Andrew Gyles <syzygium at alphalink.com.au> wrote:
> In article <1eltvig.1jzyjdf10kez7kN%harry at dherwin.org>,
>harry at dherwin.org (Harry Erwin, Ph. D.) wrote:
> > Here's my dumb question: why should neurons need a flip-flop memory
> > element? There's no evidence they're digital.
> > --
> > Harry Erwin, PhD, <mailto:harry at dherwin.org>,
> > Senior Lecturer in Computing at the University of Sunderland,
> > Computational Neuroscientist (modeling bat behavior) and
> > Senior SW Analyst and Security Engineer.
>> They are not strictly analogue, either, are they? A neuron either fires
> or it does not fire. There is no difference in the amplitude of
> individual impulses. Information may be encoded in the frequency of
> impulses in a 'volley', or in the length of time for which a volley
> lasts, so in that respect they are analogue.
Actually, they're a good deal more complicated than that, particularly
in the dendrites, and hardly digital. Note that action potentials are
not seen in the retina, and there is a lot of computation done there.
The timing and relative sequencing of action potentials matters a lot.
>> But something has to 'decide' whether a volley will start, what its
> frequency will be and when it will stop.
What's this about volleys? By the time a primary neuron recovers and is
ready to generate another action potential, the event is usually past
and done with. Of course, my interest is echolocating bats, with pulse
generation rates ranging up to 200/second. Think about it.
> The kind of flip-flop memory
> elements I described could help to make that decision. Whether what
> then happens is analogue or digital I am unable to say.
>> I am aware that my hypothesis is highly speculative.
> Andrew Gyles
>>> Sent via Deja.com
Harry Erwin, PhD, <mailto:harry at dherwin.org>,
Senior Lecturer in Computing at the University of Sunderland,
Computational Neuroscientist (modeling bat behavior) and
Senior SW Analyst and Security Engineer.