Abstracts Category : Other

The effects of sensory stimulation and arousal on stepping in newborns

by Kim Siekerman

Humans produce step-like movements from birth. Stepping has been successfully utilisedin treadmill training for infants at risk of developmental delay. Previousstudies examining optimal training contexts focused on infants from one month ofage: a knowledge gap exists for newborn stepping. This thesis explored stepping inthree-day-old newborns and investigated whether tactile-proprioceptive and visualstimuli can improve stepping, whilst also controlling for and examining the effects ofarousal. Experiment 1 examined if treadmill stimulation alone would improve stepping.Twenty-one newborns were supported, in four one-minute sessions, on a static ormoving treadmill. In Experiment 2, 20 newborns were supported over a frictionenhancedtreadmill with four different optic flow conditions: no optic flow, opticflow moving congruent or faster than the treadmill, or in random directions. Videofootage, three-dimensional kinematic data (Experiment 2) and electromyography wererecorded. Treadmill movement stimulated forward steps but not vertical flexionextensioncycles. Cycle durations and muscle burst lengths decreased on the movingtreadmill, without showing a linear relationship with treadmill speed. Optic flow onthe moving treadmill did not affect step rate or coordination, although random opticflow increased pump rate, inter-joint coupling and hip extension. Fastest optic flowdeactivated muscles during the stance phase. Arousal improved step rate, swing andstance definition and interlimb alternation in Experiment 1. In Experiment 2, arousalincreased hip extension, inter-joint coupling and muscle activation ratio, withoutchanging temporal and spatial muscle patterns. Improved belt friction may havecaused the differences between experiments. In summary, newborns tolerated steppingon the treadmill and with optic flow. Step rate, coordination, kinematics andneuromuscular behaviour were highly variable but could be modified by tactileproprioceptiveand visual stimulation. Arousal universally stimulated stepping, likelythrough increased muscular activity. Findings support the use of treadmill training frombirth, although long term effects require further investigation.Advisors/Committee Members: Donnelly, Alan Edward.