A new neuroscience paper on how the brain represents conscious and unconscious content is making the rounds, and it’s drawn a notable reaction from one of the field’s more outspoken figures. Anesthesiologist Stuart Hameroff has responded to the study by arguing that its results are — in his words — “possibly” consistent with only one existing theory of consciousness: Orchestrated Objective Reduction, or Orch OR, the quantum theory of consciousness he developed with physicist Roger Penrose.
The paper Hameroff is reacting to
The study, posted as a preprint by Janis Hesse, Doris Tsao, and colleagues at UC Berkeley, Caltech, and Princeton, recorded from large populations of neurons in monkey inferotemporal and prefrontal cortex using Neuropixels probes while the animals viewed a classic illusion called binocular flash suppression — a setup where one image is consciously seen while a second, different image stays physically present but is suppressed from awareness.
The researchers found that neural activity doesn’t settle into one stable pattern representing “what’s conscious.” Instead, it rapidly alternates — about 15 times a second, or roughly every 60 milliseconds — between a state that purely and accurately represents the consciously seen image, and a state that purely and accurately represents the suppressed, unseen one. The same neurons do both jobs, just at different moments. This alternation was fast enough, and distinct enough from the slow seconds-long perceptual switches studied in older rivalry experiments, that the authors describe it as “temporal multiplexing” — the brain timesharing a single population of cells between conscious and unconscious content, rather than keeping them in separate places.
Stuart Hameroff and ORCH-OR
Stuart Hameroff is a professor of anesthesiology and psychology at the University of Arizona, where he also directs the university’s Center for Consciousness Studies. He has spent much of his career studying anesthesia — specifically, trying to figure out exactly what anesthetic drugs do inside neurons to switch off consciousness while leaving the rest of brain activity largely intact. That line of work led him, in the late 1980s and early 1990s, to a collaboration with the mathematical physicist Roger Penrose, co-author of landmark work on black holes and general relativity, and the two went on to co-develop one of the most debated theories of consciousness in modern science.
Orchestrated Objective Reduction proposes that consciousness arises from quantum processes occurring inside microtubules — hollow, tube-shaped protein structures found in the internal skeleton of every neuron (and, in fact, of nearly every cell in the body). The theory holds that these microtubules can sustain quantum superpositions, and that consciousness corresponds to specific moments when those quantum states collapse, or “objectively reduce,” in a way that is orchestrated by the biological structure of the neuron rather than happening randomly. Penrose’s contribution ties this collapse to his own ideas about quantum gravity, arguing that it occurs when the mass-energy difference between superposed states crosses a threshold linked to the fundamental structure of spacetime itself.
Orch OR has always been a minority position. Most neuroscientists have argued that the brain is far too warm, wet, and noisy an environment for delicate quantum superpositions to survive long enough to matter for cognition, and that there’s no solid empirical evidence microtubules do what the theory requires of them. The theory has nonetheless persisted for over two decades, repeatedly revised, and has an enthusiastic following in some corners of physics and consciousness research.
Hameroff’s argument
In his reaction to the paper, Hameroff calls the results “a real breakthrough,” and argues that the specific type of layered, sequential processing — sensory information moving from primary visual cortex (V1) forward into frontal cortex in a cascade of progressively slower events — is something Orch OR specifically predicts. In his account, information is represented “holographically” within microtubules inside each neuron, which he says explains how the same neurons can carry both a selected, conscious signal and an unselected, nonconscious signal simultaneously — precisely the dual role the new paper’s neurons were shown to play. The slowing cascade of processing, in his framework, comes from interference between faster gigahertz- and megahertz-range oscillations inside the microtubule lattice, eventually culminating in what he calls a “conscious moment.”
Hameroff also points to what he considers a second point in Orch OR’s favor: its account of general anesthesia. Since Orch OR locates the seat of consciousness in quantum states inside microtubules, it predicts that anesthetic drugs work by selectively interfering with microtubule quantum processes — directly tying the theory back to the phenomenon Hameroff has studied clinically for decades — rather than, as most pharmacology holds, primarily acting on ion channels and neurotransmitter receptor proteins embedded in neuronal membranes.
It’s worth noting that this is Hameroff’s own interpretation of the findings, not a conclusion the paper’s authors draw themselves. The Hesse/Tsao study doesn’t test, mention, or make any claims about quantum processes, microtubules, or Orch OR; it’s a conventional electrophysiology paper that frames its results around competing mainstream theories like Global Neuronal Workspace, Integrated Information Theory, and Recurrent Processing Theory — all of which also claim to accommodate temporal, dynamic accounts of consciousness, and none of which require any physics beyond standard neurobiology.
Where things stand
Orch OR remains a minority view, and the broader neuroscience and physics communities have long been skeptical of its core claim that biologically relevant quantum coherence can survive inside a warm neuron for anywhere near the timescales involved in cognition. The new paper’s authors, for their part, frame their own finding — fast alternation between conscious and suppressed representations within standard spiking activity — as a question for existing, non-quantum theories of consciousness to answer, specifically which of them can explain why only some of these rapid micro-epochs get “selected” for awareness and others don’t.
Whether that selection mechanism turns out to live in classical network dynamics, as most of the field expects, or somewhere stranger, as Hameroff continues to argue, is likely to stay an open and contested question for a while yet.