Abstract
It has been shown that during arm movement, humans selectively change the endpoint stiffness of their arm to compensate for the instability in an unstable environment. When the direction of the instability is rotated with respect to the direction of movement, it was found that humans modify the antisymmetric component of their endpoint stiffness. The antisymmetric component of stiffness arises due to reflex responses suggesting that the subjects may have tuned their reflex responses as part of the feedforward adaptive control. The goal of this study was to examine whether the CNS modulates the gain of the reflex response for selective tuning of endpoint impedance. Subjects performed reaching movements in three unstable force fields produced by a robotic manipulandum, each field differing only in the rotational component. After subjects had learned to compensate for the field, allowing them to make unperturbed movements to the target, the endpoint stiffness of the arm was estimated in the middle of the movements. At the same time electromyographic activity (EMG) of six arm muscles was recorded. Analysis of the EMG revealed differences across force fields in the reflex gain of these muscles consistent with stiffness changes. This study suggests that the CNS modulates the reflex gain as part of the adaptive feedforward command in which the endpoint impedance is selectively tuned to overcome environmental instability.
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References
Rancourt, D., Hogan, N.: Stability in force-production tasks. J. Mot. Behav. 33, 193–204 (2001)
Harris, C.M., Wolpert, D.M.: Signal-dependent noise determines motor planning. Nature 394, 780–784 (1998)
Burdet, E., Osu, R., Franklin, D.W., Milner, T.E., Kawato, M.: The central nervous system stabilizes unstable dynamics by learning optimal impedance. Nature 414, 446–449 (2001)
Takahashi, C.D., Scheidt, R.A., Reinkensmeyer, D.J.: Impedance control and internal model formation when reaching in a randomly varying dynamical environment. J. Neurophysiol. 86, 1047–1051 (2001)
Hogan, N.: The mechanics of multi-joint posture and movement control. Biol. Cybern. 52, 315–331 (1985)
Franklin, D.W., So, U., Kawato, M., Milner, T.E.: Impedance control balances stability with metabolically costly muscle activation. J. Neurophysiol. 92, 3097–3105 (2004)
Franklin, D.W., Liaw, G., Milner, T.E., Osu, R., Burdet, E., Kawato, M.: End-point stiffness of the arm is directionally tuned to instability in the environment. J. Neurosci. (2007)
Mussa-Ivaldi, F.A., Hogan, N., Bizzi, E.: Neural, mechanical, and geometric factors subserving arm posture in humans. J. Neurosci. 5, 2732–2743 (1985)
Gomi, H., Kawato, M.: Human arm stiffness and equilibrium-point trajectory during multi-joint movement. Biol. Cybern. 76, 163–171 (1997)
Burdet, E., Osu, R., Franklin, D.W., Yoshioka, T., Milner, T.E., Kawato, M.: A method for measuring endpoint stiffness during multi-joint arm movements. J. Biomech. 33, 1705–1709 (2000)
Gomi, H., Osu, R.: Task-dependent viscoeleasticity of human multijoint arm and its spatial characteristics for interaction with environments. J. Neurosci. 18, 8965–8978 (1998)
Ito, T., Murano, E.Z., Gomi, H.: Fast force-generation dynamics of human articulatory muscles. J. Appl. Physiol. 96, 2318–2324 (2004)
Grey, M.J., Pierce, C.W.P., Milner, T.E., Sinkjær, T.: Soleus stretch reflex during cycling. Motor Control 1, 36–49 (2001)
Lacquaniti, F., Maioli, C.: Anticipatory and reflex coactivation of antagonist muscles in catching. Brain Res. 406, 373–378 (1987)
Gomi, H., Saijyo, N., Haggard, P.: Coordination of multi-joint arm reflexes is modulated during interaction with environments. In: 12th Annual Meeting of Neural Control of Movement, E-09, Naples, Florida (2002)
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Liaw, G., Franklin, D.W., Burdet, E., Kadi-allah, A., Kawato, M. (2008). Reflex Contributions to the Directional Tuning of Arm Stiffness. In: Ishikawa, M., Doya, K., Miyamoto, H., Yamakawa, T. (eds) Neural Information Processing. ICONIP 2007. Lecture Notes in Computer Science, vol 4984. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-69158-7_94
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DOI: https://doi.org/10.1007/978-3-540-69158-7_94
Publisher Name: Springer, Berlin, Heidelberg
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