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From: wmills@netcom.com (William J. Mills)
Subject: Re: 100 Billion Nuerons
Message-ID: <wmillsCswFJ6.Er@netcom.com>
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References: <wmillsCsrLH9.Dp0@netcom.com> <ZByDPc2w165w@sfrsa.com>
Date: Wed, 13 Jul 1994 21:54:41 GMT
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Neurons actually do a time dependant re-uptake of the neortransmitter.  
This means that a  saturated neorn that gets another pulse that puts it 
over its firing threshold will fire.  So a lot of pulses coming up the 
line will fire the next neuron, but a single synapse firing will not do 
it. There are networks that use a bias-to-0 (not the correct term) model 
that moves each such node toward a 0 state at each time step.

It can also happen that a neuron will use up all of the neurotransmitter
and not be able to fire anymore until it takes some back in,
which is kinda neat too.  It means that you get a saturation where you 
'get used to' something.

Will the mechanism be that ugly, because you will probably be visiting
every node anyway won't you? Otherwise you have to track what nodes you 
have touched with activation and only process those, which seems uglier 
that hitting the whole net and doing a decrement on a given time interval.

Please pardon the brain cramp in my previous post differentiating between 
the synapse and the neuron, they will both have the same firing 
state/value. !!! Reading further in my own post I see more dreck...

Is is valid to flame myself?

bsmall (bsmall@sfrsa.com) wrote: 
: wmills@netcom.com (William J. Mills) writes:
: > The granularity needed would seem to be fairly small but is also time 
: > dependent right?  The counter could increment based on other neurons and 
: > decrement back to 0 over time.  The counter basically being a 'saturation 
: > of neurotransmitter' which is re-absorbed from the synapse.  Is neuron 
: > firing based on the sum of all of the synapses?  If so then the synapses 
: > might be simple while the whole neuron obeys a slighlty more smooth 
: > behavior with a few more bits of representation for the neuron itself.

: I'm not sure. When I originally thought of this kind of system
: I assumed I would need a mechanism to bleed off the counters.
: What a pain though because you would need to touch every cell
: in the system periodically. Another way is to somehow time stamp
: the cells counters and when a new stimulus comes into the cell,
: you ask if the old counter value is too old, and make a decision
: based on the count and how old the count is.
:  
: I'm thinking now that you really don't need to bleed off the 
: counters at all. So what if a seldom visited cell ocassionally 
: goes off. In the grand scheme of things, this once in a great 
: while shouldn't effect the outcome of the thinking process. It's
: the cells that are firing a lot that really matter.
:  
: Is neuron firing based on the sum of all the synapses? I think 
: so despite the earlier talks in this discussion about quatum 
: physics, etc. There are definetely a lot of things going on but
: we need to concentrate on the major player(s). One interesting 
: neural tissue dilema is the inhibitor synapse. What on earth does
: this do in our brains or in bee brains? Do we need inhibitors to
: create a stable system?
:  
: Brad Smallridge
: bsmall@sfrsa.com
