From: Phil Goetz (philgoetz@yahoo.com)
Date: Tue Feb 01 2005 - 19:52:35 MST
--- Martin Striz <metastriz@yahoo.com> wrote:
>
> --- Phil Goetz <philgoetz@yahoo.com> wrote:
>
> > Neurons use redundancy to tolerate noise. In
> > exchange, they can use much, much lower voltage
> levels
> > (by about 5 orders of magnitude) than integrated
> > circuits do, because they don't need to be
> completely
> > reliable. This may lead to lower overall power
> > requirements for a computation. You could work
> out
> > the numbers for known systems, but it wouldn't be
> > easy.
>
> When you say 5 orders of magnitude, are you taking
> into account the distance?
> A 100 mV difference across a 5 nm membrane
> translates into about 100,000 V per
> centimeter (Cf. MBoC, Alberts et al.). There's
> actually a lot of electrical
> potential energy in that noggin.
>
> Martin
I hadn't thought of that. Would you measure the
distance across the membrane, or the distance
that the signal travels down the neuron?
The human brain runs on about 75W, which is less
than a desktop PC. Its computing power is believed
to be orders of magnitude greater than the power
of that desktop PC. So the brain still comes out
on top.
- Phil
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