inside a neuron

Hi, Tim --
The whole group might be interested in this:

Yes, E. coli is a single cell. And yes, plants are control systems, too. I once encouraged a horticulturalist on CSGnet to write a book on "Plant Behavior," of which there is quite a lot. It never got done, but would be interesting. Think of sunflowers tracking the sun. Or a mimosa:

This YouTube page shows that the mimosa is sensitive both to light and to touch, seeking light and avoiding touch.

In E. coli, the signals are "messenger molecules" inside the cell body. Perceptual signals are molecules which come from receptor molecules in the membrane when an external substance "docks" on the receptor molecule. There is an amazing amount of structure and signalling inside a cell, human cells and all others, too. Apparently, all organisms are hierarchies of negative feedback control systems.




At 10:07 AM 12/7/2011 -0800, Tim Carey wrote:

Hi Bill,

OK, thanks. I'll mull this over - is e-coli a single cell? I was under the impression that it was but I've just realised I've never actually checked that out. And now I'm realising I've also always assumed that the control system model applied to plants too because they are living things. Is that reasonable?

On my assumption that cells were control systems, I figured the little single loop model (as in the live block diagram) would be a neat model for cancer and the apparent 'out of control' growth of the cells. Do these little single cells have processes that are biochemical equivalents of perception, comparison, and action? When cells start multiplying rapidly which is what I''m assuming happens in cancer (and I know almost nothing about cancer) has the equivalent of their reference changed or perhaps the gain of their output??

It is the case the we assume negative feedback is occurring at the level of DNA isn't it? I guess I didn't think it was too big a leap to suppose the same process was occurring in single cells.



Dr Tim Carey MAPS
Associate Professor in Mental Health
Centre for Remote Health and Central Australian Mental Health Service

Centre for Remote Health
a joint centre of Flinders University and Charles Darwin University

PO Box 4066
Alice Springs, NT 0871
Ph 08 8951 4700
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From: Bill Powers []
Sent: Thursday, December 08, 2011 1:08 AM
To: Tim Carey
Subject: Re: inside a neuron

Hi, Tim --

Good question: is a cell a living organism in itself, or only a
component of a living organism? Obviously there are control processes
inside a single cell, neural or any other kind. I've wondered,
"what's in it for the neuron?" Of course we have to avoid giving any
higher-order abilities to it, such as thinking or planning and all the rest.

>So, a neuron functioning as a comparator for example, receives two
>input signals and generates one output signal that is the difference
>between the two input signals. Does it do this as part of the
>process of keeping its own internal environment constant? So the
>incoming signals would act as disturbances and the output signal
>would be its action on its immediate environment to affect the input signals??

Maybe the error signal is a waste product and gthe comparator cell
eats perceptual signals and reference signals. Naw, I can't go that
far. Wrong analogy. Let's just say that its current organization is a
result of evolution and reorganization. Even if it started out, a la
Margolis, as an absorbed microorganism, it's not that any more. And
maybe never was -- it could just be an product of the factory called
a stem cell, from which many different kinds of cells are produced
through, I assume, reorganization. But it does have metabolism, so
it's alive to that extent ....


Hi, Henry –


The literature on plant behavior is enormous, starting and

Darwin. Someone probably reviewed it well

OK, I Googled “plant behavior review” and instantly got

And you’re probably too young to remember this:




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At 12:58 AM 12/10/2011 +0800, Henry Yin wrote: