Effect of ageing on the ability to adapt to a visual distortion during walking.
Degradation of major sensory systems such as proprioception, the vestibular system and vision may be a factor that contributes to the decline in walking stability in older people. In the present study this was examined by introducing a visual distortion by means of prism glasses shifting subject's view 10 degrees to the right while subjects walked towards a target (exposure condition). Shifting the view while walking towards a target will cause subjects to alter their heading in such a way that their walking trajectory describes a curvilinear path. It was expected that older people, when compared to young people, would have greater difficulty adjusting their heading and would show a greater decrease in heading stability, quantified by means of the standard deviation of the lateral position (SDLP). This was indeed the case. When performance in a pre- and post-exposure condition, in which subjects walked without prism glasses, were compared to each other, older people (O group) showed a greater decrease in heading stability than young people (Y group) and middle aged people (M group). Furthermore, it appeared that during the exposure condition adaptation effects were present in the Y and M group, which were absent in the O group. It is discussed that this adaptation is a form of realignment of the proprioceptive and visual system. The absence of realignment in the O group is argued to be caused by degradation of the proprioceptive system, which results in a lowering of the proprioceptive bias of vision.
Huitema
Rients B
RB
Centre for Rehabilitation, University Hospital Groningen, P.O. Box 30.001, 9700 RB Groningen, The Netherlands. r.b.huitema@ppsw.rug.nl
Brouwer
Wiebo H
WH
Mulder
Theo
T
Dekker
Rienk
R
Hof
At L
AL
Postema
Klaas
K
D000222:Adaptation, Physiological; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010469:Perceptual Distortion / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D016138:Walking / Q000502:physiology*