Thought Provoker
Posts: 530
Joined: April 2007
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Hi all,
I am encouraged by most of the responses. SteveStory came to Telic Thoughts looking for something more substantial than the usual YEC "cotton candy" (his term).
I suggest what I offered meets that description.
I am not going to be able to prove this Third Choice hypothesis is a better explaination than the Status Quo. I don't have the training to do so. Dr. Hameroff could offer a better defense of his theory than I. For example, Dr. Hameroff explains what he sees as the role of actin and dendrites in papers (essays?) like this one.
My ability to cut through the medical babble to think in laymans terms is limited. So when Dr. Hameroff says...
Actin is the main component of dendritic spines and also exists throughout the rest of the neuronal interior in various forms depending on actin-binding proteins, calcium etc. When actin polymerizes into a dense meshwork, the cell interior converts from an aqueous solution (sol state) to a quasi-solid, gelatinous (gel) state. In the gel state, actin, MTs and other cytoskeletal structures form a negatively-charged matrix on which polar cell water molecules are bound and ordered (Pollack 2001). Glutamate binding to NMDA and AMPA receptors triggers gel states in actin spines (Fischer et al 2000).
Neuronal MTs self-assemble, and with cooperation of actin enable growth of axons and dendrites. Motor proteins transport materials along MTs to maintain and regulate synapses. The direction and guidance of motor proteins and synaptic components (e.g. from cell body through branching dendrites) depends on conformational states of MT subunits (Krebs et al 2004). Thus MTs are not merely passive tracks but appear to actively guide transport. Among neuronal cytoskeletal components, MTs are the most stable and appear best suited for information processing Wherever cellular organization and intelligence are required, MTs are present and involved.
and Creeky Belly provides a link to a paper (essay?) that says....
Recent work has shown that other actin regulators might modulate the activity of RhoA and thus its effect on spine actin. Ryan et al. showed that the Rho GEF Lcf interacts with the actin-binding protein spinophilin (Ryan et al., 2005). Spinophilin is localized to actin filaments by its actin-binding domain and has crosslinking activities (Grossman et al., 2002; Satoh et al., 1998). The affinity of spinophilin for F-actin is regulated by phosphorylation of the actin-binding domain, which can be mediated by PKA and CaMKII (Grossman et al., 2004; Hsieh-Wilson et al., 2003). In neurons, Ca2+-dependent phosphorylation by CaMKII reduces the affinity of spinophilin for actin and targets the protein to synaptic membrane fractions (Grossman et al., 2004). Expression studies in hippocampal neurons showed that Lcf localizes to the cell body and the dendritic shaft, where it associates with microtubules.
It is going to take a lot of effort on my part to understand the fundamental differences between the two.
I have explained my reasoning for why, from a top-level view, the Third Choice sounds feasible. It has backing of true scientists that I feel are ethically and honestly presenting ideas.
Sir Rodger Penrose agrees that he may very well be wrong about biological sources for consciousness. He is much more convinced of his physics and mathematics. His quantum interpretation, like his model for Black Holes, is too complete and consistent with reality to be easily dismissed. His mathematical proof against Strong AI is solid (after a minor adjustment that was compelled by peer review).
The logical implication of Penrose's understanding is that awareness/consciousness is directly tied to quantum effects. Call it a prediction. Has this prediction been verified yet? No, but Dr. Hameroff offers his opinion on reasons for optimism.
I find all this interesting and it provides fuel for debates in blogs and forums. I am not suggesting this should be taught in public schools. At least not yet.
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