Stuart Hameroff

The University of Arizona | UA · Departments of Anesthesiology and Psychology

In neuroscience, the flow of time is a conscious experience produced by the brain. But in physics, time is either a process, or a dimension in four-dimensional spacetime geometry. Could all three explanations be correct? The Penrose–Hameroff ‘Orch OR’ theory suggests consciousness is a sequence of discrete, irreversible quantum state reductions occ...

Consciousness and quantum mechanics are two mysteries in our times. A careful and thorough examination of possible connections between them may help unravel these two mysteries. On the one hand, an analysis of the conscious mind and psychophysical connection seems indispensable in understanding quantum mechanics and solving the notorious measuremen...

Viewing the brain as a complex computer of simple neurons cannot account for consciousness nor essential features of cognition. Single cell organisms with no synapses perform purposeful intelligent functions using their cytoskeletal microtubules. A new paradigm is needed to view the brain as a scale-invariant hierarchy extending both upward from th...

The SARS-CoV-2 virus invades and replicates within host cells by “hijacking” biomolecular machinery, gaining control of the microtubule cytoskeleton. After attaching to membrane receptors and entering cells, the SARS-CoV-2 virus co-opts the dynamic intra-cellular cytoskeletal network of microtubules, actin, and the microtubule-organizing center, en...

Transcranial focused ultrasound (tFUS) is an emerging method for non-invasive neuromodulation akin to transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). tFUS offers several advantages over electromagnetic methods including high spatial resolution and the ability to reach deep brain targets. Here we describe...

Consciousness and reality are related through the “measurement problem” in quantum mechanics, i.e., why we do not consciously perceive particles as quantum superpositions of multiple possibilities, as they appear to be when unobserved, but rather perceive them consciously as being in definite states or locations. Quantum pioneers Niels Bohr, John v...

The mechanism by which anesthetic gases selectively prevent consciousness and memory (sparing non-conscious brain functions) remains unknown. At the turn of the 20th century Meyer and Overton showed that potency of structurally dissimilar anesthetic gas molecules correlated precisely over many orders of magnitude with one factor, solubility in a no...

It was once purported that biological systems were far too warm and wet to support quantum phenomena mainly due to thermal effects disrupting quantum coherence. However recent experimental results and theoretical analyses have shown that thermal energy may assist, rather than disrupt, quantum coherence, especially in the dry hydrophobic interiors o...

This paper presents a historical perspective on the development and application of quantum physics methodology beyond physics, especially in biology and in the area of consciousness studies. Quantum physics provides a conceptual framework for the structural aspects of biological systems and processes via quantum chemistry. In recent years individua...

In the 20 years of the Journal of Consciousness Studies (JCS) I've been deeply involved with the conference series 'Toward a Science of Consciousness' (TSC), and the 'orchestrated objective reduction'(Orch OR) theory of consciousness with Sir Roger Penrose. Thanks in large part to JCS and TSC, an interdisciplinary field of Consciousness Studies has...

Cognitive decisions are best described by quantum mathematics. Do quantum information devices operate in the brain? What would they look like? Fuss and Navarro () describe quantum lattice registers in which quantum superpositioned pathways interact (compute/integrate) as 'quantum walks' akin to Feynman's path integral in a lattice (e.g. the 'Feynma...

TUS delivered to the right frontal cortex increasedpositive affect, replicating effects in the transcranialmagnetic stimulation (TMS) literature in healthy controls

The nature of consciousness, the mechanism by which it occurs in the brain, and its ultimate place in the universe are unknown. We proposed in the mid 1990's that consciousness depends on biologically 'orchestrated' coherent quantum processes in collections of microtubules within brain neurons, that these quantum processes correlate with, and regul...

The "Orch OR" theory suggests that quantum computations in brain neuronal dendritic-somatic microtubules regulate axonal firings to control conscious behavior. Within microtubule subunit proteins, collective dipoles in arrays of contiguous amino acid electron clouds enable "quantum channels" suitable for topological dipole "qubits" able to physical...

Conscious "free will" is problematic because (1) brain mechanisms causing consciousness are unknown, (2) measurable brain activity correlating with conscious perception apparently occurs too late for real-time conscious response, consciousness thus being considered "epiphenomenal illusion," and (3) determinism, i.e., our actions and the world aroun...

The cytoskeleton is essential to cell morphology, cargo trafficking, and cell division. As the neuronal cytoskeleton is extremely complex, it is no wonder that a startling number of neurodegenerative disorders (including but not limited to Alzheimer's disease, Parkinson's disease and Huntington's disease) share the common feature of a dysfunctional...

