"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?
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.