caa a22 4500 463245555 CHVBK 20180405153324.0 cr unu---uuuuu 170326e20070201xx s 000 0 eng 10.1007/s00422-006-0112-6 doi (NATIONALLICENCE)springer-10.1007/s00422-006-0112-6 Resonance tuning in a neuro-musculo-skeletal model of the forearm [Elektronische Daten] [B. Verdaasdonk, H. Koopman, F. Van der Helm] In rhythmic movements, humans activate their muscles in a robust and energy efficient way. These activation patterns are oscillatory and seem to originate from neural networks in the spinal cord, called central pattern generators (CPGs). Evidence for the existence of CPGs was found for instance in lampreys, cats and rats. There are indications that CPGs exist in humans as well, but this is not proven yet. Energy efficiency is achieved by resonance tuning: the central nervous system is able to tune into the resonance frequency of the limb, which is determined by the local reflex gains. The goal of this study is to investigate if the existence of a CPG in the human spine can explain the resonance tuning behavior, observed in human rhythmic limb movement. A neuro-musculo-skeletal model of the forearm is proposed, in which a CPG is organized in parallel to the local reflexloop. The afferent and efferent connections to the CPG are based on clues about the organization of the CPG, found in literature. The model is kept as simple as possible (i.e., lumped muscle models, groups of neurons are lumped into half-centers, simple reflex model), but incorporates enough of the essential dynamics to explain behavior—such as resonance tuning—in a qualitative way. Resonance tuning is achieved above, at and below the endogenous frequency of the CPG in a highly non-linear neuro- musculo-skeletal model. Afferent feedback of muscle lengthening to the CPG is necessary to accomplish resonance tuning above the endogenous frequency of the CPG, while feedback of muscle velocity is necessary to compensate for the phase lag, caused by the time delay in the loop coupling the limb to the CPG. This afferent feedback of muscle lengthening and velocity represents the Ia and II fibers, which—according to literature—is the input to the CPG. An internal process of the CPG, which integrates the delayed muscle lengthening and feeds it to the half-center model, provides resonance tuning below the endogenous frequency. Increased co-contraction makes higher movement frequencies possible. This agrees with studies of rhythmic forearm movements, which have shown that co-contraction increases with movement frequency. Robustness against force perturbations originates mainly from the CPG and the local reflex loop. The CPG delivers an increasing part of the necessary muscle activation for increasing perturbation size. As far as we know, the proposed neuro-musculo-skeletal model is the first that explains the observed resonance tuning in human rhythmic limb movement. Springer-Verlag, 2006 Verdaasdonk B. Faculty of Engineering Technology, Department of Bio-mechanical Engineering, University of Twente, P.O.Box 217, 7500 AE, Enschede, The Netherlands aut Koopman H. Faculty of Engineering Technology, Department of Bio-mechanical Engineering, University of Twente, P.O.Box 217, 7500 AE, Enschede, The Netherlands aut Van der Helm F. Faculty of Engineering Technology, Department of Bio-mechanical Engineering, University of Twente, P.O.Box 217, 7500 AE, Enschede, The Netherlands aut Biological Cybernetics Springer-Verlag 96/2(2007-02-01), 165-180 0340-1200 96:2<165 2007 96 422 https://doi.org/10.1007/s00422-006-0112-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00422-006-0112-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Verdaasdonk B. Faculty of Engineering Technology, Department of Bio-mechanical Engineering, University of Twente, P.O.Box 217, 7500 AE, Enschede, The Netherlands aut NATIONALLICENCE 700 1- Koopman H. Faculty of Engineering Technology, Department of Bio-mechanical Engineering, University of Twente, P.O.Box 217, 7500 AE, Enschede, The Netherlands aut NATIONALLICENCE 700 1- Van der Helm F. Faculty of Engineering Technology, Department of Bio-mechanical Engineering, University of Twente, P.O.Box 217, 7500 AE, Enschede, The Netherlands aut NATIONALLICENCE 773 0- Biological Cybernetics Springer-Verlag 96/2(2007-02-01), 165-180 0340-1200 96:2<165 2007 96 422 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer