Showing papers by "James J. Collins published in 1992"
TL;DR: In the present work, the quadrupedal locomotor central pattern generator is modelled as four distinct but symmetrically coupled nonlinear oscillators, showing that the typical patterns for two such networks of oscillators include 2:1 frequency-locked oscillations.
Abstract: The generation and control of animal locomotion is believed to involve central pattern generators — networks of neurons which are capable of producing oscillatory behavior. In the present work, the quadrupedal locomotor central pattern generator is modelled as four distinct but symmetrically coupled nonlinear oscillators. We show that the typical patterns for two such networks of oscillators include 2:1 frequency-locked oscillations. These patterns, which arise through symmetry-breaking Hopf bifurcation, correspond in part to observed patterns of 2:1 frequency-locking of limb movements during electrically elicited locomotion of decerebrate and spinal quadrupeds. We briefly describe how our theoretical predictions could be tested experimentally.
57 citations
Patent•
09 Dec 1992TL;DR: In this paper, the mean square displacement of the center of pressure beneath a subject's feet vs the time interval is calculated as a stabilogram diffusion plot, since reproducible, provides physiologically meaningful information from which an assessment of the subject's postural control system can be made.
Abstract: A method and an apparatus for analyzing the human postural control system includes computing the mean square displacement of the center of pressure beneath a subject's feet vs. the time interval. The result is plotted as a stabilogram diffusion plot. The stabilogram diffusion plot, since reproducible, provides physiologically meaningful information from which an assessment of the subject's postural control system can be made. A Brownian diffusion coefficient, which is indicative of the level of stochastic activity of the center of pressure, can be calculated from the slope of the stabilogram diffusion plot. Also, from the slope of the log-log stabilogram diffusion plot, a determination can be made as to whether the system is moving closer to or away from a state of relative equilibrium. Finally, a short term open-loop postural control scheme, which operates before a long term closed-loop feedback postural control scheme activates, can be studied from the stabilogram diffusion plot. Also, from the stabilogram diffusion plot, a determination can be made as to when the postural control system switches from open-loop control to closed-loop control.
48 citations
1 citations