ABSTRACT
Postural responses to transcutaneous galvanic stimulation of the right labyrinth were recorded by means of a stabilograph in normal human subjects in various head positions as well as under the illusion of head and trunk rotation induced by vibration of the gluteus maximum muscle. The direction of the vestibulo-motor response was determined by the position of the head: in a normal head position the body swayed in the frontal plane, whereas with the head turned 90 degrees it moved in the sagittal plane. During the illusory head and trunk 90 degrees rotation the responses were sagittally directed like those recorded in the real head-turned-sideways position. When the vibration did not induce the illusion of the head rotation with respect to the feet, the direction of the postural response was determined by the real head orientation. It is concluded that the spatial perception system is involved in the control of spatially oriented vestibulo-motor responses.
