Exploration of joint redundancy but not task space variability facilitates supervised motor learning

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 113; no. 50; pp. 14414 - 14419
• Main Authors: Singh, Puneet, Jana, Sumitash, Ghosal, Ashitava, Murthy, Aditya
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 13.12.2016
• Subjects: Adult; Aged; Arm; Biological Sciences; Biomechanical Phenomena; Enteral Nutrition; Female; Functional Laterality - physiology; Humans; Joints - physiology; Kinematics; Learning - physiology; Male; Middle Aged; Models, Biological; Motor ability; Motor Skills - physiology; Muscles; Muscular system; Noise control; Psychomotor Performance - physiology; Task Performance and Analysis; Young Adult; reaching; motor control; supervised learning; minimum-intervention principle; motor noise
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1613383113

The number of joints and muscles in a human arm is more than what is required for reaching to a desired point in 3D space. Although previous studies have emphasized how such redundancy and the associated flexibility may play an important role in path planning, control of noise, and optimization of motion, whether and how redundancy might promote motor learning has not been investigated. In this work, we quantify redundancy space and investigate its significance and effect on motor learning. We propose that a larger redundancy space leads to faster learning across subjects. We observed this pattern in subjects learning novel kinematics (visuomotor adaptation) and dynamics (force-field adaptation). Interestingly, we also observed differences in the redundancy space between the dominant hand and nondominant hand that explained differences in the learning of dynamics. Taken together, these results provide support for the hypothesis that redundancy aids in motor learning and that the redundant component of motor variability is not noise.