Binary behaviour of some dendrites

Andrew Gyles syzygium at alphalink.com.au
Fri Sep 28 20:20:01 EST 2001

"Matt Jones" <jonesmat at physiology.wisc.edu> wrote in message
news:b86268d4.0109281042.6185f69a at posting.google.com...
> "Andrew Gyles" <syzygium at alphalink.com.au> wrote in message
news:<9om3lc$e05sl$1 at ID-94640.news.dfncis.de>...
> > In December 2000 there was some discussion in this newsgroup of my
> > hypothesis that mitochondria might act as flip-flop memory elements in
> > neurons.
> >
> > One counter-argument ran as follows: "Why should neurons need a
> > memory element? There's no evidence they're digital".
> >
> I remember that discussion. I hope I wasn't one of the people arguing
> that neurons aren't digital. I don't think this "not digital" argument
> is really a good argument against your hypothesis.
> My arguments would be this: OK, mitochondria might act as flip-flops.
> But a) do they really do that? b) If they do do that, is that behavior
> actually -used- by the neuron to store information that's relevant to
> how it acts as a signaling element within the circuit, and c) there
> are lot's of other ways that a neuron could incorporate flip-flop
> types of behavior, e.g., latching of CAM kinase II into an
> autophosphorylated state, expression of previously silent AMPA
> synapses, transcriptional regulation of genes for K channels, etc etc
> etc.. Practically -any- neuronal behavior could potentially serve as
> the substrate for a flip-flop role if regulated appropriately. So why
> is the mitochondria-based mechanism more plausible or likely to be
> useful to the neuron than any of these other, more well-established
> mechanisms for generating the same sorts of behavior?
> Cheers,
> Matt

Thank you for your comments. All of the questions you posed are valid and
would have to be answered by experiment before my hypothesis was accepted or
rejected. Perhaps I can attempt a preliminary answer to a couple of them.

Transcriptional regulation of genes for K channels would be a slower form of
"switching" than the "flip-flop" action of mitochondria that I postulated,
would it not, and speed is important in information processing. Perhaps the
"expression of previously silent AMPA synapses" would also take longer than
the action I suggested.

On the other hand, latching of CAM kinase II into an autophosphorylated
state would perhaps be quicker than the "flipping" or "flopping" of a
mitochondrion. And as you remarked there are other alternative possible
switching actions. My hypothesis is just one of many and will have to face
the test of experiment.


Andrew Gyles

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