Re: Why Software Is Bad and What We Can Do to Fix It
From: Christopher Barber (cbarber_at_curl.com)
Date: 09/17/04
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Date: 17 Sep 2004 17:40:35 -0400
Traveler <traveler@nospam.com> writes:
> >> What did Gagne write that refuted the above? As any competent
> >> neurobiologist will tell you, the brain's reliability is a consequence
> >> of the stability and persistence of its timing. This is extremely
> >> important especially when one considers that there are close to 100
> >> billion cells and trillions of synapses to manage. Once the timing is
> >> properly set and corrected (during synaptic learning), it remains
> >> defect-free henceforth.
> >
> >I don't think this is true. Can you cite references?
> >
> >How do you explain forgetting?
>
> Forgetting is due to a slow decay of synaptic strength or to some
> physical malfunction. What does that have to do with timing or the
> reliability of the existing circuits?
You claimed that "once timing is properly set ... it remains defect-free
henceforth." What exactly does that mean? Isn't forgetting an indication
that circuits are not entirely reliable?
> >> The question is, why does the timing of brain and integrated circuits
> >> remain stable? Answer: Because the elementary processes are
> >> synchronous. This is clearly explained in the Silver Bullet article.
> >
> >It is clearly asserted, but not clearly explained. I don't think the brain's
> >elementary processes are really synchronous and had not seen any researchers
> > claiming that it was.
>
> You are kidding me? Why does one need someone else (a researcher) to
> prove something that is obvious?
It may be obvious to you, but it is clearly not obvious to the rest of us.
Yes, it is obvious that many neurons fire at the same time, but the rest
of your claims about stability of timing could use some more explaining.
> All neurons are synchronous, in the sense that they operate in parallel.
> They wait for something to happen and they react by firing.
Each neuron itself might be synchronous, although the fact that the
"something" you refer to may actually be some arbitrary threshold triggered by
thousands of inputs muddies the issue a bit. However, two neurons do not
always fire at the exact same time with respect to each other and are
therefore asynchronous.
> There are zillions of action potentials
> occurring in the brain at any one time, i.e., synchronously. What
> reference does one need to understand this simple fact?
If you simply mean "synchronously" to mean simply happening at the
same time without reference to the timing of the events, you should
use a different word or else risk confusing computer folks who expect
a more precise meaning.
> >I think you really need to provide more explicit
> >references to prior research to give your claims more weight.
>
> I don't think so. I cannot stand explanation by reference.
I cannot stand when people cannot back up their assertions with
hard evidence. You should also consider that some readers may
not already be well-read on matters of neuroscience and would like
to read some supporting material relevant to your claims.
> >> Gagne writes: "But the brain is also amazingly inefficient at what it
> >> does." This is nonsense, IMO. The fact is the brain is extremely
> >> efficient at what it does considering that the time scale of its
> >> elementary processors are on the order of milliseconds and that there
> >> are billions of signals arriving at the sensory cortex at any one
> >> time.
> >
> >That is true. I think he is arguing that the brain would provide
> >an inefficient architecture for computations that are currently done
> >by computers.
> ...
> >Any physical emulation of the brain would be massively
> >less parallel than the brain using currently available technology and
> >would thus be massively slower than the brain.
>
> Correct. But irrelevant to the issue of reliability.
Perhaps, but extremely relevant to the suitability of this paradigm for
real-world programming problems.
> >> Besides, even if this were true, inefficiency has nothing to do
> >> with unreliability. The reliability has only to do with timing, and
> >> timing is kept consistent by the brain's parallel architecture.
> >
> >I don't really grok this claim that "reliablity has only to do with timing".
> >It really doesn't make sense.
>
> The brain is essentially a discrete signal processing mechanism. It
> expects signals or spikes (hundreds of millions of them) to arrive at
> their proper time. If they don't, the brain will fail.
What exactly are you talking about? What exactly do you mean by "at their
proper time?" Are you talking about exactly what point of time a signal
reaches a synapse or the need for enough synapses to be stimulated at the
same time for a neuron to fire?
I still don't see what this has to do with reliability.
I know you think I am just being a pain, but after hearing a lot of
hand-waving brain analogies invoked by AI researchers and seeing it lead
nowhere, I am naturally skeptical.
- C
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