University of Arizona, Tucson, USA
Anesthesia, Consciousness, Bohm and Penrose
David Bohm believed the brain utilized quantum mechanisms, and that conscious thought was distributed and non-local. Roger Penrose has proposed that consciousness involves quantum state reductions linked to an objective threshold intrinsic to spacetime geometry (objective reduction, ‘OR’). For either, the brain must sustain quantum coherent superpositions long enough for cognitive functions. How can this happen? Perhaps the best approach is to pinpoint the action of anesthetic gases which selectively block consciousness, sparing non-conscious brain activities. In the 19th century a group of gases with diverse chemical structures were found to reversibly render humans and animals immobile, unresponsive and unconscious. These disparate ‘anesthetic’ gases bind by weak, quantum interactions known as van der Waals London dipole forces. Hans Meyer (1899) and Charles Overton (1901) found that anesthetic potency correlated with binding in non-polar, lipid-like regions (the ‘Meyer-Overton correlation’). Subsequent work by Nick Franks and Bill Lieb (1984) showed anesthetics acted in such regions inside proteins, e.g. ‘pi resonance’ electron clouds of aromatic amino acid rings. Which proteins? Although membrane receptor and ion channel proteins were long thought to mediate anesthesia (and consciousness), evidence now points instead to microtubules inside neurons. Polymers of the protein tubulin, microtubules regulate neuronal synapses and membrane states, and have resonant oscillations in terahertz, gigahertz, megahertz and kilohertz. In Craddock et al (2017), we used computer modeling and quantum chemistry to simulate collective quantum dipole oscillations of pi resonance clouds of all 86 aromatic rings in tubulin. We found a spectrum of terahertz oscillation frequencies which included a prominent ‘common mode’ peak at 613 terahertz (in the visible blue light spectrum, but existing internally to the system without photoexcitation). We then re-simulated the collective tubulin quantum oscillations with each of 8 anesthetic gases, and 2 gases which bind in non-polar, pi resonance regions but do not cause anesthesia (‘non-anesthetics’). We found that all 8 anesthetics abolished the 613 terahertz peak proportional to their potency, and that non-anesthetics had no effect, suggesting anesthetics prevent consciousness by dampening terahertz quantum oscillations in brain microtubules, supporting either a Bohmian approach, and/or the Penrose-Hameroff ‘Orch OR’ theory. In Orch OR, consciousness occurs due to ‘orchestrated’ (‘Orch’) quantum states and objective reductions (‘OR’) in microtubules which resonate through a multi-scale vibrational hierarchy to membrane and synaptic activities in hertz. A ‘Meyer-Overton quantum underground’ appears to support quantum states and brain function leading to consciousness.
Reference: Craddock TJA, Kurian P, Preto J, Sahu K, Hameroff SR, Klobukowski M, Tuszynski JA (2017) Anesthetic alterations of collective terahertz oscillations in tubulin correlate with clinical potency: Implications for anesthetic action and post-operative cognitive dysfunction. Nature – Scientific Reports 7(1): 9877. DOI:10.1038/s41598-017-09992-7.