Received: by alpheratz.cpm.aca.mmu.ac.uk id AAA08037 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Sun, 6 Aug 2000 00:35:41 +0100 Message-Id: <4.3.2.7.2.20000805174233.00b0aef0@pop3.htcomp.net> X-Sender: mmills@pop3.htcomp.net X-Mailer: QUALCOMM Windows Eudora Version 4.3.2 Date: Sat, 05 Aug 2000 18:43:57 -0500 To: memetics@mmu.ac.uk From: "Mark M. Mills" <mmills@htcomp.net> Subject: RE: Simple neural models In-Reply-To: <4.3.1.0.20000725165641.00c30c70@pop3.htcomp.net> References: <A4400389479FD3118C9400508B0FF230040E66@DELTA> Content-Type: text/plain; charset="us-ascii"; format=flowed Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
At 06:38 PM 7/25/00 -0400, I wrote:
>I'm not suggesting an entire nerve cell takes on a single binary state,
>only that binary elements at the synapse level play key roles in
>electro-chemical signal processing. Specifically, I'm alluding to
>Kock's description of autophosphorylating kinases (Biophysics of
Computation).
>He suggested they are analogous to transistors. With a certain amount of
>voltage applied to them, they conduct. Without the voltage, they resist.
Derek disputed my interpretation of autophosphorylating kinases, so I wrote
Koch for clarification and received the following reply:
"yeah, a kinease is just a specific type of enzyme, so they don't conduct
electricity. So in that
sense your neurology pal is correct. Think of the autophosphorylation like
a button. You can press
it in with your finger and it remains in its depressed position until you
press it again and it
pops back to its original state. A neat molecule."
In reply, I asked for his opinion on the role autophosphorylating kinases
play in signal processing, but haven't received any answer.
After reading the Koch Lab's website (http://www.klab.caltech.edu/), I
contacted Gabriel Kreiman. According to his website, he had done some work
with kinases. I asked him if he could relate kinases to signal
processing. He replied:
"The role of kinases in signal processing is still unclear.
They are known to be involved in memory potentitation processes."
He pointed me to the paper: 'Tetanic Stimulation Leads to Increased
Accumulation of Ca++/Calmodulin-Dependent Protein Kinase II via Dendritic
Protein Synthesis in Hippocampal Neurons (1999)
(http://goethe.klab.caltech.edu/~gabriel/publications/camkii1.html)'
Kreiman coauthors.
Additionally, 'Long-Term Potentiation: What's Learning Got To Do With It?'
by Tracey J. Shors & Louis D. Matzel (1997)
http://www.cogsci.soton.ac.uk/bbs/Archive/bbs.shors.html
has an interesting survey of work on memory models, including suggestions
that kinases are involved.
Based on all this additional input, I want to thank Derek for pointing out
the errors in my characterization of autophosphorylating kinases. We don't
know what they do. We only know they are involved in neural processes and
flip/flop between two stable states at a speed about as fast as the
quickest reflexes.
Mark
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