Tuesday, June 7, 2011

Neurology and the Soul

I've just found time to read John Wilkin's Is the soul something we should be agnostic about?, as well as two posts he links to: Sean M. Carroll's Physics and the Immortality of the Soul and PZ Myers' Ain't no heaven, ain't no afterlife of any kind, either, say the physicists.

Are you folks kidding me? Or has physics actually discovered and verified an underlying source of determinism while my back was turned? Or is everybody missing at least one part of the big picture? (Or am I imagining things?)

The underlying assumption in all these arguments is that there's no way for something going on in "spirit space" to interact with the real world. Now, I don't claim to be the physicist Sean M. Carroll is, in fact my understanding is amateur and older than decoherence. But my understanding is that, in practical terms, quantum indeterminacy still reigns, at least with regard to even theoretically predicting the outcome of local wave function collapse (or, if you wish, "decoherence").

Consider the situation where an action potential arrives at a synapse, and releases a certain amount of neurotransmitter. The number of molecules of neurotransmitter vary within a small range due "indeterminacy", and the number of receptors for that neurotransmitter that are actually active will also vary, depending on many factors within the cell, many of them also slightly "indeterminate". Thus the actual size and shape of the current resulting from that action potential can vary within small limits. (In fact, even with a fixed number of molecules of neurotransmitter and receptors, there will be some variation in current due to indeterminacy of position of each neurotransmitter molecule while diffusing across the synaptic gap.)

Now, let's suppose that that one action potential is just on the border of causing the receiving neuron to fire an action potential. That is, given the current (heh) condition of the nearby dendritic arbor, the amount of current necessary to cause an action potential to fire is right in the middle of the potential variation (in current) due to indeterminacy.

Does the neuron actually fire? Or does it end up in a state of superposed states of firing and not firing? Well, I think we can state that it fires, that is that decoherence has taken place. Do we actually know the source of all the information involved in the decoherence?

We don't, of course. People who state that decoherence has proven that everything happening on the quantum state is completely deterministic are simply projecting their own prejudice (i.e. religious convictions) on what is still a highly controversial field. There's plenty of room in those little wave function collapses for huge amounts of information to flow into our universe.

We certainly don't know how many of the neurons in our brains actually balance on the head of this pin. For that matter, the calculations that go on in the dendrites to integrate the information from the current flows in the synapses also depend on distributed molecules of receptors, most of which open and close "randomly" depending on quantum processes that contain "indeterminacy".

So, is it possible for:
some sort of blob of spirit energy that takes up residence near our brain, and drives around our body like a soccer mom driving an SUV?

as Sean M. Carroll mocks and PZ Myers quotes? Well, conceivably, if we assume these "spirit" people are using the word "energy" metaphorically. (Which they probably are since they don't understand physics or thermodynamics well enough to use it in a technical sense.)

Of course the blobs of "spirit energy", actually some sort of informational phenomenon, would have to have some way of predicting the outcomes of all their interventions in these decoherences. Perhaps time and information work differently in "spirit space". Perhaps they can "see" the potential outcomes of different combinations of interventions directly, rather than having to compute it with incredibly powerful modeling. In the same way, perhaps, that a man riding a balloon can see the road ahead without having to rely on asking passing strangers about it.

Of course, this is all very interesting, and would make a great "magic system" for a fantasy novel, but is there any evidence, no matter how tenuous, that such a thing might be so?

Actually yes. Compared to other anthropoid species, humans have a third or so higher ratio of glial cells to nerve cells in at least on area of the dorsolateral prefrontal cortex (area 9L):
Based on the nonhuman species mean LS regression, humans displayed a 46% greater density of glial cells per neuron than expected.


From this prediction, glial density in humans fell within the 95% PIs (observed log glial density = 5.19; predicted = 5.02; upper PI = 5.40, lower PI = 4.63) and represented 32% more glia than expected.[1]
Perhaps the human brain has evolved, over the last few million years, to be "ridden" by a "blob of spirit energy", and supporting the receipt of information from the blob is what requires the extra glial activity.

Of course, the actual increase isn't all that great, and:
The human frontal cortex displays a higher ratio of glia to neurons than in other anthropoid primates. However, this relative increase in glia conforms to allometric scaling expectations, when taking into consideration the dramatic enlargement of the human brain. We suggest that relatively greater numbers of glia in the human neocortex relate to the energetic costs of maintaining larger dendritic arbors and long-range projecting axons in the context of a large brain.[1]
So this "evidence" is highly tenuous. But that's very different from saying it would require a new formulation of natural law.

