neurotransmitter storage (all or one?)

Richard Norman rsnorman at mediaone.net
Sun Aug 27 18:13:54 EST 2000


There are several major assumptions in your way of thinking that I don't
really understand.  The question about creating an "artificial sentient
being" only the ultimate.

Why should graded or analog processes be any less knowable or understandable
than discrete or digital ones? In the Newtonian universe, everything is
continuously variable -- space, time, mass, force, momentum, energy.
And phenomena in the macroscopic world of modern physics are so large
compared to quantal steps, that they might as well be continuously variable.
That doesn't mean that these things are incomprehensibly complex, only that
we use a real number, a continuously variable measure, to describe them.
And nothing in our behavior is really discrete. I am not "happy" vs. not or
"angry" vs. not.  Instead, my behavior shows differing degrees of happiness
or anger that fluctuates all the time.  So I just am not sure why the
absence of
digital states makes any difference in how we see or understand the world
around us.

As for two questions you raise:  "How can a seemingly random event give rise
to the coherence patterns of mental activity" or can an "artificial
sentient being be created using ... computer technology" -- these
are not really questions that we are anywhere near ready to approach.
I would prefer rephrasing them:  "How can the big bang give rise to
the coherence patterns of mental activity -- and to the apparently sentient
beings we claim to be?"  The answer, of course, lies in evolution.  But
there are a lot of interesting details left to be worked out!

