Neural control on multiple time scales: Insights from human stick balancing

• Published in: Condensed Matter Physics
• Date: 2006
• Main Authors: Cabrera, J.L., Luciani, C., Milton, J.
• Format: Article
• Language: English
• Published: Інститут фізики конденсованих систем НАН України 2006
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/121324
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Neural control on multiple time scales: Insights from human stick balancing / J.L. Cabrera, C. Luciani, J. Milton // Condensed Matter Physics. — 2006. — Т. 9, № 2(46). — С. 373–383. — Бібліогр.: 42 назв. — англ.

The time-delayed feedback control mechanisms of the nervous system are continuously subjected to the
 effects of uncontrolled random perturbations (herein referred to as noise). In this setting the statistical properties
 of the fluctuations in the controlled variable(s) can provide non-invasive insights into the nature of the
 underlying control mechanisms. We illustrate this concept through a study of stick balancing at the fingertip
 using high speed motion capture techniques. Experimental observations together with numerical studies of a
 stochastic delay differential equation demonstrate that on time scales short compared to the neural time delay
 (“fast control”), parametric noise provides a non-predictive mechanism that transiently stabilizes the upright
 position of the balanced stick. Moreover, numerical simulations of a delayed random walker with a repulsive
 origin indicate that even an unstable fixed point can be transiently stabilized by the interplay between noise
 and time delay. In contrast, on time scales comparable to the neural time delay (“slow control”), feedback and
 feedforward control mechanisms become more important. The relative contribution of the fast and slow control
 mechanisms to stick balancing is dynamic and, for example, depends on the context in which stick balancing
 is performed and the expertise of the balancer.