The issue of the brain and its relation to consciousness is one that interests and intrigues many physicists. The standard take by many is that quantum mechanics isn't involved at all. For example, physicist Mark Alford, writing in the Skeptical Inquirer ( May-June, 2011, p. 8 ) observed:
"It seems improbable that these very delicate processes are the crucial feature in the functioning of the human brain which is not a suitagle environment for quantum subtlety".
But is this so? For example, we know that the scale of the synaptic cleft is on the order of 200-300 nm and hence subject to the Heisenberg Uncertainty Principle. This is precisely a quantum scale so it makes sense that the Heisenberg Principle would apply at this level, and hence quantum mechanics also.
Using this logic, I introduced a quantum model for consciousness in my book, 'The Atheist's Handbook to Modern Materialism', (Chapter 6), and developed it by appeal to how a quantum computer would operate via "quantum gates" predicated on the Pauli spin operators. This entailed conversion of standard logic gates (NOR, OR, NOT, etc.) in the classical format - applied to ordinary computers- to counterparts in the quantum format.
For example, the NOT gate can be represented by what is called a unitary matrix, or Pauli spin matrix-operator σ_x = (0,1¦1,0) where the left pair is a matrix 'top' and each right pair a matrix 'bottom' - since they are usually written in a rectangular array form.
Similarly, the other Pauli gates would be defined by: σ_y = (0,-i¦i, 0)and σ_z = (1, 0¦0, -1), where i denotes the square root of (-1). Incorporation of such Pauli (quantum) gates meets a primary application requirement for feed forward networks, in describing synapse function. (See e.g. Yaneer Bar-Yam, 'Dynamics of Complex Systems', Addison-Wesley, pp. 298-99.)
The advantage is consciousness is elevated out of the strict machine-like model of an ordinary computer to one that can explain more features of the human experience.
In my book I used this basis to challenge Daniel Dennett's claim (in Consciousness Explained) that quantum mechanics isn't needed and Newtonian classical mechanics suffices to account for any particulate interactions. But as I pointed out, it was physicist Henry Stapp who first pointedly noted that uncertainty principle limitations applied to calcium ion capture near synapses showed they (calcium ions) must be represented by a probability function. (Stapp, Henry, P.: 1993, Mind, Matter and Quantum Mechanics, Springer-Verlag, p. 42.)
I also used it to challenge Michio Kaku's simple deterministic model of mind, e.g.
http://brane-space.blogspot.com/2014/03/michio-kakus-model-of-mijnd-is-too.html
Now, new support for this view appears to have arrived with the book, 'Life On the Edge', by Johnjoe McFadden and Jim Al-Kahlili - a quantum physicists - reviewed by John Gribbin in the WSJ ('Physics for Bird Brains', Aug 1-2, p. C5). Gribbin begins by noting "the entangled strands of DNA....are held together by a quantum phenomenon know as hydrogen bonding. The way these strands untwist and build new double helixes is at heart a quantum phenomenon"
So why not brain operation as well? This is one thread in the book, using concepts of "quantum weirdness" and entanglement, see e.g.
http://brane-space.blogspot.com/2014/11/the-epr-paradox-and-quantum-nonlocality.html
that ultimately leads to a novel account of brain operation. As Gribbin puts it (ibid.):
"The authors have saved the best - if most speculative idea- for last: that quantum procedures help explain consciousness and the mechanics of thought, as surely as they do photosynthesis... It is an old question going back to philosophers such as Descartes: How does mind make matter move?"
He elaborates a bit more without giving away too many details:
"The new answer presented draws from the physics behind those quantum computers. Where an ordinary computer can be thought of as operating through a series of switches that can be set at 1 or 0, the power of a quantum computer depends on the ability of quantum entities to be in two state at once, known as a superposition"
Which was exactly the point I raised in my own book. So rather than limit storage to bits (1 or 0), one can work with qubits (truncated for quantum bits) where the superposition of a combined data element (1 + 0) applies:
U = U(1) + U(0)
And the storage capacity dramatically expands as a result.
In general, for any given n-bit combination – with n a whole number, a qubit register can accommodate 2 to the nth power total combinations at one time. Thus, 16 combinations could be held in memory for 4-bits, 32 for 5-bits, and so on. This change marks an exponential (two to the 'n' or 2^n) increase over any classical counterpart. Since, human brains typically can hold the equivalent in memory of whole libraries, it seems that qubit processing is at least worth consideration.
As Gribbin concedes, and the authors as well, all this is still in the realm of conjecture. No one as yet has inserted experimental probes into brains to precisely detect quantum wavepacket collapse, energy exchanges or energy increases owing to repeated superpositions and nonlocal actions.
However, from Bell's theorem there is powerful theoretical support, as the most recent book makes use of. Indeed, Bell himself may have suggested a clue on how to proceed experimentally (Foundations of Physics, (12,) .989 ):
Although Y is a real field it does not show up immediately in the results of a ‘single measurement’, but only in the statistics of many such results. It is the de Broglie –Bohm variable X that shows up immediately each time.
In other words, the best approach may be a large number of experiments from which multiple measurements are obtained, perhaps similar to those conducted by Dr. Robert G. Jahn (using random number generators), as published in The Journal of Scientific Exploration. (Vol. 1, No. 1).
At the very least this latest work provides more philosophical and explanatory support for the integration of quantum mechanics into brain operation.
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