vestibular stimulation on visual motion-direction perception using electrophysiological recordings. Visual motion-direction evoked potentials decreased in area during the rotation of subjects about their vertical z-axis, when visual and vestibular motion directions were incongruous (visual and vestibular stimulation in the same directions). Visual pattern onset evoked potentials, however, remained unaffected by vestibular stimulation. For rotations about the interaural y-axis, decreased area of visual-direction evoked potentials was found for both congruous and incongruous combinations of visual and vestibular stimulation. The results are in accordance with previous psychophysically obtained data and discussed in terms of postnatal development and neurophysiological optimization processes. An interaction model focused on reciprocal inhibition of the middle temporal visual (MT) area and the medial superior temporal (MST) area is presented.