ABSTRACT
The postural control mechanisms in the human body while standing include the vision, proprioception, exteroception, and vestibular (Fig. 23.1). Several researchers have even reported auditory or olfactory stimulation as being of significance. 1-3 In research projects, however, visual stimulation will be the most effective of the sensory stimuli, because it can be administered quantitatively. Visual stimulation may disturb a person's equilibrium in a standing posture and result in body instability that elicits a consequent righting reflex, whereas vestibular stimulation acts as a servomotor on body balance with the assistance of vision. 8 Therefore, quantitative visual stimulation can determine bodily stability, which includes the vestibular, proprioceptive, and exteroceptive functions. The most important interaction exists between the visual and vestibular functions. Vestibulo-visual cooperation contributes to an efficient righting reflex. The relationship between the oculomotor and vestibular systems is so strong that their mutual activities will be integrated in the brainstem, and a constant input-output relationship may be obtained.
