Re: Signal Processing (was BLUE GENE)

From: Richard Loosemore (
Date: Tue Apr 11 2006 - 23:05:37 MDT

Martin Striz wrote:
> On 4/12/06, Russell Wallace <> wrote:
>> On 4/12/06, Martin Striz <> wrote:
>> I'm curious, what parts of the complexity of neurons are needless?
> Why propagate a signal as a transiet voltage change rather than a
> direct electric (or electrochemical) current? Why use absurdly
> complicated intracellular signal transduction pathways? Why implement
> over 100 neurotransmitters when one will do just fine (modular
> specificity can be achieved through wiring or through postsynaptic
> receptor response)?
> Martin

I guess one answer to the first question is that the neural signal is
not *exactly* an electrical signal, it is a complex wave phenomenon in
the potassium and sodium channels in the neural membrane, mediated by
the electrical potential. The main drivers of the effect are a sudden
influx of sodim ions from outside the axon to the inside, and then a
similar but opposite flux of potassium ions from inside to out.

Net benefit from this? Not very susceptible to static electricity.
Great for keeping your brain stable in the face of a rather staticky
world. Another benefit, perhaps: whereas an electrical signal is
somewhat passive and might therefore degrade with distance travelled,
the action potential is actively promoted by the energy locked up in the
neural fiber ... so it travels without loss of strength.

If I thought about it more, I might be able to come up with other
functionally useful features .... I'm not an expert though.

As for having lots of neurotransmitters, it might turn out to be the
case that this is a way to implement several different functional
influences on the process of thinking. For example: allow the system
to do multiple relaxation along several dimensions simultaneously. Now
I don't know if that is how they are used, but it is a possibility, and
it might work very well.

Bottom line: might not be a good idea to second guess nature's designs
until we're very sure we know exactly how the thing works.

Richard Loosemore

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