Function dictates the phase dependence of vision during human locomotion.
In human and animal locomotion, sensory input is thought to be processed in a phase-dependent manner. Here we use full-field transient visual scene motion toward or away from subjects walking on a treadmill. Perturbations were presented at three phases of walking to test 1) whether phase dependence is observed for visual input and 2) whether the nature of phase dependence differs across body segments. Results demonstrated that trunk responses to approaching perturbations were only weakly phase dependent and instead depended primarily on the delay from the perturbation. Recording of kinematic and muscle responses from both right and left lower limb allowed the analysis of six distinct phases of perturbation effects. In contrast to the trunk, leg responses were strongly phase dependent. Leg responses during the same gait cycle as the perturbation exhibited gating, occurring only when perturbations were applied in midstance. In contrast, during the postperturbation gait cycle, leg responses occurred at similar response phases of the gait cycle over a range of perturbation phases. These distinct responses reflect modulation of trunk orientation for upright equilibrium and modulation of leg segments for both hazard accommodation/avoidance and positional maintenance on the treadmill. Overall, these results support the idea that the phase dependence of responses to visual scene motion is determined by different functional tasks during walking.
Department of Kinesiology, University of Maryland, College Park, Maryland; Neuroscience and Cognitive Science Program, University of Maryland, College Park, Maryland;
David
D
Logan
Laboratory of Neuromotor Physiology, Santa Lucia Foundation, Rome, Italy;
Yuri P
YP
Ivanenko
Department of Kinesiology, University of Maryland, College Park, Maryland;
Tim
T
Kiemel
Laboratory of Neuromotor Physiology, Santa Lucia Foundation, Rome, Italy;
Germana
G
Cappellini
Laboratory of Neuromotor Physiology, Santa Lucia Foundation, Rome, Italy; Center of Space BioMedicine, University of Rome Tor Vergata, Rome, Italy; and.
Francesca
F
Sylos-Labini
Laboratory of Neuromotor Physiology, Santa Lucia Foundation, Rome, Italy; Center of Space BioMedicine, University of Rome Tor Vergata, Rome, Italy; and Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy.
Francesco
F
Lacquaniti
Department of Kinesiology, University of Maryland, College Park, Maryland; Neuroscience and Cognitive Science Program, University of Maryland, College Park, Maryland; Biomedical Engineering Graduate Program, University of Maryland, College Park, Maryland; Laboratory of Neuromotor Physiology, Santa Lucia Foundation, Rome, Italy; jjeka@temple.edu.
John J
JJ
Jeka
D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait; D006801:Humans; D007866:Leg / Q000294:innervation / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D011597:Psychomotor Performance; D014785:Vision, Ocular; D016138:Walking
human locomotion; phase dependence; vision