ANNOTATION:
Has it been proven that Quantum mechanics goes on in the brain.

I think that before one can discount determinism one would have to do more than simply show that there is a relatively new theory called Quantum Mechanics out there that doesn't follow the old rules of Newtonian cause and effect. One would have to prove two things, I think. First, one would have to prove that these quantum mechanic states are indeed taking place and interacting in the parts of the brain where and when the process of 'deciding' takes place. If one can prove this then one would next, I think, have to prove that the consciousness of the brain, the core self or soul, if you like, is somehow capable of controlling the quantum mechanic states. So, if QM exists but doesn't play a role in the decision making process, or if QM does play a role in the decision making process but the core self cannot determine those QM states, then we are still left without free-will. If you have any good scientific studies addressing, in any way, these two necessary proofs, I'd be obliged if you could give some reference so I could go study them.

p.s. I'm a pretty firm believer in determinism and from what I've learned so far, QM doesn't threaten to undermine it. I speculate that QM, instead, will offer answers to more difficult problems, such as how the brain produces consciousness.

Sincerely

REPLY:

REPLY: Free Will, QM and the Brain

It was good to see Mark's annotation demanding more than the
simple existence of quantum states to verify that free will
exists for humans. One way I like to think of Mark's first
 requirement, that quantum states occur in the brain and
influence consciousness is this: in the quest for a quantum
computer, are we overlooking the fact that we're all carrying one
around inside our heads?
To begin to answer Mark's question, I have no proofs, only a few
facts and much speculation. The first fact is obvious, quantum 
events are taking place in the brain. The brain is no less and
no more a conglomeration of quantum events than is the table in
front of me. And the question about such objects, for physicists
and philosophers alike is, at what threshold do relatively low
predictability quantum events organise themselves into high
predictability classical mechanical events?
I think in biological systems, we have a relatively good
framework for answering this. Clearly cell-scale events are 
classical mechanical events. We can directly observe them
unfolding with great predictability. Just as clearly, small 
biological molecules such as the major neurotransmitters are
governed by quantum mechanics. They interact mostly by forming a
few hydrogen bonds, a relatively weak form of bonding quite
sensitive to the quantum states of the molecules' constituent
particles. What's even more interesting is that in biology, these
two scales are not very far apart. Between the scale of a cell 
organelle such as a mitochondrion, and that of a small molecule
such as acetylcholine, there is only one important level of
activity, that of the macromolecule.
The most fascinating macromolecules of all are globular proteins. 
Among all the molecules of chemistry and biochemistry, these are
what the human brain is among all the organs of all the animals.
The models that we have for enzyme action, for example, make 
them seem almost intelligent: "choosing" their target molecules
with high specificity, binding them and manipulating their shapes
in "clever" ways, then releasing them, ready to do a new job. We 
even draw pictures of them with open "sub-molecular" jaws, 
waiting for their smaller prey.
Yet the picture we draw of an enzyme is completely different in
derivation from the one we draw of a mitochondrion. The latter 
picture is derived from real electron micrographs of individual
mitochondria, in considerable detail. This is the observational 
method of classical mechanics: Galileo did not have to drop 
thousands of balls to get an idea of how a falling ball behaves,
direct observation of a few sufficed. In contrast, the picture we
have of an enzyme may look pretty, but is actually wholly
statistical: this is how we think they look, given the
diffraction pattern of thousands of them dried out, cystallized
and exposed to x-rays, or assayed for the kinetics of their 
reactions, or laboriously predicted by matching observations
about their bond strengths with the Schrodinger equation. This is
the observational method of quantum mechanics.
So globular proteins have one foot in the world of quanta, we 
understand them by quantum mechanical means. However, they
also seem to have a foot in the classical world, in this way: 
although we require quantum methods to learn about them, what we
learn shows rather elegant, if rigid, classical behaviour. Unlike 
molecules the size of neurotransmitters, about any one of which
you can predict nothing useful, requiring thousands to millions
to achieve consistency, a few dozen molecules of an enzyme such 
as DNA transcriptase, given enough ATP, will carry on with a
predictability and fidelity sufficient to ensure near immortality
for the genes of their cell.  
I hope this discussion has sufficiently demonstrated that in
biology at least, the threshold from quantum to classical lies 
with the macromolecules, most spectacularly with the globular 
proteins. The next question then becomes, how does this threshold
relate to human brain function? Well, interestingly enough,
there is evidence that the smallest information-coordinating unit
of the human brain is the globular protein, or small groups of 
globular proteins. It has been pointed out that neurons fire in a
binary fashion: they each have only one output pathway, the axon,
and it either fires an action potential, or it doesn't.
This has obvious appeal for computer analogies. However, it's not
the mere existence of an action potential that's relevant to the
next neuron in the chain, it is the firing frequency of the axon,
which is a non-quantum, non-binary, graded response. However, if
we look at what causes the action potential and its frequency, it 
is clear that the neuron is, in itself, already a tiny computer.
Thousands to millions of inhibitory and excitatory post-synaptic
potentials from its thousands of dendrites subtract or summate to 
cause, or not cause, an action potential.
And how are these small post-synaptic potentials generated? By 
neurotransmitter receptors and receptor-linked proteins, globular
proteins very similar in their functions to enzymes. And what 
causes these receptors to fire these potentials? Why, the number 
of neurotransmitter molecules they receive and bind. So it's
possible to view each neurotransmitter molecule as the
fundamental unit of information, and each receptor protein as the
simplest locus of computation. Note that for neither is there a
definite binary element, rather, neurotransmitters deliver a 
graded effect, although the threshold response of the receptor
may introduce a binary effect.
Well, that just about plays me out for now. I hope I've been 
convincing that the scale of human brain computation allows at
least the possibility of quantum effects. In my next installment,
I hope to explore whether this possibility is probable enough to
allow for free will.
John Hostetler