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Alzheimer's disease (AD) is the most common form of dementia in the elderly. Hallmark AD neuropathology includes extracellular amyloid plaques composed largely of the amyloid-β protein (Aβ), intracellular neurofibrillary tangles (NFTs) composed of hyper-phosphorylated microtubule-associated protein tau (MAP-tau), and microtubule destabilization. Ea...

Memory is attributed to strengthened synaptic connections among particular brain neurons, yet synaptic membrane components are transient, whereas memories can endure. This suggests synaptic information is encoded and 'hard-wired' elsewhere, e.g. at molecular levels within the post-synaptic neuron. In long-term potentiation (LTP), a cellular and mol...

The concept of consciousness existing outside the body (e.g. near-death and out-of body experiences, NDE/OBEs, or after death, indicative of a ‘soul’) is a staple of religious traditions, but shunned by conventional science because of an apparent lack of rational explanation. However conventional science based entirely on classical physics cannot a...

The great potential for building molecular scale machines and other structures was first noted by Richard Feynman (1960). He also proposed the development of tools to construct nanoscale mechanisms and devices. The range of technology that he proposed is now called nanotechnology, a term coined by Taniguchi (1974). Emergence of STM and related tech...

The human brain is able to perform a number feats that researchers have not been able to replicate in artificial systems. Unsolved questions include: Why are we conscious and how do we process visual information from the input stimulus right down to the individual action. We have created a computational model of visual information processing. A net...

Cognitive brain functions, for example, sensory perception, motor control and learning, are understood as computation by axonal-dendritic chemical synapses in networks of integrate-and-fire neurons. Cognitive brain functions may occur either consciously or nonconsciously (on "autopilot"). Conscious cognition is marked by gamma synchrony EEG, mediat...

Learning, memory and long-term potentiation (LTP) are supported by factors including post-synaptic calcium ion flux activating and transforming the hexagonal calcium-calmodulin kinase II (CaMKII) holoenzyme. Upon calcium-induced activation, up to six kinase domains extend upward, and up to six kinase domains extend downward from the CaMKII associat...

The brain is viewed as a computer in which sensory processing, control of behavior and other cognitive functions emerge from ‘neurocomputation’ in parallel networks of perceptron-like neurons. In each neuron, dendrites receive and integrate synaptic inputs to a threshold for axonal firing as output — ‘integrate-and-fire’. Neurocomputation in axonal...

Cognitive brain functions including sensory processing and control of behavior are understood as "neurocomputation" in axonal-dendritic synaptic networks of "integrate-and-fire" neurons. Cognitive neurocomputation with consciousness is accompanied by 30- to 90-Hz gamma synchrony electroencephalography (EEG), and non-conscious neurocomputation is no...

In their article, Is the Brain a Quantum Computer,? Litt, Eliasmith, Kroon, Weinstein, and Thagard (2006) criticize the Penrose-Hameroff "Orch OR" quantum computational model of consciousness, arguing instead for neurocomputation as an explanation for mental phenomena. Here I clarify and defend Orch OR, show how Orch OR and neurocomputation are com...

Conference Report on ASSC 11, Las Vegas 2007

Consciousness is generally considered to emerge from synaptic computation among brain neurons, but this approach cannot account for its critical features. The Penrose-Hameroff “Orch OR” model suggests that consciousness is a sequence of quantum computations in microtubules within brain neurons, shielded from decoherence to reach threshold for objec...

Propierties which define living systems at the molecular level include self-organization, communication, adaptive behavior and computation. Logic functions may implement these propierties in biomolecules and therefore may be essential to living systems. Several logic systems from Boolean to Spencer-Brown algebra have been suggested to be applicable...

Malignant cells are characterized by abnormal segregation of chromosomes during mitosis ("aneuploidy"), generally considered a result of malignancy originating in genetic mutations. However, recent evidence supports a century-old concept that maldistribution of chromosomes (and resultant genomic instability) due to abnormalities in mitosis itself i...

Activities in living cells are performed by protein conformational dynamics which in turn are governed by quantum mechanical van der Waals London forces in intra-protein "hydrophobic" pockets. In assemblies of proteins with periodic lattice geometry such as cytoskeletal actin and microtubules (as well as ordered water on their surfaces), Bose-Einst...

What is time? St. Augustine remarked that when no one asked him, he knew what time was; however when someone asked him, he did not. Is time a process which flows? Is time a dimension in which processes occur? Does time actually exist?

What is consciousness? Some philosophers have contended that "qualia," or an experiential medium from which consciousness is derived, exists as a fundamental component of reality. Whitehead, for example, described the universe as being comprised of "occasions of experience." To examine this possibility scientifically, the very nature of physical re...

