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Volume 43 Number 5, August/September 2006
Pages 605 — 618

Abstract - Motions or muscles? Some behavioral factors underlying robotic assistance of motor recovery

Neville Hogan, PhD;1-2* Hermano I. Krebs, PhD;1,3 Brandon Rohrer, PhD;1 Jerome J. Palazzolo, PhD;1
Laura Dipietro, PhD;1 Susan E. Fasoli, ScD;1 Joel Stein, MD;4 Richard Hughes, PT, NCS;4 Walter R.
Frontera, MD, PhD;4 Daniel Lynch, OTR/L;5 Bruce T. Volpe, MD3,5

1Newman Laboratory, Department of Mechanical Engineering and 2Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; 3Department of Neurology and Neuroscience, Weill
Medical College of Cornell University, White Plains, NY; 4Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital and Harvard Medical School, Boston, MA; 5Burke Medical Research Institute, White Plains, NY
Abstract — Robotics and related technologies have begun to realize their promise to improve the delivery of rehabilitation therapy. However, the mechanism by which they enhance recovery remains unclear. Ultimately, recovery depends on biology, yet the details of the recovery process remain largely unknown; a deeper understanding is important to accelerate refinements of robotic therapy or suggest new approaches. Fortunately, robots provide an excellent instrument platform from which to study recovery at the behavioral level. This article reviews some initial insights about the process of upper-limb behavioral recovery that have emerged from our work. Evidence to date suggests that the form of therapy may be more important than its intensity: muscle strengthening offers no advantage over movement training. Passive movement is insufficient; active participation is required. Progressive training based on measures of movement coordination yields substantially improved outcomes. Together these results indicate that movement coordination rather than muscle activation may be the most appropriate focus for robotic therapy.
Key words: active-assistance therapy, adaptation, cerebrovascular accident, hemiparesis, motor learning, passive-resistance therapy, rehabilitation, robotic therapy, submovements, upper limb.

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