Basic Neuron Questions

Didier A. Depireux didier at rai.isr.umd.edu
Thu Apr 10 10:44:25 EST 2003


John H. <johnh at faraway.xxx> wrote:
> Just for once, could someone say, "it's really quite straightforward." I
> wonder how often lecturers in neuro related jazz feel threatened by their
> students ... .

So in a sense "it's really quite straightforward." The way you phrased your
question prevented me from saying that!

What I mean is that, people have been arguing about whether it's a time code
or a rate code. And the truth seems to be a lot simpler, and neither rate
nor time codes. It's in between, one spike per relevant time-scale. 

If an engineer had been asked to design a system using spikes to communicate,
he would have chosen either a rate or a timing code of sorts. The system
designed by evolution is both more complex (because the relevant time-scale
will depend on what is being encoded) and a lot simpler (you can use the
same coding scheme for any sensory input). It's economical (precise timing
requires a high metabolic rate, population code requires a lot of neurons)
and quite flexible.

I don't know your background, John. But maybe you don't appreciate how very
very little we actually know about the brain. Our current brain research is
to a large extent like butterfly collecting. We arrange the facts we observe
according to their colors, size, shape, and put them in different boxes. But
at a fundamental level we have no idea. 

						Didier

-- 
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