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Effect of external viscous load on head movementQuantitative measurements of horizontal head rotation were obtained from normal human subjects intending to make 'time optimal' trajectories between targets. By mounting large, lightweight vanes on the head, viscous damping B, up to 15 times normal could be added to the usual mechanical load of the head. With the added viscosity, the head trajectory was slowed and of larger duration (as expected) since fixed and maximal (for that amplitude) muscle forces had to accelerate the added viscous load. This decreased acceleration and velocity and longer duration movement still ensued in spite of adaptive compensation; this provided evidence that quasi-'time optimal' movements do indeed employ maximal muscle forces. The adaptation to this added load was rapid. Then the 'adapted state' subjects produced changed trajectories. The adaptation depended in part on the differing detailed instructions given to the subjects. This differential adaptation provided evidence for the existence of preprogrammed controller signals, sensitive to intended criterion, and neurologically ballistic or open loop rather than modified by feedback from proprioceptors or vision.
Document ID
Document Type
Reprint (Version printed in journal)
Nam, M.-H. (Kon-Kuk University Seoul, Republic of Korea, United States)
Lakshminarayanan, V. (California Univ. Berkeley, CA, United States)
Stark, L. W. (California, University Berkeley, CA, United States)
Date Acquired
August 12, 2013
Publication Date
March 1, 1984
Publication Information
Publication: IEEE Transactions on Biomedical Engineering
Volume: BME-31
ISSN: 0018-9294
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Funding Number(s)
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