McCrone replies

mailto: j.mccrone@btinternet.com
  web site: http://www.btinternet.com/~neuronaut/

There has been some discussion in your group on an article I wrote for the
New Scientist magazine on a dynamical view of the neural coding issue
(check my site for a copy of the article). Also some of you have emailed to
ask if I am aware of PCT theory. The short answer is no - but I have done a
quick skim job as a result.

You seem quick to dismiss the dynamics story - and you are right in that
most of those who call themselves dynamic don't really get it. Only a very
few combine both a grasp of dynamics and the necessary in-depth knowledge
of how the brain is organised and so can talk about the very particular
dynamics of the brain (its hierarchical organisation, its subcortical
"bottlenecking" organs, its multi-dimensional plasticity, etc). But there
is something brewing there.

Personally, I am sympathetic to some of the PCT themes. The book I have
coming out in October is really all about how consciousness is not a state
of contemplation but a reaction. Brains are designed to formulate
intentions and actions. So in some sense, the processing is controlled by a
goal of "best action". But it strikes me that PCT is a very
one-dimensional, mechanical, way of describing what takes place. Sure you
will tell me that it is a proper theoretical construct whereas I just talk
in easy analogies. But to me, that desire for something rigid is just part
of the whole reductionist science problem. Dynamism is about learning to
live with a way of doing science that is more organic, more flexible -
looser so that it can ultimately wrap tighter around its subject.

Anyway, a couple of things that may not be getting their proper emphasis
within PCT. Where do you stand on anticipation? The brain takes time to
evolve a reaction to whatever is just happening - the psychophysics says
this is at least a tenth of a second and probably half a second (to go
through all the stages). This creates a gap. The brain gets over the gap by
making predictions (or forming plans, expectations, reafference messages,
priming, mental images, inklings and intuitions, or whatever you want to
call it).

The second big thing is that the brain is heavy with habits. The first time
the brain has to deal with a situation, it does so in a "conscious" (that
is globally exploratory, highly unstable, third of a second to stabilise)
sort of way. Then very quickly, with experience, it "shrinks down" to a
more habitual solution (the population of neurons involved is whittled down
to a skeleton crew that can do the job swiftly and reliably, the habit
pattern also sinks down to "inhabit" lower levels of the hierarchy such as
the basal ganglia/insula cortex). And these habits are sensory as well as
motor (no real hard distinction anyway if you are a true dynamicist). So a
new-born kid is born pretty bare of circuitry and then learns how to
respond to the world. It experiments with the perceptual categorising and
thought and motor responses needed to make itself more adapted to the world
it finds itself in. Within a few years, this fat layer of habitual reaction
can deal with most of what life throws at it, leaving "consciousness" (the
most globally coherent shift in brain state during a particular moment) to
tackle the very small residue of novelty or significance left over.

This sets up a general cycle of processing. The brain generates a state of
anticipation (what it wants or expects to happen during the coming moment),
the moment then starts to happen and as much of possible gets dealt with at
a preconscious, habitual, level, then the bit left over is escalated
(prefrontal lobes, cingulate cortex, basal ganglia loops) so that it
receives special attention. It becomes the nub of the moment and creates a
wash of activation back down the brain hierarchy that stimulates all the
associations, thoughts and motor planning that we loosely call anticipation
- the wheel has turned a full circle.

At first glance, PCT does not seem to accommodate anticipation (which is
all about open destinations rather than controlled end states), nor the
habit vs focal consciousness trade-off in the processing loop. Thirdly, you
seem to be pushing a systems level view of brain function without actually
talking about any brain structures themselves - is there any neuroscience
in all of this?

Judging by the rather evangelical tone of some of the postings I have read,
I'm certain I will shortly be getting a rather blunt reply.

Cheers all!

···

from: John McCrone -- science writer

[From Bruce Nevin (980102.1424)]

(John McCrone Fri, 2 Jan 1998 00:30:40 GMT) ---

Hello, John. Welcome.

I'm sure others will respond much more ably than I, a very "junior" member
of the group, but in the absence of any response visible to me (maybe the
listserv host is down?) I want to offer a couple of thoughts in reply.

