Promoting the acquisition of independent mobility by exploiting the coupling between vision and early stepping

• In Event: 1-203 - The development of visual-motor integration during activities of daily living: From research to translation

Integrative Statement

Introduction
Independent locomotion is one of the most widely utilized, important, and extensively-studied skills within the repertoire of human behavior. Surprisingly, however, experimental findings pertaining to the earliest form of locomotion, neonatal stepping, are only now being incorporated into clinical practice. This situation is disappointing because recent discoveries suggest that a variety of factors can be manipulated to improve the odds of acquiring independent mobility for the millions of children worldwide who suffer from a locomotor disability. One factor that holds promise for improving locomotor interventions is the coupling between vision and early stepping. Researchers have shown that stepping is facilitated when newborns are exposed to a visual treadmill – a pattern of optic flow that moves beneath the newborns’ feet, specifying forward and backward displacement. The purpose of this presentation is to review our research on the early coupling between vision and stepping, including hitherto unpublished data from our lab and research from other labs in which optic flow has been used to facilitate treadmill stepping in older infants, and describe how this coupling can be exploited to enhance clinical interventions for infants with locomotor disabilities.
Hypotheses
The main hypotheses are that optic flow can be used to: 1) initiate and enhance stepping in very young infants, and 2) accelerate the acquisition of independent mobility in infants with locomotor disabilities, or at risk for developmental delays, who are exposed to locomotor interventions.
Methods
Several studies are presented, each with slightly different methods, involving over 150 newborns aged between 2 and 3 days. However, in each study newborns are exposed to optic flows specifying forward and backward translation that are back-projected onto a solid rear projection screen or a pediatric mattress. The optic flow conditions are compared to conditions in which a black and white static pattern or a grey light is statically projected onto the surfaces or the optic flow moves randomly. The infants are tested in either the upright position suspended above the surfaces (air stepping) or supported on top of the surfaces (tactile stepping), or in the prone position (crawling). Each trial lasts one minute and the dependent variables are the number of steps and the kinematic characteristics of the steps.
Results
The results show quite clearly that the optic flow conditions generate more stepping and more mature-looking stepping than the non-optic flow conditions. Moreover, this visuo-locomotor coupling is apparent during crawling and with and without tactile stimulation from the surface. Interestingly, the step kinematics look very similar regardless of whether the infant is air stepping, tactile stepping or crawling. In addition, there is evidence that the locomotor patterns are quadrupedally organized even when the infant is tested in the upright position.
Discussion
We use these findings and findings from other research teams to argue that treadmill, but also air stepping or crawling, training interventions can be enhanced if training commences at birth and mimics the ecological context of natural locomotion as much as possible, especially by the inclusion of optic flow during stepping.

Authors

• David I Anderson, San Francisco State University
  Presenting Author

• Marianne Barbu-Roth, Université Paris Descartes - CNRS
  Non-Presenting Author