title: Stride cycle influences on goal-directed head movements made during walking.
abstract: Horizontal head movements were studied in six subjects as they made rapid horizontal gaze adjustments while walking. The aim of the present research was to determine if gait cycle events alter the head movement response to a visual target acquisition task. Gaze shifts of approximately 40 degrees were elicited by a step change in the position of a visual target from a central location to a second location in the left or right horizontal periphery. The timing of the target position change was constrained to occur at 25%, 50%, 75% and 100% of the stride cycle. The trials were randomly presented as the subjects walked on a treadmill at their preferred speed (range: 1.25-1.48 m/s, mean: 1.39+/-0.09 m/s). Analyses focused on the movement onset latencies of the head and eyes and on the peak velocity and saccade amplitude of the head movement response. The head and eye movement onset latencies were not affected by either the direction of the target change or the point in the gait cycle during which the target relocation occurred. However, the presence of an interaction between the gait cycle events and the direction of the visual target shift for both the amplitude and peak velocity of the head movement response indicates that the head movement responses to visual target changes can be influenced by the phase of the gait cycle during which the target relocation takes place.
authors.affiliation: Neuroscience Laboratories, Wyle Life Sciences, 1290 Hercules Dr. Suite 120, Houston, TX 77058, USA. bpeters@ems.jsc.nasa.gov
authors.forename: Brian T
authors.initials: BT
authors.lastname: Peters
authors.forename: Richard E A
authors.initials: RE
authors.lastname: van Emmerik
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Bloomberg
mesh_terms: D000328:Adult; D005133:Eye Movements / Q000502:physiology*; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D008297:Male; D016138:Walking / Q000502:physiology*