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Orchestrated reduction of quantum coherence in brain microtubules: A model for consciousness

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  • Hameroff, Stuart
  • Penrose, Roger

Abstract

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-collapse” (objective reduction: OR - Penrose, 1994) are essential for consciousness, and occur in cytoskeletal microtubules and other structures within each of the brain's neurons. The particular characteristics of microtubules suitable for quantum effects include their crystal-like lattice structure, hollow inner core, organization of cell function and capacity for information processing. We envisage that conformational states of microtubule subunits (tubulins) are coupled to internal quantum events, and cooperatively interact (compute) with other tubulins. We further assume that macroscopic coherent superposition of quantum-coupled tubulin conformational states occurs throughout significant brain volumes and provides the global binding essential to consciousness. We equate the emergence of the microtubule quantum coherence with pre-conscious processing which grows (for up to 500 ms) until the mass-energy difference among the separated states of tubulins reaches a threshold related to quantum gravity. According to the arguments for OR put forth in Penrose (1994), superpositioned states each have their own space-time geometries. When the degree of coherent mass-energy difference leads to sufficient separation of space-time geometry, the system must choose and decay (reduce, collapse) to a single universe state. In this way, a transient superposition of slightly differing space-time geometries persists until an abrupt quantum → classical reduction occurs. Unlike the random, “subjective reduction” (SR, or R) of standard quantum theory caused by observation or environmental entanglement, the OR we propose in microtubules is a self-collapse and it results in particular patterns of microtubule-tubulin conformational states that regulate neuronal activities including synaptic functions. Possibilities and probabilities for post-reduction tubulin states are influenced by factors including attachments of microtubule-associated proteins (MAPs) acting as “nodes” which tune and “orchestrate” the quantum oscillations. We thus term the self-tuning OR process in microtubules “orchestrated objective reduction” (“Orch OR”), and calculate an estimate for the number of tubulins (and neurons) whose coherence for relevant time periods (e.g. 500 ms) will elicit Orch OR. In providing a connection among (1) pre-conscious to conscious transition, (2) fundamental space-time notions, (3) non-computability, and (4) binding of various (time scale and spatial) reductions into an instantaneous event (“conscious now”), we believe Orch OR in brain microtubules is the most specific and plausible model for consciousness yet proposed.

Suggested Citation

  • Hameroff, Stuart & Penrose, Roger, 1996. "Orchestrated reduction of quantum coherence in brain microtubules: A model for consciousness," Mathematics and Computers in Simulation (MATCOM), Elsevier, vol. 40(3), pages 453-480.
  • Handle: RePEc:eee:matcom:v:40:y:1996:i:3:p:453-480
    DOI: 10.1016/0378-4754(96)80476-9
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    Cited by:

    1. Tanaka, Shigenori & Umegaki, Toshihito & Nishiyama, Akihiro & Kitoh-Nishioka, Hirotaka, 2022. "Dynamical free energy based model for quantum decision making," Physica A: Statistical Mechanics and its Applications, Elsevier, vol. 605(C).
    2. Markus A Maier & Vanessa L Buechner & Moritz C Dechamps & Markus Pflitsch & Walter Kurzrock & Patrizio Tressoldi & Thomas Rabeyron & Etzel Cardeña & David Marcusson-Clavertz & Tatiana Martsinkovskaja, 2020. "A preregistered multi-lab replication of Maier et al. (2014, Exp. 4) testing retroactive avoidance," PLOS ONE, Public Library of Science, vol. 15(8), pages 1-18, August.
    3. Mika Suojanen, 2019. "Conscious Experience and Quantum Consciousness Theory: Theories, Causation, and Identity," E-LOGOS, Prague University of Economics and Business, vol. 2019(2), pages 14-34.
    4. Yu, Jiangbo Gabriel & Jayakrishnan, R., 2018. "A quantum cognition model for bridging stated and revealed preference," Transportation Research Part B: Methodological, Elsevier, vol. 118(C), pages 263-280.
    5. Shirmovsky, S.Eh. & Shulga, D.V., 2021. "Quantum relaxation effects in Microtubules," Physica A: Statistical Mechanics and its Applications, Elsevier, vol. 582(C).
    6. Shirmovsky, S.Eh. & Shulga, D.V., 2023. "Quantum relaxation processes in microtubule tryptophan system," Physica A: Statistical Mechanics and its Applications, Elsevier, vol. 617(C).
    7. Chris Fields, 2015. "How small is the center of science? Short cross-disciplinary cycles in co-authorship graphs," Scientometrics, Springer;Akadémiai Kiadó, vol. 102(2), pages 1287-1306, February.
    8. Shirmovsky, S.Eh. & Shulga, D.V., 2019. "Microtubules lattice equal-frequency maps: The dynamics of relief changes in dependence on elastic properties, tubulins’ dipole–dipole interaction and viscosity," Physica A: Statistical Mechanics and its Applications, Elsevier, vol. 534(C).

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