What do We Plan or Control When We Perform a Voluntary Movement?
The quantitative analysis of multiple degree of freedom movements is a relatively recent practice in motor control. In the early 1980s, Morasso, Lacquaniti, and Soechting published studies of arm reaching that identified certain distinctive kinematic characteristics (Morasso 1981; Soechting and Lacquaniti 1981; Lacquaniti et al. 1982). Morasso noted (p. 224) that “the common features among the different reaching movements are the single-peaked shape of the hand tangential velocity and the [straight] shape of the hand trajectory.” Soechting and Lacquaniti further noted that these properties were unaffected by changes in the load held in the hand or by the intended speed of movement. These properties of straightness and “bell-shaped” velocity profiles have become defining features of unconstrained human reaching movements, even though Hollerbach (1982) noted that movements in the sagittal plane tended to be more curved than those in the horizontal plane.
KeywordsEquilibrium Point Voluntary Movement Joint Torque Central Command Muscle Torque
Unable to display preview. Download preview PDF.
- Bastian, A.J., Martin, T.A., Keating, J.G., and Thach, W.T. (1996). Cerebellar ataxia: abnormal control of interaction torques across multiple joints. J. Neurophysiol. Google Scholar
- Gottlieb, G.L. (1996). On the voluntary movement of compliant (inertial-viscoelastic) loads by parcellated control mechanisms. J. Neurophysiol., 76(5); (in press).Google Scholar
- Gottlieb, G.L., Song, Q., Hong, D., Almeida, G.L., and Corcos, D.M. (1996a). Coordinating movement at two joints: a principal of linear covariance. J. Neurophysiol., 75(4):1160–1764.Google Scholar
- Hogan, N. (1984). An organizing principal for a class of voluntary movements. J. Neurosci., 11:2745–2754.Google Scholar
- Hollerbach, J.M. (1982). Computers, brains and the control of movement. TINS, 5:189–192.Google Scholar