So when PZ Myers says:
The biologists' perspective, which is a little less fundamental, is simply that there is no identifiable 'receiver' localized in the brain (no, not even the pineal gland, as Descartes believed), distributed physiological activity is associated with thought, and injury, disease, and pharmacology can all profoundly influence the mind. Furthermore, the way the brain works involves trans-membrane ion fluxes and synaptic activity — it's all electrochemistry and biochemistry. In addition to that new physics, we'd need a new chemistry to explain how spirit interacts with neurotransmitters or gene expression or protein phosphorylation.
Well, we don't need "new" physics (although we would need to add some stuff to the one we have) and we don't need new chemistry. The receiver is distributed, just like the physiological activity.

Despite what atheists would like to believe, there are still big holes in our scientific understanding of the world; big enough to drive the biggest spirit.

For the moment, I'd recommend agnosticism.


1. Chet C. Sherwood, Cheryl D. Stimpson, Mary Ann Raghanti, Derek E. Wildman, Monica Uddin, Lawrence I. Grossman, Morris Goodman, John C. Redmond, Christopher J. Bonar, Joseph M. Erwin, and Patrick R. Hof Evolution of increased glia–neuron ratios in the human frontal cortex PNAS September 12, 2006 vol. 103 no. 37 13606-13611 doi: 10.1073/pnas.0605843103


  1. There's a difference between ignorance and indeterminacy. Sean's point is that we have the later but not enough of the former to support a spirit world.

  2. But, IMO Sean's projecting his own (religious) preference for determinacy on physics.

    If we have true "indeterminacy", the information for the decoherence is "coming out of nowhere", which would make it truly random. But there's no way to distinguish information that's truly random from information that's ordered according to a system orthogonal to your own observations. Thus, most random number generators on computers just go to some pseudo-random area of storage and pull out some 1's and 0's. This information isn't really random, but as long as it comes from another task than the one requiring random numbers, it's just as good.

    The same thing applies to "indeterminacy". If the information entering the system is actually random, you'll never be able to distinguish it from information entering according to a system ("for a purpose", to speak teleologically) orthogonal to your own observational purposes.

    Only by demonstrating that all the information entering the system during decoherence is actually determined by the prior state of the system can you exclude "leaks" or even floods from an outside source.

    For purposes of excluding agnosticism, we not only need a system that does that, we also need complete agreement among physicists that it does, that it's correct, and that (in this instance) the source of this information (presumably the random activity of water molecules) isn't entangled with any other systems that might act as a source of information.

    AKAIK that agreement is completely absent.

  3. Excellent essay.
    I am always puzzled by those who leap from evolution to outright atheism.
    I enjoyed Carroll's book explaining gene packages and tools, but I found it ironic that he was declaring the end of God by way of an explanation that implies a designer and tool maker.

  4. AK,

    1) What proportion of action potentials are really on that knife's edge of firing that makes quantum effects relevant? QM has extremely little effect at the scale of neurotransmitter molecules. For example, an individual GABA molecule has a mass of ~10^-22 g, a length of ~10^-9 m, and an average gas velocity of ~100 m/s, thus the quantum vibration of the molecule is conservatively one trillionth of its length.

    Congratulations, you have hypothesized a pathway for spirit processors to have a miniscule amount of control, even with perfect operation.

    2) Even if it was unexplained, neuroglia-to-neuron ratio would not be highly tenuous evidence that spirit processors are controlling our neural networks. At best it is a hypothetical pathway.

    1. Actually, quantum uncertainty can extend to much larger distances. For instance, in classic interference experiments, photons, or even electrons, with sizes measured in fractions of a micron/angstrom respectively, can produce interference effects over meters.

      I'm assuming that indeterminacy with respect to location of neurotransmitters and receptors can be many orders of magnitude larger than the size of the particles involved.

    2. Quantum uncertainty can indeed play a large role at the electron scale, but it plays a much smaller role at the molecular scale.

      Neurotransmitters have many orders of magnitude greater momentum and energy than electrons and photons, and thus neurotransmitters have many orders of magnitude less quantum uncertainty in space and time.

  5. Frontiers of Faith and Science,

    I would assume that the leap from evolution to atheism has less to do with direct logic and more to do with evolution demonstrating in one fell swoop both the awesome creative power of mindless processes and the total absurdity of traditional religious explanations regarding the history of life on earth.