Canalization and plasticity in psychopathology

This theory-building paper (2022) introduces a new model of psychopathology called canalization, which is a form of plasticity that relates to increased model precision. It suggests that TEMP, combined with psychological support, can counter the entrenchment of canalization in pathological phenotypes, and offers suggestions for experiments to test its main hypotheses and implications.

Authors

  • Fernando Rosas
  • Richard Zeifman
  • Robin Carhart-Harris

Published

Neuropharmacology
meta Study

Abstract

This theoretical article revives a classical bridging construct, canalization, to describe a new model of a general factor of psychopathology. To achieve this, we have distinguished between two types of plasticity, an early one that we call ‘TEMP’ for ‘Temperature or Entropy Mediated Plasticity’, and another, we call ‘canalization’, which is close to Hebbian plasticity. These two forms of plasticity can be most easily distinguished by their relationship to ‘precision’ or inverse variance; TEMP relates to increased model variance or decreased precision, whereas the opposite is true for canalization. TEMP also subsumes increased learning rate, (Ising) temperature and entropy. Dictionary definitions of ‘plasticity’ describe it as the property of being easily shaped or molded; TEMP is the better match for this. Importantly, we propose that ‘pathological’ phenotypes develop via mechanisms of canalization or increased model precision, as a defensive response to adversity and associated distress or dysphoria. Our model states that canalization entrenches in psychopathology, narrowing the phenotypic statespace as the agent develops expertise in their pathology. We suggest that TEMP - combined with gently guiding psychological support - can counter canalization. We address questions of whether and when canalization is adaptive versus maladaptive, furnish our model with references to basic and human neuroscience, and offer concrete experiments and measures to test its main hypotheses and implications.

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Research Summary of 'Canalization and plasticity in psychopathology'

Introduction

Carhart-Harris and colleagues revive the biological concept of canalization to propose a parsimonious, transdiagnostic model of psychopathology. They contrast canalization — the development of stable, low-variance phenotypes — with forms of plasticity that increase phenotypic variability. Central to their framing is precision (inverse variance): canalization corresponds to increased precision and reduced sensitivity to new evidence, whereas a distinct form of plasticity they introduce, TEMP (Temperature or Entropy Mediated Plasticity), corresponds to decreased precision, increased variance, and higher learning rates. This distinction is used to reinterpret how entrenched cognitive and behavioural styles can develop and persist after adversity, distress or dysphoria. The paper sets out to do three things. First, it develops a theoretical model (CANAL) that treats the general psychopathology or 'p' factor as arising from entrenched canalized phenotypes. Second, it links this model to existing computational frameworks (notably the free-energy principle) and a specific mechanistic account of psychedelic action (the REBUS model), arguing that transient increases in TEMP can enable a simulated-annealing-like reconfiguration of maladaptive attractors. Third, the authors map this framework onto existing basic and clinical neuroscience findings, propose candidate biomarkers and experimental paradigms to test the model, and discuss clinical implications — including how psychedelic therapy plus supportive psychotherapy might counteract canalization.

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References (57)

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Canalization and plasticity in psychopathology — Research Summary & Context | Blossom