Learning dynamic control of body roll orientation

• Published in: Experimental brain research Vol. 234; no. 2; pp. 483 - 492
• Main Authors: Vimal, Vivekanand Pandey, Lackner, James R., DiZio, Paul
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2016; Springer; Springer Nature B.V
• Subjects: Adolescent; Adult; Biomedical and Life Sciences; Biomedicine; Equilibrium; Female; Humans; Learning - physiology; Male; Motion perception (Vision); Motor learning; Neurology; Neurosciences; Orientation - physiology; Physiological aspects; Pilot Projects; Postural Balance - physiology; Psychological aspects; Research Article; Rotation; Young Adult; United States; United States > US; Phase portraits; Stabilogram diffusion function; Dynamic balancing; Gravitational vertical; Vestibular system; Orientation; Vehicle control
• ISSN: 0014-4819; 1432-1106; 1432-1106
• DOI: 10.1007/s00221-015-4469-4

Our objective was to examine how the control of orientation is learned in a task involving dynamically balancing about an unstable equilibrium point, the gravitational vertical, in the absence of leg reflexes and muscle stiffness. Subjects ( n  = 10) used a joystick to set themselves to the gravitational vertical while seated in a multi-axis rotation system (MARS) device programmed with inverted pendulum dynamics. The MARS is driven by powerful servomotors and can faithfully follow joystick commands up to 2.5 Hz with a 30-ms latency. To make the task extremely difficult, the pendulum constant was set to 600°/s 2 . Each subject participated in five blocks of four trials, with a trial ending after a cumulative 100 s of balancing, excluding reset times when a subject lost control. To characterize performance and learning, we used metrics derived from joystick movements, phase portraits (joystick deflections vs MARS position and MARS velocity vs angular position), and stabilogram diffusion functions. We found that as subjects improved their balancing performance, they did so by making fewer destabilizing joystick movements and reducing the number and duration of joystick commands. The control strategy they acquired involved making more persistent short-term joystick movements, waiting longer before making changes to ongoing motion, and only intervening intermittently.