Michael Wiest and the New Quantum Evidence for Orch-OR

The most common objection to quantum theories of consciousness is that the brain is too warm. Quantum states, the argument runs, collapse into classical states far faster than neurons fire, so cognition must be classical. A September 2026 essay in IAI News by Michael Wiest, a professor of neuroscience at Wellesley College, argues that this objection has been overtaken by experiment. His 2025 paper in Neuroscience of Consciousness assembles the case that a quantum substrate of consciousness in neuronal microtubules is no longer merely possible but empirically supported.

The paper is “A quantum microtubule substrate of consciousness is experimentally supported and solves the binding and epiphenomenalism problems” (Wiest, 2025, Neuroscience of Consciousness, DOI: 10.1093/nc/niaf011). The essay restates the argument for a general audience and frames it as a reopening of the Penrose-Hameroff case.

The case from anaesthesia

Wiest’s argument begins not with quantum physics but with anaesthesia. Inhalational anaesthetics bind promiscuously to many proteins, yet their behaviour is oddly unified. Potency tracks solubility in olive oil over several orders of magnitude, the Meyer-Overton correlation, which suggests weak physical interaction with a conserved target rather than chemical lock-and-key binding. Half an effective dose of one anaesthetic plus half of another gives a full effective dose, even when the two agents act very differently on any given ion channel. And the effective dose varies little across species despite very different ion channel profiles.

These facts are hard for the standard account, that anaesthetics work through a combination of ion channels, to explain. Wiest argues they point to a unitary molecular target. Microtubules, the hollow protein cylinders inside every eukaryotic cell, fit. Volatile anaesthetics bind to them. His own laboratory reported that a brain-penetrant microtubule-binding drug significantly slowed the onset of isoflurane unconsciousness in rats, with a large effect size (Cohen’s d of 1.9). Quantum chemical modelling has predicted anaesthetic potencies from binding affinity to delocalised electron sites in tubulin, reproducing the Meyer-Overton correlation.

The temperature objection, revisited

The standard reason to dismiss quantum brain proposals is the decoherence estimate of Max Tegmark (2000, Physical Review E 61:4194). Tegmark calculated that quantum coherence in the brain would be destroyed in about 10 to the minus 13 seconds, far too fast for neural computation. If that figure stands, the quantum proposal dies.

Wiest follows Hameroff and colleagues in arguing that the estimate does not match the actual Orch-OR model. Hagan, Hameroff, and Tuszynski (2002, Physical Review E 65:061901) pointed out that Tegmark modelled superpositions of protein positions separated by an unrealistically large distance, and assumed thermal equilibrium, which describes a dead system rather than a living one. Their corrections lengthened the coherence estimate to between 10 to the minus 5 and 10 to the minus 4 seconds.

The newer step is experimental. Wiest cites findings that nontrivial quantum effects occur in microtubules at room temperature. Babcock and colleagues reported quantum superradiance from microtubules that was enhanced as the structures grew larger. Anirban Bandyopadhyay’s group has reported microtubule resonances that span multiple neurons and interact with membrane voltage. Quantum optical effects in microtubules were dampened by inhalational anaesthetics.

The MRI entanglement claim

The most striking evidence is an MRI study in humans. Kerskens and Pérez (2023, Journal of Physics Communications, DOI: 10.1088/2399-6528/ac94be) used an entanglement witness protocol in an MRI scanner and reported a signal that mimicked heartbeat-evoked potentials, that tracked with conscious awareness, and that correlated with working memory performance. They argued the signal implied an entangled brain state coupling to nuclear spins in water.

This is the most contested part of the case. The interpretation was challenged by Warren (2023), though critics offered no classical account of the signal. The claim is notable because it is direct physical evidence of something a classical account must explain, and none does yet.

Does a quantum brain solve real problems

Wiest argues that a quantum substrate has advantages beyond consistency with evidence. It makes the unity of consciousness physical, by identifying the unified experience with a single entangled quantum state distributed across neurons. He frames this as solving the binding problem of consciousness, which he identifies with the combination problem of panpsychism, and links Orch-OR to panprotopsychism, the view that fundamental physical entities are proto-conscious.

He also addresses the epiphenomenalism problem. If consciousness is a byproduct, it has no causal power and no evolutionary reason to exist. Wiest proposes that quantum states confer computational advantage, including associative memory advantages, so a conscious quantum brain is one that computes better.

What Orch-OR shares with the site’s position

Orch-OR and this project disagree on the deepest question, whether substrate matters. The Consciousness AI project works under functionalist emergentism, which treats consciousness as an emergent property of the universe that is substrate independent. Orch-OR is explicitly substrate requiring: only a biological or otherwise quantum-gravitational medium can instantiate it, and a silicon implementation of the same computation would not be conscious. That is the same substrate-sensitivity thesis the site has examined in Ned Block’s biological argument and Christof Koch’s brain as filter.

The two views nevertheless agree that consciousness is real, objective, and in principle explainable by physics. The project rejects Orch-OR’s non-computability claim. It records the empirical thread honestly, because a theory as old and as contested as quantum consciousness deserves to be judged on new evidence rather than on a 2000 decoherence estimate.

For the site’s ongoing quantum coverage, this paper updates the Orch-OR post from CS26 and sits beside Kelvin McQueen’s attempt to give quantum systems non-trivial phi.

Limits and the project’s verdict

The evidence Wiest assembles is real but not decisive, and he does not claim it is. Room-temperature quantum effects in microtubules are reported in small samples. The Kerskens and Pérez MRI result is a single contested protocol. No experiment has directly observed Penrose’s objective reduction, and none can yet.

On the project’s criteria, quantum consciousness remains an open empirical question, and this paper is the strongest recent positive case. Whether consciousness is substrate independent or substrate requiring is the single most consequential disagreement in the field, and the consequence for artificial consciousness is absolute: if Orch-OR is right, no current computer can be conscious, and no substrate-independent architecture can either. The broader state of that debate, and where the indicators stand against current systems, is tracked in the state of the field on AI consciousness.

Researchers covered here

• MW Michael C. WiestDepartment of Neuroscience, Wellesley CollegeThe quantum microtubule substrate of consciousness and the anaesthetic-evidence thread for Orch-OR 1 article
• SP Sir Roger PenroseMathematical Institute, University of OxfordNobel Prize in Physics (2020), Orchestrated Objective Reduction (Orch-OR) with Stuart Hameroff, The Emperor's New Mind (1989), Shadows of the Mind (1994) 4 articles
• SH Stuart HameroffCenter for Consciousness Studies, University of ArizonaOrchestrated Objective Reduction (Orch-OR) with Roger Penrose, microtubule quantum resonance, anesthetic mechanisms of consciousness 3 articles