4. Double Slits, Nerve Terminals, and the Necessity to Use 
Quantum Brain Dynamics.

Neuroscientists and philosophers probing the relationship of 
consciousness to brain process appear to believe, almost 
unanimously, that classical physics provides the relevant description 
of the conscious brain. That belief would have been reasonable 
during the nineteenth century, but now, in the twenty-first, it is 
rationally untenable. The general dynamical reason why quantum 
theory must be used when the effects of consciousness are involved 
was described in the preceding chapter. But the further question is a 
quantitative one: How important are the quantum wave-like (i.e., 
cloudlike) properties of, say, ions in brain dynamics? That they are 
very important is made particularly evident by an examination of the 
dynamics of nerve terminals. 

Nerve terminals lie at the junctions between two nerves, and mediate 
the connection between them. The way they work is this. Each 
“firing” of a nerve sends an electrical signal along that fiber.  When 
this signal reaches the nerve terminal it opens up tiny holes in the 
terminal membrane, through which calcium ions flow into the interior 
of the terminal. Within the terminal are “vesicles”, which are small 
sacks containing chemicals called neurotransmitters. The calcium 
ions migrate from their entry holes to special sites, where they trigger 
the release of the contents of a vesicle into a gap between the 
terminal and a neighboring nerve. The released chemicals influence 
the tendency of the neighboring nerve to fire. Thus the nerve 
terminals, as connecting links between nerves, are basic elements in 
brain dynamics.

The holes through which the calcium ions enter the nerve terminal 
are called “ion channels.” At their narrowest points they are not much 
larger than the calcium ions themselves. This extreme smallness of 
the opening in the ion channels has profound quantum mechanical 
import. The consequence is essentially the same as the 
consequence of the narrowness of the slits in the famous double-slit 
experiments, which prove the wave nature of photons, electrons, and 
ions.     

In all these cases the smallness of the hole or slit restricts the lateral 
dimension of the beam. Consequently, the lateral velocity is forced 
by the quantum uncertainty principle to become large. This causes 
the wave packet associated with the particle to balloon out over an 
increasing area as it moves from the tiny hole or slit to the target 
where it will be absorbed on some small site.

This spreading of the ion wave packet means that the ion may or 
may not be absorbed on the triggering site.   Accordingly, the vesicle 
may or may not release its contents. Consequently, the quantum 
state of the vesicle becomes a quantum superposition consisting of 
a state where the neurotransmitter is released and a state where the 
neurotransmitter is not released. This quantum splitting occurs at 
every one of the trillions of nerve terminals.

What is the effect of this necessary incursion of the wave nature of 
matter into the evolving state of the brain? 

A principal function of the brain is to receive clues from the 
environment, form an appropriate plan of action, and direct the 
body/brain action specified by the selected plan of action. The exact 
details of the plan will, for a classical model, obviously depend upon 
the exact values of many noisy and uncontrolled variables. In cases 
close to a bifurcation point of the dynamics the effects of noise 
might even tip the balance between two very different responses to 
the given clues: e.g., tip the balance between the ‘fight’ or ‘flight’ 
response to some shadowy form. 

The effect of the independent superpositions of the “release” or 
“don’t release” options at each of the trillions of nerve terminals will 
be to cause the quantum mechanical state of the brain to become a 
collection of different states representing different alternative 
possible plans of action. As long as the brain dynamics is controlled 
wholly by ProcessII---which is the quantum generalization of the 
Newtonian laws of motion in classical physics---all of the various 
alternative possible plans of action exist in parallel, with no one plan 
of action singled out as the one that will actually occur. Some other 
process, beyond the local deterministic Process II, is required to 
select some particular real course of events from the smeared out 
mass of possibilities generated by all of the alternative possible 
combinations of vesicle releases at all of the trillions of nerve 
terminals.

But what is this other process that selects distinct alternatives with 
well defined probabilities from the amorphous conglomeration of 
overlapping possibilities. According to both the Copenhagen and 
von Neumann formulations of quantum theory it is Process I.

Curiously, almost all physicists who attempt to improve upon these 
orthodox formulations of quantum theory  see the problem with these 
mainline views as this intrusion of the observer into physics: their aim 
is to try to rid quantum theory of “the observer”, who by virtue of his 
subjective nature, must, in their opinion, be excluded from science. 
Thus most neuroscientists, philosophers, and physicists stand firmly 
united in the contemporary determined attempt to rid science of 
ourselves, considered as anything beyond the mechanical notion of 
human beings inherited from pre-twentieth century science. This 
stance is maintained in direct opposition to what would seem to be 
the most profound advance in physics in three hundred years, 
namely the overcoming of the most glaring failure of classical 
physics, its inability to accommodate us, its creators. The most 
remarkable and salient feature of quantum theory is that the 
mathematics has a dynamical gap that, by virtue of its intrinsic form, 
provides a perfect place for Homo sapiens as we know and 
experience ourselves. That was the conclusion reluctantly 
recognized by the founders of quantum theory already in 1926, and 
clarified by von Neumann in 1932. In view of the profound 
philosophical difficulties attendant upon the classical mechanical 
conception of man it is odd that any thinking person would want to 
revert to it.