The Journal of Neuroscience, July 1, 2002, 22(13):5734-5740
Sensory Gating for the Initiation of the Swing Phase in Different
Directions of Human Infant Stepping
Marco Y. C.
Pang1 and
Jaynie F.
Yang1, 2
1 Centre for Neuroscience and 2 Department
of Physical Therapy, University of Alberta, Edmonton, Alberta,
Canada T6G 2G4
Humans can make smooth, continuous transitions in walking direction
from forward to backward. Thus, the processing of sensory input must
allow a similar continuum of possibilities. Hip extension and reduced
load are two important conditions that control the transition from the
stance to swing phase during forward stepping in human infants. The
purpose of this study was to determine whether the same factors also
regulate the initiation of the swing phase in other directions of
stepping. Thirty-seven infants between the ages of 5 and 13 months were
studied during supported forward and sideways stepping on a treadmill.
Disturbances were elicited by placing a piece of cardboard under the
foot and pulling the cardboard in different directions. In this way,
the leg was displaced in a particular direction and simultaneously
unloaded. We observed whether the swing phase was immediately initiated
after the application of disturbances in various directions.
Electromyography, vertical ground reaction forces, and hip motion in
frontal and sagittal planes were recorded. The results showed that the
most potent sensory input to initiate the swing phase depends on the
direction of stepping. Although low load was always necessary to
initiate swing for all directions of walking, the preferred hip
position was always one directly opposite the direction of walking. The results indicated the presence of selective gating of sensory input
from the legs as a function of the direction of stepping.
Key words:
human; infants; locomotion; proprioceptive input; sensorimotor control; sensory gating
Copyright © 2002 Society for Neuroscience 0270-6474/02/22135734-07$05.00/0
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