AJP - Regulatory, Integrative and Comparative Physiology, Vol 239, Issue 1 93-114, Copyright © 1980 by American Physiological Society
Optimal and adaptive control in canine postural regulation
D. Schuster and R. E. Talbott
For analytic purposes, dogs trained to stand quietly on an oscillating
platform can be likened to a fixed-length inverted pendulum with a point
mass. Describing function analysis permitted derivation of torque and error
values as functions of phase and gain relative to platform movement. A
phase criterion was determined for minimization of either control torque at
a given error amplitude or error at a given control torque amplitude.
Describing functions for dogs with and without vision approached optimal
phase. Stretch reflex control involving proportional-plus-rate feedback is
not sufficient to account for the approach to optimal phase. Blindfolded
labyrinthectomized dogs did not exhibit optimal behavior and the phase
constraint for stretch reflex control was satisfied at most frequencies.
The observed behavior is best accounted for by a model involving both
otolith and visual feedforward (pursuit-precognitive) control processes.
Reductions in phase lag by blindfolded dogs during the first few cycles of
platform motion provide evidence of adaptive control.
