It's almost ten years since I promised to comment here, on Stuart Hameroff and Roger Penrose's theory of consciousness. But first let me state some of my general views on quantum theories of mind:
1) Subjectively we know that consciousness is a complex unity. For the details, see phenomenological studies of qualia, intentionality, etc.
2) Given what physics offers us, if we are going to identify that complex unity with something from the physical world, it's apriori likely that entanglement is involved.
3) The microtubule is a good candidate for the basic locus of biological entanglement, since the entanglement can be wrapped around the cylinder and thereby stabilized against the thermal fluctuations of living matter.
4) Ultimately one wants a detailed correspondence between the mereology (the structure and composition) of consciousness, and the mereology of the physical quantum mind. (One would want this for a physical theory of mind that is not quantum, too.)
So, what does their theory of Orchestrated Objective Reduction say?
a) The neural correlate of consciousness is a quantum state "in layer 5 pyramidal neuron soma and dendrite microtubules. So anywhere in cortex, moving around depending on the task and mode".
b) The individual tubulins (from which these microtubules are made) get into objective quantum superpositions thanks to molecular dynamics, and then these superpositions are collapsed by an unknown supra-quantum dynamics.
c) Inter-neuronal quantum dynamics is mediated by dendritic-dendritic gap junctions, which allow direct interactions between the cytoplasm of neighboring cells.
d) Everything to do with consciousness involves the structure and dynamics of this mobile, multi-neuronal, microtubular quantum state. All the other information processing of the brain is unconscious.
To be continued...
