Allostasis, Interoception, and the Free Energy Principle

Fri, 12 Mar 2021 00:00:00 +0000

Introduction

The intersection of biological regulation, predictive processing, and consciousness represents one of the most fascinating frontiers in cognitive science today. After carefully reading Corcoran and Hohwy’s chapter “Allostasis, interoception, and the free energy principle: Feeling our way forward,” I’m struck by both its ambitious scope and its meticulous attention to conceptual clarity. This paper attempts to untangle a complex theoretical landscape that has profound implications for how we understand the relationship between mind, body, and environment.

The Conceptual Maze: Homeostasis and Allostasis

At its foundation, this paper addresses a fundamental question: how do biological organisms maintain their viability? The traditional answer has been homeostasis - the concept developed by Claude Bernard and Walter Cannon emphasizing the maintenance of stable internal conditions despite external fluctuations. The authors provide an excellent historical overview of this concept, tracing its development from Bernard’s emphasis on the “milieu intérieur” to Cannon’s more nuanced view of stability involving acceptable ranges rather than fixed setpoints.

What makes this paper particularly valuable is its careful examination of allostasis - a concept introduced by Sterling and Eyer in 1988 as “stability through change”. The authors meticulously document how this concept has evolved in multiple, sometimes contradictory directions:

Sterling and Eyer’s radical position that allostasis should entirely replace homeostasis
McEwen’s view of allostasis as “the process for actively maintaining homeostasis”
Schulkin’s perspective where homeostasis and allostasis are complementary mechanisms for maintaining biological viability

This historical excavation reveals something important: allostasis has been a contested concept from the beginning, with no clear consensus about its precise meaning even 30+ years after its introduction.

Free Energy and Interoceptive Inference

The paper becomes even more interesting when it examines how these biological regulation concepts have been incorporated into the free energy principle framework. The authors identify three distinct interpretations of allostasis within recent free energy-inspired accounts:

Behavioral allostasis: Focuses on behavioral actions on the external world to maintain internal states (Gu & FitzGerald, Seth)
Teleological allostasis: Positions allostasis as the primary evolutionary design feature of the brain (Barrett and colleagues)
Diachronic allostasis: Emphasizes allostasis as operating across various timescales (Pezzulo et al., Stephan et al.)

The authors' critique of the “behavioral” interpretation is particularly insightful. They point out that despite using the term “allostasis,” these accounts describe what is essentially a reactive process - responding to homeostatic perturbations rather than anticipating them. This seems to miss the core predictive emphasis that has been central to allostasis from its inception.

Strengths of the Analysis

What I find most impressive about Corcoran and Hohwy’s analysis is its conceptual precision. In a literature full of terminological confusion and competing definitions, they bring much-needed clarity. Their systematic examination of different interpretations helps untangle what has become a rather messy theoretical landscape.

The authors are also admirably even-handed in their assessment. While they ultimately favor a view that reconciles homeostasis and allostasis as complementary strategies, they carefully consider the merits of alternative perspectives. Their analysis of the “diachronic” interpretation of allostasis (particularly Stephan’s Bayesian implementation of hierarchical allostatic control) is especially thoughtful.

I also liked their recognition that “sustained biological viability (rather than some other criterion such as internal stability) seems to us the most plausible target towards which physiological and behavioral regulatory mechanisms are striving”. This shifts the focus from mechanism to purpose in a way that offers a principled resolution to some of the conceptual tensions.

Questions for Further Investigation

Reading this paper has sparked several questions that I believe could be subjects for further investigation:

Developmental Trajectory: How do homeostatic and allostatic regulatory mechanisms develop over the lifespan? Are there critical periods for the development of predictive regulatory capacities?
Individual Differences: What accounts for the substantial variability in regulatory strategies across individuals? Some people seem to rely more on anticipatory regulation, while others show more reactive patterns.
Artificial Systems: Could the complementary frameworks of homeostasis and allostasis inform the design of artificial systems? Might robotic or AI systems benefit from implementing both reactive and anticipatory modes of self-regulation?
Disorders of Regulation: How do disruptions in the relationship between homeostasis and allostasis contribute to physical and mental health conditions? The concept of “allostatic load” is mentioned but deserves deeper exploration.
Consciousness and Regulation: If predictive regulation is indeed fundamental to biological systems, what implications does this have for theories of consciousness? Could consciousness itself be understood partly as an extension of these regulatory processes?