Changes in muscle coordination patterns induced by exposure to a viscous force field.
Robotic neurorehabilitation aims at promoting the recovery of lost function after neurological injury by leveraging strategies of motor learning. One important aspect of the rehabilitation process is the improvement of muscle coordination patterns, which can be drastically altered after stroke. However, it is not fully understood if and how robotic therapy can address these deficits. The aim of our study was to find how muscle coordination, analyzed from the perspective of motor modules, could change during motor adaptation to a dynamic environment generated by a haptic interface.



In our experiment we employed the traditional paradigm of exposure to a viscous force field to subjects that grasped the handle of an actuated joystick during a reaching movement (participants moved directly forward and back by 30 c m). EMG signals of ten muscles of the tested arm were recorded. We extracted motor modules from the pooled EMG data of all subjects and analyzed the muscle coordination patterns.



We found that the participants reacted by using a coordination strategy that could be explained by a change in the activation of motor modules used during free motion and by two complementary modules. These complementary modules aggregated changes in muscle coordination, and evolved throughout the experiment eventually maintaining a comparable structure until the late phase of re-adaptation.



This result suggests that motor adaptation induced by the interaction with a robotic device can lead to changes in the muscle coordination patterns of the subject.
Dept. of Management and Engineering, University of Padua, Via Venezia 1, Padua, 35135, Italy. fabio.oscari@unipd.it.
Fabio
F
Oscari
Dept. of Health Sciences and Research, Medical University of South Carolina, 77 President Street, MSC 700, Charleston, SC 29425, USA.
Christian
C
Finetto
Dept. of Health Sciences and Research, Medical University of South Carolina, 77 President Street, MSC 700, Charleston, SC 29425, USA.|Ralph H. Johnson VA Medical Center, Charleston, SC 29425, USA.
Steve A
SA
Kautz
Dept. of Management and Engineering, University of Padua, Via Venezia 1, Padua, 35135, Italy.
Giulio
G
Rosati
D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012371:Robotics / Q000379:methods*
Dynamic perturbation; Haptics; Learning; Motor adaptation; Motor modules; Robotics; Viscous field