what empirical evidence make you think that 'thought' has a direct mapping to QM, in particular to nuclear spins? 

I don't think It can affect directly the nuclear spins since. The nuclear spins are in a coherent state only in christals near 0k (POLINUCLEAR SUPERRADIANCE). Affecting nuclear spins would not make much difference for our brain, since our brain does not uses the hadrons to process but uses leptons. Not easy  to see how hadron spins can have a physical effect on its relevant electrons.

I really think that entanglement can affect directly the electrons spins and have a paramount role in trasmitting phases through our brain instantly.

@ Remi: I very much like the main idea of your post, namely that classical mechanics are what is probably most relevant to life. But surely a computer has some of the characteristics you attribute to life: its behaviour is, in general, undecidable (if you put a given program in, there is no telling whether it will stop or not). Do computers have ``free will''? Now surely not, but I see no reasons of principle why free-willed agents should be carbon-based, in other words, like us. And, of course, a computer is well-known to work wholly on principles of classical mechanics.

Of course, I do not offer the above as anything certain, or definitive. It is just the way my mind likes to run on that particular subject.

This a young field of research to say a final word  whether there is quantum processing

in our neurons, 

http://phys.org/news/2015-08-neural-qubits-quantum-cognition-based.html

Neurons, nerves and brains are a lot of condensed matter.

How could you preserve an entanglement there ?

Neurosciences are a difficult matter. It is not a sufficient reason to proceed their annexation by the QM physicists, who have no competence at all in neurosciences, nor in endocrinology.

I think that the only role of quantum physics in the brain is that it makes atoms stable and makes chemical bonds to be like they are. This means that in the behavior of brain chemistry we can have genuine quantum randomness but not the entanglement. The entanglement is too fragile and its effects are too tiny to produce neuronal signals or such. Quantum entanglement is so fragile that today it lasts for much less that duration of a single neuronal pulse and is detectable at the level of single photon quanta by most sensitive and bulky setups like  $4 million vacuum chamber filled with squids chilled to 20 mK in order to fight decoherence by ultra-low temperature. The brain, this piece of hot jelly, consisting of ultra-slow neurons, being so insensitive that it can be irradiated by mobile phone EMI for hours without noticing anything, performing any quantum information processing? You must be kidding!

But hey, who knows: we have just started to scratch the surface and, typically, we already think we know everything.

 @Mario Stipčević: http://phys.org/news/2015-11-quantum-entanglement-room-temperature-semiconductor.html

http://phys.org/news/2015-11-quantum-entanglement-room-temperature-semiconductor.html

@Asher Of course, we are doing entanglement in PPKTP today which is heated to 70 deg C but that is not the point. Detectors still have to be chilled well below zero and coincidented within nanoseconds - about million times faster than neurons.  And decoherence is real fast. So what is the use of entanglement if it evaporates million times faster than neurons can react? 

@Mario, thanks but the point is that in such a complex system there may be more that meets the eye. yet, i don't see the use of entanglement even in the abstract, let alone, the lack of evidence for it. people (e.g. John Searle) argue that a 'quantum brain' can explain our free will -- in the sense that it will break the spell of determinism with some uncertainty -- but i don't quite see the difference between prescribed random will and determinism.   

I do not believe that free will is what his thread is about. There are other threads that explicitly deal with that. I think this thread is seeking answer to whether quantum entanglement and other non-classical effects are present and affecting the way our thoughts are processed, and I think they are not present and are not affecting information processing in the brain.

Regarding "free will" I think the problem is that this syntagm is not defined, as well as "consciousness" and "randomness" so threads about them can go on forever,

Dear Prof. Ovgun,

                                According to an intrepretation of Copenhagen conception of Quantum Mechanics I think knowledge is updated by Classical Laws of Probability which is what we know about the quantification of the Uncertainty Principle regarding information processing. Hence quantum entanglement and nuclear spins in our brain, if we are indeed affected by radiation from outside, may affect our functioning of our brain physiologically but not in terms of information processing. Please refer to my paper on Political Uncertainty and String Theory on my RG page, if you will. SKM QC EPS Fellow (Indirect)

@Mario Stipčević forgetting about the question of free will and back to the underlying structure of the brain. It has been Hameroff & Penrose's point for a while that the building block of cognitive brain activity is on the microtubules rather than the neuronal level. Hameroff makes the point that just a single neuron with a billion microtubules each oscillating on a MHz give you 10^16 operations/s per neuron! Note that neuronal level cognitive science puts the entire brain (10^11 neurons) on that scale. Applying to this micro-structure quantum information and logic is practically speaking a wet and worm quantum-biological brain.  

https://www.youtube.com/watch?v=LXFFbxoHp3s

Asher,

I believe both can be true. The whole neuronal model of artificial neural networks is based on the belief that all processing of the brain is done via neurons. Personally I believe that when you pass me the basket ball and I need to decide how much to push muscles to hit the basket, this is done by neurons. Even though if you think how slow neurons are and how many mathematical operations have to be done it almost seems impossible. Namely if one would slow down today's mechanical robots by reducing clock of their FPGAs from about 1 GHz down to a few kHz (that human neurons can match), it probably would take robots days to calculate how to hit the ball correctly. But that is a completely another story.

On another account, the whole brain, the 3 pounds of matter developing physical and chemical processes through time, this blob of matter is actually a piece of quantum computing program that runs in a huge quantum computer commonly known under the name "The Universe". But I do not think that running of all these chemical and physical processes has much to do with the consciouseness, our thoughts or what our hands eventually do as a result of thoughts. For example, when I put my head in 3 Tesla magnetic field for purpose of NMR I felt nothing and my thoughts and limbs certainly did not go berserk. But you can imagine that all spins and orbits were quite different from what they would be without the magnetic field. So at the level of Hameroff & Penrose's quantum information "calculation", things can go in infinitely many different paths without any consequence to the line of thoughts in the brain or anything else that we care about in this thread. Also note that at the time when Penrose and the other guy gave their thesis not only neurologists but much less physicists  had a faintest clue what is going on in the brain. Since then many thesis have been reversed 180 degrees: for example the dogma that neurons cannot be regenerated nor created at an older age. Still today we are only at the beginning of understanding brain. The number of questions rises faster than the number of answers. 

Going back for the moment to the free will, I always thought that claim that quantum information processing would yield the free will because it contains randomness is irritatingly naive. First of all to have randomness you do not need much quantum information processing, only a measurement of it (i.e. projection to an eigenstate). Secondly, if randomness is a crucial ingredient of free will then why a robot equipped with a quantum random number generator (QRNGs can be small and battery operated) cannot have a free will?  Finally. if every time you must bring a decision you MUST throw a dice and do what IT says, would you consider yourself a free-will person or a slave? I think there is much more to free will than randomness. 

the point about MRI is worth citing -- nuclear spins are irrelevant. the relevant energy is mechanical -- the same 8MHz in which the tubules vibrate. Hameroff makes claims based on experiments that ultra-sound affects mood.

in this venue i'll skip the free will problem or for that matter the "hard problem" -- that it is a special niche saved for philosophers --  but i find it hard to dismiss the tubules' 

Asher,

Let me note that showering with warm water does affect mood too and that the average frequency of the thermal field is even much higher than that of ultrasound or microtubules vibration: about 1E12 Hz. However, I'd say that none of this has anything to do with microtubules but with shear transfer of energy to the body, just if someone steps on your foot. Besides, microtubules exist in ANY cell, not only neurons. So you have them in your foot too. 

@Mario, please explain the THz thermal field to a novice.  other than that stay safe, don't let the water wet your microtubules -- remember it's an emergent property of water. also keep your foot work for basketball.