AJP - Regulatory, Integrative and Comparative Physiology, Vol 243, Issue 3 363-R372, Copyright © 1982 by American Physiological Society
Negative and positive feedback of central nervous system temperature in thermoregulation of pigeons
I. Schmidt and E. Simon
Experimental alterations of spinal cord and hypothalamic temperature
affecting behavioral and autonomic cold defense were investigated in
pigeons under external cold load with access to instrumental heat
reinforcement. Warming and cooling spinal cord resulted in
negative-feedback effects on both instrumental and autonomic cold defense.
Hypothalamic warming produced similar negative-feedback effects, whereas
hypothalamic cooling produced either no effect or positive-feedback effects
on both kinds of cold defense. As determined in previous studies,
hypothalamic temperature displacements under heat-load conditions produced
only negative-feedback effects on instrumental heat defense. However, only
positive-feedback effects were observed on autonomic heat defense by
panting. The diverse response patterns of autonomic and behavioral
thermoregulatory effectors to changing hypothalamic temperature under heat-
and cold-load conditions could be quantitatively described by a
mathematical model that takes into account 1) a greater Q10 for
intrahypothalamic transmission of the cold signal input than of the warm
signal input, and 2) different weights of extra- and intrahypothalamic
temperature signal inputs for the control of different effectors.