PCT doesn't have much of anything to say about consciousness or awareness
at this point. I suppose it could very well be emergent in the way proposed
by dynamicists, even if what is going on under the surface of the
metaphorical pond is gazillion elementary control systems (ECS) controlling
their inputs relative to reference signals received from higher-level ECSs.

it strikes me that PCT is a very
one-dimensional, mechanical, way of describing what takes place.

A dynamical account is also going to refer ultimately to mechanism.
Distinguish carefully between the rhetoric of "mechanistic reductionism"
and the undeniable fact that whatever is going on is implemented in cells
and organs which by their "mechanical" interactions bring about the effects
that we observe. And before you decide that PCT is artificial and limited
(I suppose that is what "one-dimensional" and "mechanical" mean), take the
time to work with and understand the demos that are freely available. In
particular, understand the significance of creating a model that behaves
like a living organism (for the behavior being modelled) with greater than
95% accuracy, running in digital simulation on a PC.

You are a science writer. There is a fantastic story here, if you can see
it. This is possibly the most important fundamental development in science
since Copernicus--a principled basis for understanding living organisms,
what distinguishes them from non-living things, what they are doing from
their points of view that constitutes living. That, not philosophical
commitment, certainly not career advancement, is the excitement behind what
you perceive as evangelism.

A comment now about qualities of discourse that you may have noticed in
your quick skim. PCT is difficult for people to deal with who have invested
time and energy into learning earlier sciences dealing with living things.
It seems irresistable to try to assimilate it into what is familiar. This
leads to some prickly exchanges that might seem to reduce to semantic
quibbles. For example, you said:

Brains are designed to formulate intentions and actions.

The experimental evidence shows that actions are not formulated, they
reflect continuous trial and error doing whatever it takes to make
perceptions match intentions. "OK, whatever," you might say. Cheesh, why
are they so thin-skinned about a word like "formulated"? The brain does
stuff, and an action comes out. What's wrong with saying the brain
formulated the action? It must have, right? But what is at issue is the
fundamental insight of PCT, that behavioral outputs are not controlled,
they are *means* of controlling perceptual inputs. Experience over 40 years
has shown that when people talk in linear causative terms ("the brain
formulates actions", "stimulus from the environment", "response of the
organism") they have not negotiated this fundamental insight and are trying
to assimilate PCT into ways of thinking that are indeed limited,
artificial, one-dimensional, and mechanical.

Please, do more than "a quick skim job."

Here is a summary of URLs that Rick posted a little while ago:

The CSGNet home page:

  http://www.ed.uiuc.edu/csg/

Rick's site, with lots of demos

  http://home.earthlink.net/~rmarken/

Rick's introductory paper:

  http://home.earthlink.net/~rmarken/SP.html

Bill Powers' site:

  http://www.frontier.net/~powers_w

Ed Ford's site for applications to counselling and other resources, such as
papers by Tom Bourbon:

  http://www.edford.com/

  Bruce Nevin

[From Rick Marken (980102.1420)]

Bruce Nevin (980102.1424) to John McCrone --

Hello, John. Welcome.

I'm sure others will respond much more ably than I, a very
"junior" member of the group, but in the absence of any
response visible to me (maybe the listserv host is down?)
I want to offer a couple of thoughts in reply...

Well, I think you deserve a big promotion (from "junior" to
"distinguished"?) after that post. Bruce. It was intelligent,
accurate and downright moving. Thanks.

It looks like 1998 is going to be a very good year for PCT.

Best

Rick

···

--
Richard S. Marken Phone or Fax: 310 474-0313
Life Learning Associates e-mail: rmarken@earthlink.net
http://home.earthlink.net/~rmarken/

[From Bruce Gregory (980102.1750 EST0]

Rick Marken (980102.1420)]

Bruce Nevin (980102.1424) to John McCrone --

Hello, John. Welcome.

I'm sure others will respond much more ably than I, a very
"junior" member of the group, but in the absence of any
response visible to me (maybe the listserv host is down?)
I want to offer a couple of thoughts in reply...

Well, I think you deserve a big promotion (from "junior" to
"distinguished"?) after that post. Bruce. It was intelligent,
accurate and downright moving. Thanks.

It looks like 1998 is going to be a very good year for PCT.

The Bruce's are planning a major advance... (Well, _some_ of the Bruce's...)

Bruce