Psychedelic Plasticity in Hearing Disorder Therapy

A new paper from a prominent neuropsychopharmacology research group challenges a core assumption in neuroscience: that all forms of neuroplasticity are fundamentally about the brain’s capacity for change. The authors argue that much of what is measured as “neuroplasticity” in research may actually reflect processes that make the brain *less* adaptable, a direct contradiction to the dictionary definition of plasticity as the ability to be shaped or molded.

The Plasticity Paradox: When “Change” Means Staying the Same

Led by Professor Robin Carhart-Harris, the team starts by making a critical distinction. “Plasticity proper” (PP) is the basic ability of a system to be shaped. In neuroscience, however, “neuroplasticity” is broadly defined as any induced change in brain function or structure. The authors point out that these are not the same thing. In fact, they can be opposites.

Many popular biomarkers of neuroplasticity—such as long-term potentiation (LTP) or certain patterns of brainwave synchronization—are part of evoked processes often linked to learning and memory. Paradoxically, these processes often lead to phenotypic canalization. This is a biological principle where development becomes more buffered against change, leading to stable traits. In essence, the brain uses these “neuroplastic” mechanisms to solidify pathways and make its responses more predictable and rigid. This is the opposite of being shapable or moldable.

Why This Matters for Hearing and Sensory Health

This conceptual confusion has direct implications for research into conditions like tinnitus, misophonia, and hyperacusis. For years, the hope has been that promoting “neuroplasticity” could help recalibrate maladaptive auditory and emotional pathways. Therapies like targeted sound therapy for hyperacusis or certain forms of cognitive training aim to induce beneficial brain change.

However, if the biomarkers we use to measure success are actually indexing canalization, we might be misunderstanding the mechanism. An intervention could appear to successfully induce “neuroplasticity” while actually reinforcing the very neural rigidity that maintains a condition like chronic tinnitus. This may help explain why some therapeutic approaches show inconsistent results. The assumption that more “plasticity” is always better is flawed.

The authors are clear: extrapolating from any biomarker of neuroplasticity directly to improved mental or sensory health is a logical overgeneralization. The relationship is entirely context-dependent. A change in a neural circuit could just as easily lock in a negative pattern as open a door to a positive one.

Introducing a More Precise Target: Mediational and Recalibrative Plasticity

To resolve this paradox, Carhart-Harris and colleagues propose a new, more precise construct: “mediational and recalibrative plasticity” (MR-P). Unlike the broad and often contradictory umbrella of neuroplasticity, MR-P is explicitly aligned with “plasticity proper.”

The goal of MR-P is to identify and measure the brain’s capacity for adaptive recalibration. It describes a system’s ability to mediate between internal states and external demands, and to recalibrate its responses in a way that increases behavioral and psychological flexibility. The authors demonstrate how markers of MR-P can better describe and predict true phenotypic plasticity—where the observable traits and states (like sound sensitivity or tinnitus distress) actually show beneficial change.

This reframing is particularly relevant for understanding how interventions might work. For instance, a therapy that reduces tinnitus-related sleep disturbance shouldn’t just show “changed brain activity.” It should show brain activity patterns consistent with MR-P—patterns that mediate a shift from a rigid, distressed state to a more flexible, regulated one. This concept also intersects with research on predictive brain networks in hearing disorders, where maladaptive predictions become canalized.

Practical Implications for Treatment and Research

This paper does not offer a simple new treatment. Instead, it provides a crucial conceptual tool for evaluating existing and future therapies. It urges clinicians and researchers to ask more specific questions:

• Is this intervention promoting simple neural change, or is it promoting adaptive recalibration (MR-P)?
• Are the biomarkers we’re using measuring flexibility, or are they measuring the brain locking into a pattern?
• Could some “effective” therapies work partly by reducing maladaptive plasticity (canalization) rather than increasing plasticity proper?

This shift encourages a move away from vague claims of “retraining the brain” toward a more rigorous investigation of the type of brain change being induced. For patients, it underscores that the goal of therapy is not just any change, but a specific recalibration toward greater flexibility and reduced distress. This principle of targeted recalibration is a common thread in other evidence-based approaches, such as the structured methods discussed in the evidence-based sleep hygiene guide on our partner site.

The work by Carhart-Harris, Zeifman, and Pasquini is a call for precision. By adopting the MR-P framework, research into tinnitus, misophonia, and hyperacusis can better identify the mechanisms that truly underlie recovery and resilience, separating them from neurological changes that may simply represent a different kind of stability.

Source: Carhart-Harris, R., Zeifman, R., & Pasquini, L. (2026). [Paper Title]. Frontiers in Neuroscience. doi:10.3389/fnins.2026.1875339