Publication date: Available online 19 October 2018
Source: Gait & Posture
Author(s): Michail Doumas, Theofilos Ch. Valkanidis, Vassilia Hatzitaki
Abstract
Background
Postural control relies on sensory information from visual, vestibular and proprioceptive channels, with proprioception being the key sensory modality in this task. Two well-established ways of manipulating proprioceptive information in postural control are tendon vibration and sway referencing. The aim of the present study was to assess postural adaptation when inaccurate proprioceptive information is introduced using tendon vibration and sway referencing in isolation and combination.
Methods
Seventeen young adults were asked to stand, without vision, for 2 minutes on a fixed surface (Baseline) immediately followed by 3 minutes of bilateral Achilles tendon vibration, sway reference, or combined presentation of the two manipulations (Adaptation) and finally 3 minutes of standing on a fixed surface (Aftereffect).
Results
During adaptation, vibration showed the lowest sway variability, followed by sway reference and the combined condition. Spectral analyses focusing on the dominant frequencies in this task (0-0.4 Hz) showed that in the first half of adaptation sway amplitude was greater when the two manipulations were combined compared with each manipulation alone. However, in the second half differences between sway reference and the combined condition disappeared but differences between vibration and the other two conditions increased.
Conclusion
We interpret these findings primarily as due to a prolonged attenuation in effects of vibration over the course of the adaptation phase and we offer two explanations for this phenomenon. One is a decline in neurotransmitter release from the group Ia terminals and the other is sensory reweighting which down-weights proprioception and up-weights the accurate, vestibular information.
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