Specifics of Orch OR

In a proposal for the mechanism of consciousness, Roger Penrose and I suggested that microtubule (MT) quantum computations in neurons are orchestrated by synaptic inputs and MT-associated proteins (MAPs), and terminate (e.g. after 25ms, 40Hz) by Roger's objective reduction (OR) mechanism. Hence, the model is known as orchestrated objective reduction, Orch OR. Complete details may be found in Penrose and Hameroff [174], Hameroff and Penrose [89, 90] and Hameroff [91]. The key points are:

1. Conformational states of tubulin protein subunits within dendritic MTs interact with neighbor tubulin states by dipole coupling such that MTs process information in a manner analogous to cellular automata that regulate neuronal activities (trigger axonal spikes, modify synaptic plasticity and hardwire memory by MT-MAP architecture, etc.).

2. Tubulin conformational states and dipoles are governed by quantum-mechanical London forces within tubulin interiors (nonpolar hydrophobic pockets) so that tubulins may exist as quantum superpositions of differing conformational states, thus acting as quantum levers and qubits.41

41 Proteins may be optimally leveraged as qubits in terms of being 1) large enough to exert causal efficacy in the macroscopic world, and 2) small enough/delicately balanced to be regulated by quantum forces. In Hameroff and Penrose [89] the gravitational self-energy E was calculated for tubulin superpositions at the level of 1) entire tubulin protein separation, 2) separation at the level of atomic nuclei, and 3) separation at the level of nucleons, i.e. protons and neutrons. The dominant effect is for separation at the level of atomic nuclei, the Fermi length of 10~6 nm. The eigenstates (differing possible classical positions) of such slight

3. While in superposition, tubulin qubits communicate/compute by entanglement with other tubulin qubits in the same MT, other MTs in the same dendrite, and MTs in other gap-junction-connected dendrites (i. e. within a hyperneuron). Thus quantum computation occurs among MTs throughout macroscopic regions of brain via tunneling through gap junctions or other mechanisms.42

4. Dendritic interiors alternate between two phases determined by polymerization of actin protein: a) In the liquid (solution: sol) phase, actin is depolymerized and MTs communicate/process information classically (tubulin bits) with the external world. During this phase synaptic activities provide inputs via MAPs that orchestrate MT processing. After reduction, sol-phase MT output states regulate axonal firing and synaptic plasticity. b) As actin polymerizes (e. g. triggered by glutamate binding to receptors on dendritic spines), dendritic cytoplasm enters a quasisolid gelatinous (gel) phase, MTs become isolated from environment and enter quantum superposition mode in which tubulins function as quantum bits or qubits (Fig. 6.12). The two phases alternate, e. g., at 40 Hz (Fig. 6.13).

5. Quantum states of tubulin/MTs in gel phase are isolated/protected from environmental-decoherence by biological mechanisms that include encasement by actin gelation, ordered water, Debye screening, coherent pumping and topological quantum error correction (Sect. 6.7.2).

6. During quantum gel phase, MT tubulin qubits represent preconscious (unconscious, subconscious) information as quantum information - superpositions of multiple possibilities, of which dream content is exemplary.

7. Preconscious tubulin superpositions reach threshold for Penrose OR (e. g. after 25 ms) according to E = K/t in which E is the gravitational self-energy of the superpositioned mass (e. g. the number of tubulins in superposition), K is Planck's constant over 2^, and t is the time until OR. Larger superpositions (more intense experience) reach threshold faster. For t = 25ms (i.e. 40Hz) E is roughly 1011 tubulins, requiring a hyperneuron of minimally 104 neurons per conscious event (Hameroff and Penrose [89]). The makeup of the hyperneuron (and content of consciousness) evolves with subsequent events.

8. Each 25 ms OR event chooses 1011 tubulin bit states that proceed by MT automata to govern neurophysiological events, e. g. trigger axonal spikes, specify MAP binding sites/restructure dendritic architecture, regulate synapses and membrane functions. The quantum computation is algo-

shifts will be significant if they are collective for all nuclei in a protein, tipping into basins of attraction upon reduction. Thus superposition of conformations need involve only separation at the level of atomic nuclei. The delicate balance of powerful countervailing forces determining protein conformation lends itself to functioning as a qubit.

42 Centriole entanglement [96], quantum optical photons, Bose-Einstein condensation.

Fig. 6.12. Interior schematic of dendrites in quantum isolation phase. Actin has polymerized into the gel meshwork and MAPs detached, shielding and isolating MTs whose tubulins have evolved into quantum superposition

OR OR OR

Conscious Conscious Conscious

OR OR OR

Conscious Conscious Conscious

Quantum Information

Quantum Information

Classical Information

Classical Information

(Memory)

(Memory)

Fig. 6.13. Conscious events. Top: Microtubule automata enter preconscious quantum superposition phase (gray tubulins) until threshold for OR is met after 25 ms (this would involve superposition of 1011 tubulins in tens of thousands of neurons interconnected by gap junctions). A conscious moment (NOW) occurs, new classical states of tubulins are chosen and a new sequence begins. Middle: Phase diagram of increasing superposition in gel phase that meets threshold after, e. g., 25 ms. A conscious event (NOW) occurs, and the cycle repeats. Bottom: After each OR event, quantum information is sent backward in time to influence previous event. Classical information (memory) goes forward in time rithmic, but at the instant of OR a noncomputable influence (i.e. from Platonic values in fundamental space-time geometry) occurs.

9. Each OR event ties the process to fundamental space-time geometry, enabling a Whiteheadian pan-protopsychist approach to the "hard problem" of subjective experience. A sequence of such events gives rise to our familiar stream of consciousness.

Applications of Orch OR to aspects of consciousness and cognition will be considered in Sect. 6.8.

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