Understanding negative feedback and classical conditioning of autonomic responses in physiological regulation.

Physiological regulation is achieved via a complex and highly integrated network of innate autonomic and somatic reflexes combined with learned responses acquired through experience. Historically, scholars investigating homeostatic regulation focused on the intricate innate reflexes, with little or no consideration of the key role of experience and learning. Our goal in this perspective paper is to provide increased clarity as well as a more nuanced understanding of the roles of negative feedback and feedforward mechanisms in thermoregulation with relevance to the broader field of physiological regulation. While physiological regulation requires innate regulatory reflexes and negative feedback control, we contend that learning also plays a key role when animals are confronted with common or recurring regulatory challenges. Animals readily acquire knowledge as to when regulatory disturbances are likely to occur and, accordingly, can learn to make anticipatory responses that minimize or eliminate completely the expected disturbance. We focus on how regulatory responses learned via classical conditioning enable more rapid and more efficient regulation than would result from negative feedback alone. Learning builds upon the foundation provided by innate regulatory reflexes and negative feedback and thereby improves the strength and timing of regulatory responses. We argue that a more inclusive approach to understanding physiological regulation, one recognizing the important roles played by both innate and learned reflexes to achieve regulation, will yield more innovative and productive research.