neurotransmitter storage (all or one?)

Theophilus Samuels theophilus.samuels at btinternet.com
Tue Aug 29 12:32:42 EST 2000


> As far as I know there is processing at all levels of the neuron

That is a very blunt statement - where is your evidence that processing (see
later) occurs on all levels of the neuron??

> In essence each neurone is a distinct computer performing many different
> calculations and passing it on in a digital and analogue fashion.

Probably, but remember every computer possesses a CPU, i.e. a brain - at
what level do we find the CPU in the neuron?? Perhaps you should say that
each neuron is a CPU instead (taking the computer analogy further)

Let us clarify something - that of the concept of information processing. At
this moment you are reading this paragraph. What is happening? To cut it
short, binary information, yes, 0 and 1's, are being transmitted to key
areas within the brain. Now, how is this information processed into the
reality that you and I are faced with. That is, the apparent ability of us
all to read and understand the meaning of the words in this paragraph - the
consciouss experience if you will? That is what the original discussion was
about - is this further processing done in a digital or analogue manner, or
using a mixture of both of them, or by something completely different?

> I don't actually understand what you mean by the phrase 'depends on a
> continuously variable quantity' and how that relates to neural
> computation.

What do you mean? Go to any scientific dictionary and look up the word
'analogue' - see the Larousse Dictionary of Science and Technology for
example. A continuous physical variable such as voltage or pressure can be
used to represent and manipulate the measurements it handles.

I think, before going any further, you need to define neural processing - is
it the same as information processing?

> To simulate a small area neural network you will need billions of
> these virtual neurones simulated within a computer in real time. And
> for a brain a much much larger virtual network.

Also, I get the impression that according to you, when one day a computer
engineer successfully links up the billions of 'virtual neurones' and
creates the larger virtual network that you believe it would be sentient.
Again, we run into trouble because of poor definitions - that of the word
brain. Is the mind and consciousness due to some physical phenomenon present
within the neurons of the brain? If so, is this some special property in the
way they handle information?

T.L.S.




James Teo <james at pc.jaring.my> wrote in message
news:39abad81.4819785 at news.jaring.my...
> On Mon, 28 Aug 2000 18:01:13 +0100, "Theophilus Samuels"
> <theophilus.samuels at btinternet.com> wrote with regards to binary or
> analogue processing in the brain:
> >The world at such subatomic levels is quite bizarre, as I'm sure you
know -
> >the simple idea of superposition is a good example. You see, the problem
> >faced by saying that the brain processes information in an analogue
manner
> >is that this by definition, this depends on a continuously variable
> >quantity. What is this? Is it the number of ions that participate in the
> >graded responses or the total number of dendrites that are affected by
the
> >electric fields set up by such conditions? Where does the level of
> >processing lie?? Of course, nobody as yet knows the answer (if this were
to
> >be true) and I suspect it will be a very long time until we do.
>
> I don't actually understand what you mean by the phrase 'depends on a
> continuously variable quantity' and how that relates to neural
> computation.
> As far as I know there is processing at all levels of the neuron. From
> the ion channels in the synapses to the ion channels in the nerve
> fibres, the protein machinery as well as the grading distances at
> synapses and neurotransmitter diffusion rates, and even glia. In
> essence each neurone is a distinct computer performing many different
> calculations and passing it on in a digital and analogue fashion. I
> don't see how this would prevent a silicon-based brain simulation
> since you could have each neurone function as a virtual program with
> protein, ion channel, conductance, etc subroutines passing information
> to another virtual neurone according to various modifiable rules
> (representing synapse-buoton size, synapse distance, glial
> interactions, receptor density, etc). The information passed on is
> graded, but the activity on the other virtual neuron may be any
> combination of digital and neural depending on the rules.
>
> To simulate a small area neural network you will need billions of
> these virtual neurones simulated within a computer in real time. And
> for a brain a much much larger virtual network. But why would you want
> to simulate the brain function in a digital computer? Instead I think
> computational neuroscience is about drawing lessons from the neural
> processing and applying it to computational understanding, rather than
> trying to copy the brain in a computer.
>
> >I think by now, we all accept that digital states are present within the
> >brain, just as analogue ones are. As pointed out before, inputs from the
> >periphery can only travel to the brain in trains of action potentials (ON
> >and OFF events) and somehow these must be intrepreted - processed - in
some
> >manner unknown to us all. Also remember, that the OFF states may just be
as
> >equally important as ON states. For example, the absence of AP could also
> >contribute to the final level of processing - as the composer Webern said
> >'the rests are just as important as the notes'.
> >
> > To conclude, the brain may not just process information by either
analogue
> >or binary means, but in fact there may exist a continuum between the two
> >states where the brain can utilise X amount of analogue and Y amount of
> >binary processing, such that X + Y = 1. The possibilities are amazing
when
> >one thinks about it - it is one of the reasons I enjoy Neuroscience so
very
> >much.
>
> Well, that is quite a succint way of describing it, although I think
> you might be mixing some terms occassionally. I sometimes get the
> impression you mean neural processing when you say brain function, and
> vice versa.
>







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