Article

A reliable and adaptive relationship between action and perception is necessary
for postural control. Our understanding of how this adaptive sensorimotor control
develops during infancy is very limited. This study examines the dynamic
visual-postural relationship during early development.
Twenty healthy infants
were divided into 4 developmental groups (each n=5): sitting onset, standing
alone, walking onset, and 1-year post-walking. During the experiment, the infant
sat independently in a virtual moving-room in which anterior-posterior
oscillations of visual motion were presented using a sum-of-sines technique with
five input frequencies (from 0.12 to 1.24 Hz). Infants were tested in five
conditions that varied in the amplitude of visual motion (from 0 to 8.64 cm).
Gain and phase responses of infants' postural sway were analyzed. Our results
showed that infants, from a few months post-sitting to 1 year post-walking, were
able to control their sitting posture in response to various frequency and
amplitude properties of the visual motion. Infants showed an adult-like
inverted-U pattern for the frequency response to visual inputs with the highest
gain at 0.52 and 0.76 Hz. As the visual motion amplitude increased, the gain
response decreased. For the phase response, an adult-like frequency-dependent
pattern was observed in all amplitude conditions for the experienced walkers.
Newly sitting infants, however, showed variable postural behavior and did not
systemically respond to the visual stimulus. Our results suggest that
visual-postural entrainment and sensory re-weighting are fundamental processes
that are present after a few months post sitting. Sensorimotor refinement during
early postural development may result from the interactions of improved
self-motion control and enhanced perceptual abilities.
CI - Copyright (c) 2016 Elsevier B.V. All rights reserved.

Langue : ANGLAIS