Biological Self-organisation and Markov blankets

Abstract

Biological self-organisation is a process of spontaneous pattern formation; namely the emergence of coherent and stable systemic configurations that distinguish themselves from their environment. This process can occur at various spatial scales: from the microscopic (giving rise to cells) to the macroscopic (the emergence of organisms). Self-organisation at each level is essential to account for the hierarchical organisation of living organisms (organelles within cells, within tissues, within organs, etc.). In this paper, we pursue the idea that Markov blankets -statistical boundaries separating states that are external to a system from its internal states -emerge at every possible level of the description of the (living) system. Through simulations, we show that the concept of a Markov blanket is fundamental in defining biological systems and underwrites the nature and form of interactions between successive levels of hierarchical structure. We demonstrate the validity of our argument using simulations, based on the normative principle of variational free energy minimisation. Specifically, we adopt a top-down approach to provide a proof of concept for the claim that the self-organisation of Markov blankets (and blankets of blankets) underwrites the self-evidencing, autopoietic behaviour of living systems.

A Multi-scale View of the Emergent Complexity of Life: A Free-Energy Proposal

“…The notion of a Markov blanket, and the independencies between states it induces, can be directly applied to biological systems (Friston, 2013;Palacios et al, 2017). For example, the interior of a cell can be related to the internal states of the cell (e.g., cell metabolism), the extracellular environment to its external states, and the cell boundary to the Markov blanket that couples intracellular and extracellular states to one another.…”

“…Moving up the hierarchy of Markov blankets entails an increase in spatial and temporal scales. Any system that can be distinguished from its environment (and thus, possesses a Markov blanket) can take part in a dynamical interaction that produces a Markov blanket at a higher level of organization (Palacios et al, 2017).…”

The Predictive Brain: A Modular View of Brain and Cognitive Function?

“…In this sense, the Markov blanket is best understood as a boundary (Schrödinger 1943). Markov blanket boundaries can be found at many different scales of life, from macromolecules to organelles, organs and humans (Clark 2017;Hipólito 2019;Kirchhoff et al 2018;Kirchhoff & Kiverstein 2019;Palacios et al 2017;Ramstead et al 2017). A key aspect of a Markov blanket is that it yields a formal way by which to define what it means for internal and external states to be conditionally independent of one another given a third set of states: active and sensory states.…”

“…On the one hand, external states, E, cause sensory states, S, which influence, but are not also influenced by, internal states, I. On the other hand, internal states cause active states, A, which influence, but are not themselves influenced by, external states (Friston et al 2015;Kirchhoff et al 2018;Palacios et al 2017).…”

From Allostatic Agents to Counterfactual Cognisers: Active Inference, Biological Regulation, and The Origins of Cognition

“…Note that complex organisms may be composed of multiple, hierarchically-nested Markov blankets (for recent discussion, seeAllen and Friston 2018;Clark 2017;Kirchhoff et al 2018;Palacios et al 2017;Ramstead et al 2018).…”