Relative contributions of visual and vestibular information on the trajectory of human gait
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Seven healthy individuals were recruited to examine the interaction between visual and vestibular information on locomotor trajectory during walking. Subjects wore goggles that either contained a clear lens or a prism that displaced the visual scene either 20° to the left or right. A 5-s bipolar, binaural galvanic stimulus (GVS) was also applied at three times the subject's individual threshold (ranged between 1.2 to 1.5 mA). Subjects stood with their eyes closed and walked forward at a casual pace. At first heel contact, subjects opened their eyes and triggered the galvanic stimulus by foot switches positioned underneath a board. Reflective markers were placed bilaterally on the shoulders as the walking trajectory was captured using a camera mounted on the ceiling above the testing area. Twelve conditions were randomly assigned that combined four visual conditions (eyes closed, eyes open, left prism, right prism) and three GVS conditions (no GVS, GVS anode left, GVS anode right). As subjects walked forward, there was a tendency to deviate in the direction of the prisms. During GVS trials, subjects deviated towards the anode while walking, with the greatest deviations occurring with the eyes closed. However, when GVS was presented with the prisms, subjects always deviated to the side of the prisms, regardless of the position of the anode. Furthermore, the visual-vestibular conditions produced a larger lateral deviation than those observed in the prisms-only trials. This suggests that the nervous system examines the sensory inputs and takes into account the most reliable and relevant sensory input.
KeywordsGalvanic vestibular stimulation Displacing prisms Vision Vestibular system Gait
The authors would like to thank P. Nagelkerke for his technical contributions to this study. This research was supported by the Natural Sciences and Engineering Research Council of Canada grants to J.T.I., I.M.F, and to R.C.
- Camis M, Creed RS (1930) The physiology of the vestibular apparatus. Clarendon, Oxford, UKGoogle Scholar
- Dichgans J, Mauritz KH, Allum JH, Brandt T (1976) Postural sway in normals and atactic patients: analysis of the stabilizing and destabilizing effects of vision. Agressologie 17:15–24Google Scholar
- Fitzpatrick RC, Wardman DL, Taylor JL (1999) Effects of galvanic vestibular stimulation during human walking. J Physiol 517:931–939Google Scholar
- Gibson JJ (1958) Visually controlled locomotion and visual orientation in animals. Br J Psychol 49:182–194Google Scholar
- Glasauer S, Amorim MA, Vitte E, Berthoz A (1994) Goal directed linear locomotion in normal and labyrinthine defective subjects. Exp Brain Res 98:323–335Google Scholar
- Horak FB, Macpherson JM (1996) Postural orientation and equilibrium. In: Rowell LB, Shepherd JT (eds) Handbook of physiology, sect 12: exercise: regulation and integration of multiple systems. Oxford University Press, New York, pp 255–292Google Scholar
- Lee DN, Young DS (1986) Gearing action to the environment. Exp Brain Res Ser 15:217–230Google Scholar
- Rogers BJ, Dalton C (1999) The role of (i) perceived direction and (ii) optic flow in the control of locomotion and for estimating the point of impact. Invest Ophthalmol Vis Sci 40:S764Google Scholar
- Rossignol S (1996) Visuomotor regulation of locomotion. Can J Physiol Pharmacol 74:418–425Google Scholar
- Wilson VJ, Melvill Jones G (1979) Mammalian vestibular physiology. Plenum, New YorkGoogle Scholar