Journal of Neurophysiology, Vol 74, Issue 4 1374-1381, Copyright © 1995 by APS

ARTICLES

Organizing principles for voluntary movement: extending single-joint rules

G. L. Almeida, D. A. Hong, D. Corcos and G. L. Gottlieb
School of Kinesiology (M7C 194), University of Illinois at Chicago 60680, USA.

1. Four subjects performed fast flexions of the elbow or shoulder over three different distances. Elbow flexions were performed both in a horizontal, single-degree-of-freedom manipulandum and in a sagittal plane with the limb unconstrained. Shoulder flexions were only performed in the sagittal plane by the unconstrained limb. We simultaneously recorded kinematic and electromyographic (EMG) patterns at the "focal" joint, that which the subject intentionally flexed, and at the other, "nonfocal" joint that the subject had been instructed to not flex. 2. Comparisons of the elbow EMG patterns across tasks show that agonist and antagonist muscles were similar in pattern but not size, reflecting the net muscle torque patterns. Comparisons at the shoulder also revealed similar EMG patterns across tasks that reflected net muscle torques. 3. Comparisons of EMG patterns across joints show that elbow and shoulder flexors behaved similarly. This was not true of the extensors. The triceps EMG burst was delayed for longer distances but the posterior deltoid had an early, distance-invariant onset. 4. Similarities in EMG reflect torque demands required at the focal joint to produce flexion and at the nonfocal joint to reduce extension induced by dynamic interactions with the focal, flexing joint. These similarities appear despite very different kinematic intentions and outcomes. This argues against a strong role for length-sensitive reflexes in their generation. 5. These results support the hypothesis that movements are controlled by muscle activation patterns that are planned for the expected torque requirements of the task. This general rule is true whether we are performing single-joint or multiple-joint movements, with or without external constraints. The similarities between single-joint and multijoint movement control may be a consequence of ontogenetic development of multijoint movement strategies that prove useful and are therefore also expressed under the constrained conditions of specialized tasks such as those performed in single-joint manipulanda.

This article has been cited by other articles:

				D. B. Debicki and P. L. Gribble Inter-Joint Coupling Strategy During Adaptation to Novel Viscous Loads in Human Arm Movement J Neurophysiol, August 1, 2004; 92(2): 754 - 765. [Abstract] [Full Text] [PDF]

				K. M. Zackowski, A. W. Dromerick, S. A. Sahrmann, W. T. Thach, and A. J. Bastian How do strength, sensation, spasticity and joint individuation relate to the reaching deficits of people with chronic hemiparesis? Brain, May 1, 2004; 127(5): 1035 - 1046. [Abstract] [Full Text] [PDF]

				M. Hirashima, K. Kudo, and T. Ohtsuki Utilization and Compensation of Interaction Torques During Ball-Throwing Movements J Neurophysiol, April 1, 2003; 89(4): 1784 - 1796. [Abstract] [Full Text] [PDF]

				P. Pigeon, S. B. Bortolami, P. DiZio, and J. R. Lackner Coordinated Turn-and-Reach Movements. I. Anticipatory Compensation for Self-Generated Coriolis and Interaction Torques J Neurophysiol, January 1, 2003; 89(1): 276 - 289. [Abstract] [Full Text] [PDF]

				D. M. Shiller, D. J. Ostry, P. L. Gribble, and R. Laboissiere Compensation for the Effects of Head Acceleration on Jaw Movement in Speech J. Neurosci., August 15, 2001; 21(16): 6447 - 6456. [Abstract] [Full Text] [PDF]

				G. F. Koshland, J. C. Galloway, and C. J. Nevoret-Bell Control of the Wrist in Three-Joint Arm Movements to Multiple Directions in the Horizontal Plane J Neurophysiol, May 1, 2000; 83(5): 3188 - 3195. [Abstract] [Full Text] [PDF]

				P. L. Gribble and D. J. Ostry Compensation for Interaction Torques During Single- and Multijoint Limb Movement J Neurophysiol, November 1, 1999; 82(5): 2310 - 2326. [Abstract] [Full Text] [PDF]

				G. L. Gottlieb, Q. Song, G. L. Almeida, D.-A. Hong, and D. Corcos Directional Control of Planar Human Arm Movement J Neurophysiol, December 1, 1997; 78(6): 2985 - 2998. [Abstract] [Full Text] [PDF]