The Penrose-Hameroff (`Orch OR') model of quantum computation in brain microtubules has been criticized as regards the issue of environmental decoherence. A recent report by Tegmark finds that microtubules can maintain quantum coherence for only $10^{-13}$ s, far too short to be neurophysiologically relevant. Here, we critically examine the assumpt...

Technological computation is entering the quantum realm, focusing attention on biomolecular information processing systems such as proteins, as presaged by the work of Michael Conrad. Protein conformational dynamics and pharmacological evidence suggest that protein conformational states-fundamental information units ('bits') in biological systems-a...

A theoretical approach relying on quantum computation in microtubules within neurons can potentially resolve the enigmatic features of visual consciousness, but raises other questions. For example, how can delicate quantum states, which in the technological realm demand extreme cold and isolation to avoid environmental 'decoherence', manage to surv...

What is consciousness? Conventional approaches see it as an emergent property of complex interactions among individual neurons; however these approaches fail to address enigmatic features of consciousness. Accordingly, some philosophers have contended that “qualia,” or an experiential medium from which consciousness is derived, exists as a fundamen...

As presently implemented, the neuron doctrine (ND) portrays the brain's neurons and chemical synapses as fundamental components in a computer-like switching circuit, supporting a view of brain = mind = computer. However, close examination reveals individual neurons to be far more complex than simple switches, with enormous capacity for intrace...

1. A consensus view holds that anesthetics act by van der Waals forces in hydrophobic pockets of select brain proteins to ablate consciousness. 2. What is consciousness? Enigmatic features of consciousness (e.g. 'qualia', binding, non-computability, pre-conscious-->conscious transition, nondeterministic free will) may be explained by the occurrence...

Potential features of quantum computation could explain enigmatic aspects of consciousness. The Penrose—Hameroff model (orchestrate objective reduction: ‘Orch OR’) suggests that quantum superposition and a form of quantum computation occur in microtubules—cylindrica protein lattices of the cell cytoskeleton within the brain's neurons. Microtubules...

Age-old battle lines over the puzzling nature of mental experience are shaping a modern resurgence in the study of consciousness. On one side are the long-dominant `physicalists' who view consciousness as an emergent property of the brain's neural networks. On the alternative, rebellious side are those who see a necessary added ingredient: proto-co...

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Most views of neuro-cognitive function including the ANN analogy, assume that modification of efficacy or sensitivity of existing synapses — referred to as synaptic strength — is the brain's primary mechanism for information storage and transfer. Many factors influence biological strength, however in artificial neural networks the analogous interco...

Features of consciousness difficult to understand in terms of conventional neuroscience have evoked application of quantum theory, which describes the fundamental behavior of matter and energy. In this paper we propose that aspects of quantum theory (e.g. quantum coherence) and of a newly proposed physical phenomenon of quantum wave function “self-...

The quality of red-fleshed grapefruit after exposure to a constant (46°C for 300 min), or stepped (40°C for 120 min, 50°C for 90 min, and 52°C until the fruit center temperature is 48°C) temperature, forced-air quarantine heat treatment was evaluated. Grapefruit exposed to either heat treatment had lower titratable acidity and slightly better flavo...

Cytoskeletal microtubules structurally organize interiors of living eukaryotic cells. As polymers of subunit proteins (“tubulin”), which are each dipoles, microtubules are thus lattices of oriented dipoles. In general, three types of arrangements of dipoles in lattices may occur: (i) random, (ii) ferroelectric (parallel-aligned) and (iii) an interm...

Grush and Churchland (1995) attempt to address aspects of the proposal that we have been making concerning a possible physical mechanism underlying the phenomenon of consciousness. Unfortunately, they employ arguments that are highly misleading and, in some important respects, factually incorrect. Their article `Gaps in Penrose's Toilings' is addre...

This paper introduces the ideas of neural networks in the context of currently recognized cellular structures within neurons. Neural network models and paradigms require adaptation of synapses for learning to occur in the network. Some models of learning paradigms require information to move from axon to dendrite. This motivated us to examine the p...

'Laser-like,' long-range coherent quantum phenomena may occur biologically within cytoskeletal microtubules. This paper presents a theoretical prediction of the occurrence in biological media of the phenomena which we term 'superradiance' and 'self-induced transparency'. Interactions between the electric dipole field of water molecules confined wit...

The paper begins with a general introduction to the nature of human consciousness and outlines several different philosophical approaches. A critique of traditional reductionist and dualist positions is offered and it is suggested that consciousness should be viewed as an emergent property of physical systems. However, although consciousness has it...

Fullerene C60 was purified and imaged utilizing scanning tunneling microscopy (STM) in a constant current mode. By fixing the fullerenes on the substrate (“frozen state” — no movement or rotation), direct imaging of C60 with atomic resolution was possible, showing pentagon and hexagon carbon rings of C60. A high voltage STM pulse of C60 appears to...

