From: Martin Striz (email@example.com)
Date: Tue Feb 01 2005 - 18:21:02 MST
--- Phil Goetz <firstname.lastname@example.org> wrote:
> > True, but the brain is known to be highly
> > inefficient in many many areas,
> > e.g. (to choose a simple example) motion-direction
> > detection neurons that
> > are off by 80 degrees on average but are correct en
> > masse due to averaging
> This is not necessarily inefficiency. It may actually
> be very efficient. Neurons aren't "off by 80 degrees"
> so much as they have wide response zones and respond
> somewhat probabilistically within those zones.
> 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
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.
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