Control of wrist movement in deafferented man: evidence for a mixed strategy of position and amplitude control.

Miall, R.C., Haggard, P. and Cole, J., 2017. Control of wrist movement in deafferented man: evidence for a mixed strategy of position and amplitude control. Experimental Brain Research, 1 - 14. (In Press)

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DOI: 10.1007/s00221-017-5066-5

Abstract

© 2017 The Author(s) There is a continuing debate about control of voluntary movement, with conflicted evidence about the balance between control of movement vectors (amplitude control) that implies knowledge of the starting position for accuracy, and equilibrium point or final position control, that is independent of the starting conditions. We tested wrist flexion and extension movements in a man with a chronic peripheral neuronopathy that deprived him of proprioceptive knowledge of his wrist angles. In a series of experiments, we demonstrate that he could scale the amplitude of his wrist movements in flexion/extension, even without visual feedback, and appeared to adopt a strategy of moving via a central wrist position when asked to reach target angles from unknown start locations. When examining the relationship between positional error at the start and end of each movement in long sequences of movements, we report that he appears to have three canonical positions that he can reach relatively successfully, in flexion, in extension and in the centre. These are consistent with end-point or position control. Other positions were reached with errors that suggest amplitude control. Recording wrist flexor and extensor EMG confirmed that the flexion and extension canonical positions were reached by strong flexor and extensor activity, without antagonist activity, and other positions were reached with graded muscle activation levels. The central canonical position does not appear to be reached by either maximal co-contraction or by complete relaxation, but may have been reached by matched low-level co-contraction.

Item Type:Article
ISSN:0014-4819
Group:Faculty of Health & Social Sciences
ID Code:29649
Deposited By: Unnamed user with email symplectic@symplectic
Deposited On:04 Sep 2017 13:10
Last Modified:04 Sep 2017 13:10

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