It is assumed that the coordinated control of the muscles of an individual joint is based on the propagation of excitation wave over a central linearly ordered neuronal ensemble. With shift in the wave front the number of tonically active output neurones of the ensemble increases making discrete contributions to change in the output motor command determined in terms of shift in the force-length muscular characteristics. By changing the wave speed the nervous system may influence the speed of movement of a limb. To verify the wave model the authors have analysed the time trajectories of ballistic movements differing in the final values of the joint angle. The experimental findings demonstrate the possibility of formation of groups of trajectories with the following properties: 1) the initial portions of the trajectories of movements concur; 2) the duration of concordance like the time of the movement itself increases with rise in amplitude; 3) by summing two natural trajectories one of which is shifted relative to the other in time one may synthesize the natural ballistic trajectories of the corresponding amplitude; and 4) property 3) may be generalized to the case of many items. The results confirm the main implications of the hypothesis on the wave organization of the central control of movements in the individual joint.
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|Published - Dec 1 1984
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