Psychedelic Therapy’s Role in Hearing Disorders

A foundational misunderstanding of the term “plasticity” in neuroscience could be obscuring the search for better treatments for conditions like tinnitus, hyperacusis, and misophonia. A new theoretical paper by researchers Robin Carhart-Harris, Richard Zeifman, and Lorenzo Pasquini argues that the field has conflated two distinct concepts, potentially leading research down unhelpful paths.

The Plasticity Paradox: When Brain Change Means Rigidity

The core of the argument lies in a linguistic and conceptual confusion. In its primary dictionary definition, “plasticity proper” (PP) refers to a material’s ability to be shaped or molded—a state of potential adaptability. In neuroscience, however, “neuroplasticity” has become a catch-all term for any induced change in brain function or structure.

Carhart-Harris and colleagues point out a critical paradox: many popular biomarkers of neuroplasticity, such as long-term potentiation (LTP) or the strengthening of specific neural pathways, actually index processes that lead to canalization. Canalization is the process by which a system becomes more fixed and resistant to change, like a river carving a deep, unalterable channel. “What is often labelled ‘neuroplasticity’ in the literature is, ironically, a process that reduces plasticity proper,” the authors write. This is a significant problem for interpreting research, especially in hearing disorders where maladaptive, rigid brain patterns are often the issue.

Why This Distinction Matters for Hearing and Sound Sensitivity

For patients with chronic tinnitus or hyperacusis, the brain’s auditory and emotional networks can become stuck in a canalized state. The persistent perception of sound (tinnitus) or a heightened, aversive reaction to normal sound (hyperacusis/misophonia) reflects a loss of adaptive flexibility. If researchers use assays that measure canalization but call it “plasticity,” they risk misidentifying what a successful treatment should achieve.

A treatment that simply induces more change in an already maladaptive network might not be helpful. The goal, instead, is to restore the brain’s capacity for mediational and recalibrative plasticity (MR-P)—the new construct proposed by the authors. MR-P describes a brain state that can mediate between stimuli and responses and recalibrate its own settings, moving it closer to the true definition of plasticity as an adaptable, moldable system. This aligns with therapeutic goals in sound therapy for hyperacusis or certain neuromodulation approaches, which aim to soften rigid neural responses.

Questioning the Leap from Biomarker to Wellbeing

The paper also issues a strong warning against a common assumption in both popular science and some clinical research: that a measured change in a “neuroplasticity” biomarker automatically translates to improved mental health or symptom relief. The relationship is not guaranteed. “The link between any biomarker of neuroplasticity and improved mental health is, logically, context dependent,” the authors state.

For example, a brain scan might show that a new drug alters auditory cortex activity. This change could theoretically make tinnitus and sleep disturbance worse, better, or have no effect, depending on the nature and context of the change. The outcome depends on whether the intervention promotes maladaptive canalization or beneficial MR-P. This is a vital consideration for evaluating novel treatments, including those involving psychedelic-assisted therapy, which are often hypothesized to work by increasing brain plasticity.

Practical Implications for Research and Treatment

The practical implications of this theoretical work are substantial. First, it calls for greater precision in language. Researchers should specify whether they are measuring processes that lead to canalization or to true, adaptable plasticity (MR-P).

Second, it guides the search for better biomarkers. Instead of looking for any brain change, the focus should shift to finding markers of the brain’s capacity to change its own patterns of change—its recalibrative potential. This could involve measuring the flexibility of brain networks or the responsivity of systems that govern learning and unlearning. This refined approach could help explain why some individuals benefit from cognitive behavioral therapy while others do not, as it may relate to their baseline level of MR-P.

Finally, for patients and clinicians, it underscores that “promoting neuroplasticity” is not a specific or guaranteed therapeutic goal. The quality and direction of brain change matter more than change itself. Effective treatments for hearing-related distress will likely be those that specifically encourage the brain to become less rigid and more adaptively responsive, breaking the fixed patterns that maintain conditions like tinnitus and misophonia.

Source: Carhart-Harris, R., Zeifman, R., & Pasquini, L. (2026). The plasticity paradox in neuroscience: distinguishing canalization from mediational and recalibrative plasticity. Frontiers in Neuroscience. DOI: 10.3389/fnins.2026.1875339.