Postural after-effects of stepping on an inclined surface.
In previous studies, blindfolded, healthy subjects exhibited an after-effect of leaning while standing on a horizontal surface after a period of standing on an inclined surface. We investigated whether this kinesthetic after-effect would transfer from one task to another by asking blindfolded subjects to stand on a horizontal surface after stepping-in-place on an incline. Results showed that all subjects demonstrated a forward trunk leaning after-effect lasting from half a minute to over 6 min after stepping on a 10 degrees -toes-up incline for 2.5 min. For 5/7 subjects, the amplitude of the leaning after-effect was very similar following stepping or standing on the inclined surface. The similarity of the post-incline lean between the standing and stepping conditions suggests a common underlying mechanism for the after-effect following standing and walking on a gradient and suggests that prolonged maintenance of a constant ankle or leg posture is not a prerequisite condition for the after-effect. The transfer of a postural effect built-up during a locomotor task to a postural after-effect during a standing task is consistent with a central adaptive mechanism that adjusts the surface-referenced set point for whole body postural orientation for both gait and posture.
Kluzik
JoAnn
J
Neurological Sciences Institute, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006-3499, USA. kluzikj@bu.edu
Horak
Fay B
FB
Peterka
Robert J
RJ
D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007088:Illusions / Q000502:physiology*; D007596:Joints / Q000294:innervation / Q000502:physiology; D007699:Kinesthesis / Q000502:physiology; D008124:Locomotion / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D009949:Orientation / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011434:Proprioception / Q000502:physiology; D016138:Walking / Q000502:physiology