Thank you for your post!Can you point to a single neural structure discussed by Penrose that isn't present in, say a flatworm? Are the neurons of "simpler" organisms fundamentally different from ours?
Evidently, the non-computable effect is what is missing according to Penrose. The excerpt is repeated below, emphasis mine:
14.5 With regard to the theoretical possibility of quantum coherence within microtubules, the model of Jibu et al (1994) seems well-founded, in which super-radiance effects are anticipated within microtubules (analogous to the activity of a laser), where the electromagnetic field interacts with ordered water. For this process to occur, it would be necessary for the water within the tubes actually to adopt this ordered structure, and to be appropriately free of the wrong kind of impurities, such as chloride ions. (Apparently, sodium, calcium, magnesium, and potassium ions, in low enough concentrations should not disturb the ordering.) It should be mentioned, however, that the type of coherent activity that is anticipated in the model of Jibu et al may not be sufficient for my purposes. Though it is a necessarily quantum effect, it is not, as it stands, a quantum-coherent effect of the type that my arguments require. Genuine quantum coherence seems to be necessary in order that the quantum/classical borderline can be probed, where the (non-computable) effect of the missing OR theory can significantly make its mark. (This comment has relevance to Klein's query at the end of his Section 1. Classical coherence in the brain may well occur, but it does not provide an opening for non-computational activity, which I argue is a characteristic feature of consciousness.) The Jibu et al mechanism may be part (though not all) of what is needed.