Format

Send to

Choose Destination
J Neurophysiol. 2013 Oct;110(7):1611-20. doi: 10.1152/jn.00294.2013. Epub 2013 Jul 10.

Cerebellar ataxia impairs modulation of arm stiffness during postural maintenance.

Author information

1
Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland;

Abstract

Impedance control enables humans to effectively interact with their environment during postural and movement tasks, adjusting the mechanical behavior of their limbs to account for instability. Previous work has shown that people are able to selectively modulate the end-point stiffness of their arms, adjusting for varying directions of environmental disturbances. Behavioral studies also suggest that separate controllers are used for impedance modulation versus joint torque coordination. Here we tested whether people with cerebellar damage have deficits in impedance control. It is known that these individuals have poor motor coordination, which has typically been attributed to deficits in joint torque control. Subjects performed a static postural maintenance task with two different types of directional force perturbations. On average, patients with cerebellar ataxia modified stiffness differentially for the two perturbation conditions, although significantly less than age-matched control subjects. Thus cerebellar damage may impair the ability to modulate arm impedance. Surprisingly, the patients' intact ability to generally alter their limb stiffness during the postural task (albeit less than age-matched control subjects) improved their movement performance in a subsequent tracing task. The transfer of stiffness control from the static to the movement task may be a strategy that can be used by patients to compensate for their motor deficits.

KEYWORDS:

arm stiffness; cerebellar ataxia; impedance control

PMID:
23843434
PMCID:
PMC4042412
DOI:
10.1152/jn.00294.2013
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Atypon Icon for PubMed Central
Loading ...
Support Center