Adaptive behaviors and dynamic activities within living cells are organized by the cytoskeleton: intracellular networks of interconnected protein polymers which include microtubules (MTs), actin, intermediate filaments, microtubule associated proteins (MAPs) and other protein structures. Cooperative interactions among cytoskeletal protein subunit c...

C60 was purified and imaged utilizing scanning tunnelling microscopy (STM) in a constant current mode. By fixing the Fullerenes on the substrate (“frozen state” - no movement or rotation), direct imaging of C60 with atomic resolution was possible, showing one pentagon and one hexagon carbon ring of C60.

The authors propose a set of models for computing within cytoskeletal filamentous polymers: microtubules (MTs), actin, intermediate filaments and cross-bridging microtubule-associated proteins (MAPs). Signals and information may be represented and transmitted via propagated conformational changes of these structures' subunits which locally interact...

The structure and conformational dynamic changes that occur in cytoskeletal proteins within living cells and evidence for their participation in computational processing are described. The role of cellular automata, in which lattice subunits with discrete states interact only with nearest neighbors, in molecular computing is discussed. Simple rules...

Cytoskeletal signaling provides a medium for internal neuronal signaling that could play a key role in biological learning. Signaling within a neuron along microtubules is plausible according to a number of theoretical models and experimental observations. If used by biological neurons, this type of signaling would provide the missing link for the...

A possible role for phonon excitations of the cytoskeleton in intraneuronal pattern recognition and learning is discussed. Biophysical support is presented for molecular implementation of adaptive resonant theory neural network principles. Relations between pattern recognition by neural network and symmetry breaking second order phase transitions a...

The cytoskeletal intraneuronal structure and some candidate mechanisms for signaling within nerve cells are described. Models were developing for the interaction of the cytoskeleton with cell membranes, synapses, and an internal signaling model that renders back-error propagation biologically plausible. Orientation-selective units observed in the p...

In this paper we present scanning tunneling microscopy images of cytokeratin proteins and a monoclonal anti‐cytokeratin IgG antibody bound to their carboxyl terminal end. The images are consistent with current models of cytokeratin assembly inferred from biochemical analysis, electron microscopy evaluation of disintegrating cytokeratin filaments, a...

A computer-based, integrated monitor system was designed and utilized to collect and interactively manage physiologic data (13 variables and 3 waveforms) from six routinely used operating room monitors. Various approaches were developed to reduce false alarms, classify waveforms, and recognize events. False alarms: false alarms in ECG heart rate de...

Scanning tunneling microscopy (STM) is used to image fine surface detail of cytokeratin α‐helical protein. Resolution of molecular structure increased with extended exposure of partially purified cytokeratin protein to cold temperatures from 12 to 48 h. Surface of a cytokeratin tetrameric units resolved by STM depicts 2 nm diam wraps of cytokeratin...

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Interiors of neurons are occupied and organized by dynamic networks, called cytoskeletons, of protein polymers. These biomolecular networks (microtubules, or MT, actin, intermediate filaments, centrioles, etc.) are coupled to membrane events and regulate cellular activities, including synaptic plasticity. Models of purposeful behavior in the cytosk...

“Neural network” models of brain function assume neurons and their synaptic connections to be the fundamental units of information processing, somewhat like switches within computers. However, neurons and synapses are extremely complex and resemble entire computers rather than switches. The interiors of the neurons (and other eucaryotic cells) are...

Direct STM observation of native biomolecules has proven feasible. In this study we have used STM to image two filamentous protein components of the intracellular cytoskeleton: microtubules (MT) and intermediate filaments (IF). MT are 25 nm diameter cylinders comprised of 13 ‘‘protofilaments’’ which are linear chains of 8 nm × 4 nm × 4 nm ‘‘dimer’’...

The cytoskeleton, a class of protein polymers including microtubules (MTs), intelligently organizes the interiors of living cells. Interconnected microtubules have been modeled as adaptive networks in which emergent computation occurs. The model comprises parallel networks of MTs variably interconnected by filamentous proteins by means of MT-associ...

An investigation of the electroencephalogram (EEG) under anesthetic sleep conditions was conducted to evaluate dimensionality as an EEG-derived parameter that might reflect complex brain dynamics in a clinically useful way. Dimensional analysis of EEG has resulted in reported apparent dimensions ranging from 2 to 9. The homogeneity of the present r...

To observe surface topography of microtubules, we have applied scanning tunneling microscopy (STM), which can image metal and semiconductive surfaces with atomic resolution. Isolated microtubules fixed in 0.1% glutaraldehyde in reassembly buffer containing 0.8 M glycerol were imaged in air on a graphite substrate. The presence of microtubules in so...