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Intermuscular Coordination of Mammalian Movement |
Principal Investigator: Felix E. Zajac, PhD
Project Staff: Steven A. Kautz, PhD, David A. Brown, PhD PT, and H.F. Machiel Van der Loos, PhD
Collaborators: Christine Raasch, PhD, Lena Ting, PhD, V. Rodney Hentz, MD, and Francisco Valero, PhD
Summary: Neurologically impaired persons, such as those with post-stroke hemiplegia, need to regain mobility. Restoration of mobility depends on being able to coordinate the muscles in the legs. The objective of this project is to elucidate the basic features of muscle coordination essential to human locomotion and cast this knowledge into a computer model of control of lower limb function.
Description: In order to understand how the central nervous system excites muscles to produce pedaling we are simulating the activity by computer. In an animated graphic display, each muscle becomes brighter as it is excited during the pedaling cycle. The simulation replicates the performance and muscle electrical activity recorded in laboratory studies of able-bodied subjects.
Problem: Developing rehabilitation strategies to restore ambulation to a neurologically impaired person is difficult, because the nervous system must coordinate many muscles to execute normal gait.
Approach: Computer models of muscle coordination for lower limb tasks, like walking and pedaling, let us discover the basic features of muscle coordination essential tomotor task execution. By studying computer simulations of pathological gait or pedaling, we can determine, first, how the basic features of muscle coordination are dysfunctional and, second, what level of improvement in gait or pedaling can be expected when only some of the basic features of coordination are restored through rehabilitation.
Findings: Control primitives have been identified by analyzing the biomechanics of pedaling. Three agonist-antagonist primitive pairs control coordination of each leg, where the two primitives of each pair alternate with each other in the crank cycle and, in bicycle pedaling, with their counterparts in the other leg. Experiments, where subjects pedal the novel apparatus, have shown that the generation of the pedaling pattern is inherently bilateral. Thus, the generation of the motor output in one leg, even in a unilateral task, is influenced by the sensorimotor state of the other leg.
Related Work: Similar work is directed toward designing better surgical reconstruction of hands of quadriplegics to improve their ability to grasp and manipulate objects.
Funding Source: NIH
Years: 1995-1999