**5. The Eccles-Beck Approach.**

Sir John Eccles suggested in 1990, in the Proceedings of the Royal
Society (Eccles 1990), that quantum theory plays a key role in the
workings of the conscious brain. Based in part on his discussions with
Henry Margenau (See Margenau 1984), Eccles noted that the statistical
element in quantum theory allows an escape from the rigid determinism of
classical physics that has plagued philosophy since the time of Isaac
Newton. In his later book "How the self controls its Brain" Eccles
(1994) notes that , "There is of course an entrenched materialist
orthodoxy, both philosophic and scientific, that rises to defend its
dogmas with a self-righteousness scarcely equaled in the ancient days of
religious dogmatism." He says at the outset that, "Following Popper
(1968) I can say:

I wish to confess, however, at the very beginning, that I am a realist:
I suggest somewhat like a naïve realist that there is a physical world
and a world of states of consciousness, and that these two interact."

Eccles gives "two most weighty reasons" for rejecting the
classical-physics-based concept of materialism. (Eccles 1994, p,9)
First, classical physics does not entail the existence or emergence of
the defining characteristic of consciousness, namely "feelings," and
hence entails no theory of consciousness. Second, because the nature of
the mapping between brain states and states of consciousness never
enters into the behavior of an organism, there is no evolutionary reason
for consciousness to be closely connected to behavior, which it clearly
is.

Eccles' approach to the mind-brain problem has three main points. The
first is that consciousness is composed of elemental mental units called
psychons, and that each psychon is associated with the activation of a
corresponding macroscopic physical structure in the cerebral cortex that
Eccles calls a *dendron*. It is anatomically defined, and is connected
to the rest of the brain via a large number of synapses.

The second point is the claim that quantum theory enters brain dynamics
in connection with exocytosis, which is the release of the contents of a
"vesicle" -- filled with neurotransmitter -- from a nerve terminal into
a synaptic cleft.

The third point is a model developed by the physicist Friedrich Beck
that describes the quantum mechanical details of the process of
exocytosis.

The first claim, that psychological processes have elemental units
associated with dendrons, places Eccles' theory somewhat apart from
those who have suggested that *the electromagnetic field* in the brain
might server as the carrier of the physical correlate of consciousness.
(Taylor 2002, McFadden 2002, Pockett 2002, Pockett 2000, Stapp 1987,
Stapp 1985) Evidence for the electromagnetic hypothesis has been
presented particularly by McFadden. However, the very close causal
connection between the activation of a dendron and the activation of an
electromagnetic field in the neighborhood of that dendron makes these
two proposals difficult to distinguish, empirically.

More germane to our topic is the second component of Eccles' proposal,
which is that quantum effects enter importantly into brain dynamics in
connection with cerebral exocytosis. This is a very plausible, and
indeed inescapable, conclusion. Exocytosis is instigated by an action
potential pulse that triggers an influx of calcium ions through ion
channels into a nerve terminal. These calcium ions migrate from the
ion-channel exits to sites on or near the vesicles, where they trigger
the release of the contents of the vesicle into the synaptic cleft. The
diameter of the ion channel through which the calcium ion enters the
nerve terminal is very small, less than a nanometer, and this creates,
in accordance with the Heisenberg uncertainty principle, a
correspondingly large uncertainly in the direction of the motion of the
ion. That means that the quantum wave packet that describes the location
of the ion spreads, during its travel from ion channel to trigger site,
to a size much larger than the trigger site (Stapp 1993/2003.) That
means that the issue of whether or not the calcium ion (in combination
with other calcium ions) produces an exocytosis is a quantum question
that is basically similar to the question of whether or not a quantum
particle will pass through one or the other slit of a double-slit
experiment. According to quantum theory the answer is 'both': until the
brain process reaches the level of organization corresponding to the
occurrence of a Process I action one must retain *all* of the
possibilities generated by the Schroedinger equation, Process **2**. In
particular, one must retain both the possibility that the ion activates
the trigger, and the exocytosis occurs, and also the possibility that
the ion misses the trigger site, and the exocytosis does not occur.

For cortical nerve terminals the observed fraction of action potential
pulses that result in exocytosis is considerably less than 100%. This
can be modeled classically. (Fogelson 1985.) But the large Heisenberg
uncertainty in the locations of the triggering calcium ions, entails
that the classical uncertainties will carry over to similar quantum
uncertainties, and the two possibilities at each synapse, 'exocytosis'
and 'no exocytosis', will, prior to the occurrence of the Process **1**
or Process **3** actions, *both be present* in the quantum state S(t).
If N such synaptic events occur in the brain during some interval of
time in which no Process **1** or **3** events occur, then the state
S(t) of the brain will evolve during that interval into a form that
contains (at least) 2^N^ contributions, one for each alternative
possible combinations of the 'exocytosis' and 'no exocytosis' options at
each of the N synapse events.

