From homeostasis to allodynamic regulation

INTRODUCTION Since the seminal work of Walter Cannon, the concept of homeostasis, which he described as “the coordinated physiological processes which maintain most of the steady states in the organism” (Cannon, 1929b, p. 400), has been a major force in the development of views of physiological regulation and control. The homeostatic construct also importantly shaped many twentieth-century psychological concepts and theories, including models of reinforcement, motivation, perception, personality, and psychosomatic disorders. This construct has been particularly salient in psychophysiology and behavioral medicine, because of the putative role of autonomic and neuroendocrine systems in the regulation of homeostatic processes, and vice versa (Berntson & Cacioppo, 2007; Critchley & Harrison, 2013; Norman, Berntson, & Cacioppo, 2014). The present chapter will explore the current status of the homeostatic model, and the emergence of modern concepts of allostasis and allodynamic regulation. A second aim of the chapter is to consider the organization of systems and mechanisms that underlie functional physiological regulation and psychophysiological relationships. A complication in drawing clear psychophysiological relations is the fact that associations between psychological and physiological constructs cut across systems and processes represented at distinct levels of conceptualization and analysis. One goal of multilevel integrative analyses is to permit a more accurate appreciation of the underlying links and organizations (Cacioppo, Berntson, Sheridan, & McClintock, 2000). Integrative analysis across psychological and physiological levels is still very much a work in progress and psychophysiology resides at a critical intersection to pursue this integration. In considering the psychophysiology of the autonomic nervous system as an exemplar, the present chapter will identify some aspects of a broad framework that may contribute to the emergence of an integrative psychophysiology. Homeostasis and Homeodynamic Regulation Origins of the Homeostatic Concept The notion of natural balancing or equilibrium-seeking tendencies may be traced back as early as Hippocrates (Cofer & Appley, 1964). The term homeostasis, and the contemporary negative feedback model of homeostatic regulation has a more recent history. Claude Bernard (1878/1974) reflected on the relative constancy of the internal environment (milieu intérieur) of living creatures. This constancy was seen to reflect an organism’s ability to stabilize the cellular environment, despite powerful entropic forces that threaten to disrupt the biological order essential for life.