On the meaning of ‘plasticity’ in neuroscience and mental health research and its relation to the action of psychedelic therapy
Robin Carhart-Harris, Richard Zeifman, Lorenzo Pasquini, Bijurika Nandi, Cyrus Rohani-Shukla, Shayam Suseelan, Pedro A. M. Mediano, Fernando E. Rosas, Christopher Timmermann, Hannes Kettner, Patrick A. McConnell
May 13, 2026 preprint DOI: 10.31234/osf.io/wzh7b_v1 via OpenAlex
Summary
AI-generated from the abstractThe paper argues that the term 'plasticity' in neuroscience refers to induced changes in brain function or structure, which differs from the dictionary definition of plasticity as the ability to be shaped or molded. Many biomarkers of neuroplasticity actually index processes that bias phenotypic canalization, the opposite of phenotypic plasticity, creating a paradox. The authors question extrapolating from these biomarkers to improved mental health, as the relationship is context dependent. They propose a new construct, 'mediational and recalibrative plasticity' (MR-P), which aligns with plasticity proper and can describe and predict phenotypic changes relevant to mental health.
Study at a glance
| Characteristics | Theoretical or philosophical paper |
|---|---|
| Topics | Neuroplasticity |
| Keywords | Action physics Context archaeology Meaning existential Construct python library |
| Key finding | The common use of 'plasticity' to describe neuroplastic phenomena conflates assays of evoked brain changes with plasticity proper, and the authors propose a new construct, MR-P, that aligns with plasticity proper. |
Abstract
First-line dictionary definitions of ‘plasticity’ describe it as the ability (of a thing) to be shaped or molded; we call this ‘plasticity proper’. In neuroscience, however, ‘neural plasticity’ or ‘neuroplasticity’ is defined as an induced change in brain function or structure. These two plasticities are not the same. Several (but not all) popular biomarkers of neuroplasticity index part of an evoked process, often linked to learning. Paradoxically, these processes often bias phenotypic canalization, the opposite of phenotypic plasticity. Recognizing this paradox puts into question the custom of using ‘plasticity’ as a shorthand for such neuroplastic phenomena, an overgeneralization that risks conflating assays of evoked brain changes with plasticity proper. We also question extrapolating from any biomarker of neuroplasticity (whether it be aligned with plasticity proper or not) to improved mental health. The relationship between the two is (naturally) context dependent. As a resolution, we propose a new construct ‘mediational and recalibrative plasticity’ (MR-P) and show how markers of it can describe and predict examples of phenotypic change, including psychological states and traits relevant to mental health. In contrast to many markers of neuroplasticity, MR-P is aligned with plasticity proper.