There is a lot of parallel processing and redundancy in brain dynamics
and many of these possible contributions may correspond to exactly the
same possible experience 'e'. But in real life situations where there
could be several different reasonable actions one cannot expect that
every one of the 2^N^ alternative possible brain states will be a neural
correlate of *exactly* the same possible 'e'. If the agent is conscious
then the von Neumann Processes **1** and **3** must enter and determine
which of the various alternative possible experiences 'e' actually
occurs.

The analysis just given assumes, in accordance with the model of
Fogelson and Zucker (Fogelson 1985), that the condition that triggers
exocytosis is the presence of a specified number of calcium ions on a
trigger site. Beck (2003) considers another possibility. He says that
the "low exocytosis probability per excitatory impulse ...means that
there is an activation barrier against opening an ion channel in the PVG
(presynaptic vesicular grid.) He proposes that "An incoming nerve pulse
excites some electronic configuration to a metastable level, separated
energetically by a potential barrier V(q) from the state that leads to
the unidirectional process of exocytosis." Then the state in which the
exocytosis does occur can be considered to be connected by a *quantum
tunneling process* to the state where it has not occurred*.*

*Beck's tunneling mechanism would achieve the same result as the*
mechanism, described above, which is based simply on the spreading of
the wave packet due to Heisenberg's uncertainty principle. Both
mechanisms lead to the result that the brain state S(t) will contain
2^N^ states, defined by 'exocytosis' or 'no exocytosis' options
independently at each of the N synapses. So the Eccles-Beck model does
not lead to any essential difference from the vN/S model as regards this
key point.

However, the Eccles-Beck proposal does differ importantly from the vN/S
proposal in regard to their third point. The vN/S theory attributes the
efficacy of will to the assumed power of mental effort to increase the
rate of Process **1** actions, whereas the Eccles-Beck proposal
attributes the efficacy of will to the assumed power of mental effort to
modify *the probabilities associated with the Process **3** action*, the
collapse of the quantum state.

The vN/S proposal stays rigorously within the framework of relativistic
quantum field theory, and produces no causal anomalies, such as the
possibility of sending messages backward in time, whereas the
Eccles-Beck proposal, by disturbing the basic quantum probability rules,
would in principle enable such anomalies to occur.

It is often correctly emphasized, in connection with quantum approaches
to brain dynamics, that "the environment" will be affected differently
by interactions with the brain states in which an exocytosis has or has
not occurred, and that this difference will destroy, almost immediately,
all (practically achievable) interference effects between these
macroscopically distinct states.

This *environmental decoherence effect* is automatically included in the
formulas used here, which refer explicitly to the brain state S(t),
which is the brain-state statistical operator obtained by averaging
(tracing) over all non-brain variables.

It is then sometimes concluded, incorrectly, that one can immediately
replace the brain state S(t) by just *one* of these 2^N^ components.
That conclusion might follow only if one were to ignore Process **1**,
which is part of the brain process that defines which of our alternative
possible thoughts actually occurs next. Since Process **1** is part of
the process that determines which thought occurs next, it should depend
upon the state S(t) of the brain *before* the thought occurs. The
operator P(t), defined in the section 4, singles out the experience 'e'
such that P(e) has maximal statistical weight *before the event*. It is
defined by using the S(t) just prior to the collapse event, even though
that instant will usually be after the environmental decoherence effect
has occurred.

The model of the brain used above, with its 2^N^ well defined distinct
components is, of course, highly idealized. A more realistic model would
exhibit the general smearing out of all properties that follows from the
quantum smearing out of the positions and velocities of all the
particles. Thus the state S(t) prior to the collapse cannot
realistically be expected ever to be rigorously divided, solely by
Process **2** action, including interaction with the environment, into
strictly orthogonal non-interfering components corresponding to distinct
experiences. It is Process **1** that makes this crucial separation, not
Process **2**. The recognition of the need to bring in a separate
process, Process **1**, to achieve this end was one of von Neumann's key
achievements, and any attempt to evade the need to include Process **1**
faces daunting challenges.

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

Beck, F. & Eccles, J. (2003). Quantum Processes in the Brain: A
scientific basis of consciousness. In N. Osaka (Ed.), *Neural Basis of
Consciousness*. Amsterdam, Philadelphia: John Benjamins.

Eccles, J.C. (1990). A unitary hypothesis of mind-brain interaction in
the cerebral cortex. *Proceedings of the Royal Society of London, B240*,
433-451.

Eccles, J.C. (1994). *How the self controls its brain.* Berlin,
Heidelberg, New York: Springer.

Beck, F.,& Eccles, J.C. (1994). Quantum processes in the brain: A
scientific basis of consciousness. In Naoyuki Osaka (Ed.), *Neural Basis
of Consciousness*. Amsterdam, Philadelphia: John Benjamins.