"Theophilus Samuels" <theophilus.samuels at btinternet.com> wrote in message
news:8oc45p$rqp$1 at plutonium.btinternet.com...
> Tell me something, I've just finished reading your reply and I would like
to
> know what you think of the following. If the brain processess information
in
> both analogue and binary forms (more in the case of the former, according
to
> u ;-)), then is it truly a hopeless cause to ever think that a artificial
> sentient being can be created using the limited computer technology we
have
> access to??? I mean, a graded response must on the molecular scale be
> incomprehensibly complex on each occasion that it is initiated, and thus
no
> correlation will be ever be found between one graded response and the
> situation that it may produce (i.e. an emotion for example) - I suppose
this
> also depends on whether u believe that information can be processed on
such
> a microscopic scale.
>   I respect and know that the brain does indeed possess graded responses,
> and as I have said, each one must on the molecular scale be unique and
thus
> makes understanding the phenomenon of consciousness totally beyond our
> grasp. Does this make sense? How can a seemingly random event give rise to
> the coherence patterns of mental activity? Is this question answerable?
>
> T.L.S.
>
> Richard Norman <rsnorman at mediaone.net> wrote in message
> news:iEUp5.1660$_e4.240409 at typhoon.mw.mediaone.net...
> > I think you are missing the importance of what we two Richards are
> > saying.  The fact is that there are, indeed, large numbers of neurons
> > that work completely without action potentials in any form.  And many
> > neurons that do produce action potentials still interact with
> > dendro-dendritic synapses that are completely graded.  It is quite
likely
> > that most of the important "computations" done by the nervous system
> > are in this graded format.  Only when a message must be transported
> > some distance is it translated into the binary form of the all-or-none
> > action potential.
> >
> > "Theophilus Samuels" <theophilus.samuels at btinternet.com> wrote in
message
> > news:8o91ca$6ro$1 at plutonium.btinternet.com...
> > > I understand what you are trying to say and I agree with you. The
> original
> > > thought was that the 'brain is sorta like a computer that is not based
> on
> > > binary' - what exactly was this fellow trying to say?
> > >   Sometimes, one should break down a problem into its simplest
> components.
> > > The neuron initiates an action potential at the axon hillock and this
> > > 'event' can be manipulated by other synapses, be they inhibitory or
> > > excitatory via dendrodendritic, axosomatic or even axoaxonic
> interactions.
> > > Here is a basic fact, only when the potential difference across the
> > membrane
> > > component reaches the threshold potential is an action potential
> > initiated -
> > > given, that graded action potentials can occur without reaching this
> > > potential, but again remember, in the brain what is the use of a
graded
> > > potential in the realms of information processing?? Here is where I
> think
> > we
> > > have got our wires crossed, I am referring to the way information is
> > handled
> > > within the brain.
> > >   Thus, I am referring to is the 'all or nothing' response generated
by
> > > neurons in the form of the overstated AP. This is what is ultimately
> used
> > to
> > > carry information from one part of the brain to the other! For
instance,
> > > information coming in from the left visual field is processed by the
> right
> > > occipital cortex and vice versa. Thus, the only way for both occipital
> > areas
> > > to communicate with each other is via the corpus callosum, or more
> > > specifically via AP travelling through these myelinated axons - there
is
> > the
> > > key, ACTION POTENTIALS, or in computer terms ON events, there is no
way
> > that
> > > graded AP can give rise to corticocortical interactions on such
scales.
> > >   To close, what I am saying is that ultimately the first and foremost
> > level
> > > of processing within the brain can only be the ON or OFF AP fired at
> > > DIFFERENT FREQUENCIES - there is where we shall find the greatest
> > > difference, a difference that no computer engineer will probably be
ever
> > to
> > > replicate, that of AP firing frequencies to process information.
> > >
> > > T.L.S.
> > >
> > >
> > > "Richard L. Hall" <rhall at webmail.uvi.edu> wrote in message
> > > news:v0422080ab5cc75761001@[146.226.154.76]...
> > > >
> > > > Yep...most brain cells use grade synaptic transmission driven by
> > > > slight changes in potential.  Even at "resting" potentials some
cells
> > > > release neurotransmitter.  Thus, synaptic interactions merely modify
> > > > a continuous process.  This has the advantages of:
> > > >
> > > > 1.  reducing the response time of the system,
> > > > 2.  reducing the requirements for large signal to noise resolution
> > > > while increasing
> > > >        information content,  and
> > > > 3.  averaging the rates of energy consumption so you do not have
> > problems
> > > like
> > > >       running out of fuel just when you need maximal computing
power.
> > > >
> > > > The response of an on/off system driven by action potentials would
be
> > > > complicated by refractory periods and make it hard to summate
> > > > information....timing is everything.
> > > >
> > > > A system that is constantly transmitting information essentially
> > > > integrates signals and noise.  Since noise is random, it falls out
> > > > over time making it possible to detect smaller signals.  As a bonus,
> > > > a constantly active system can either increase or DECREASE in
> > > > activity giving even more flexibility and information value.
> > > >
> > > > The brain has virtually no energy reserves and without this
> > > > adaptation, a sudden increase in energy demand would be fatal.
> > > >
> > > > Nifty stuff this evolution.
> > > >
> > > > rlh
> > > >
> > > > >Surely it IS correct.  Action potentials are widely misunderstood
to
> be
> > > > >the be-all and end-all of nervous system information processing.
> They
> > > are,
> > > > >indeed, useful and important for transmitting information over any
> > > "large"
> > > > >distance, that is a few millimeters or more.  But at the cellular
> > level,
> > > a
> > > > >few
> > > > >millimeters is an enormous distance and graded "analog" potentials
> > along
> > > > >with graded (analog) transmitter release form a large portion of
the
> > > > >information processing in local circuits.  The best example of this
> is
> > > > >perhaps
> > > > >the vertebrate retina, where the receptor cells (rods and cones),
the
> > > > >horizontal
> > > > >cells, and the bipolar cells all do their thing without action
> > > potentials.
> > > > >The
> > > > >amacrine cells produce half-hearted action potential and it is only
> the
> > > > >retinal
> > > > >ganglion cells, who must send their output a long distance down the
> > optic
> > > > >nerve, that produces honest-to-goodness classical action
potentials.
> > > > >
> > > > >And in days past, there were large numbers of analog computers in
use
> > > > >doing all kinds of engineering computations and simulations --
adding
> > and
> > > > >subtracting, multiplying and dividing, even integrating and
> > > differentiating
> > > > >in
> > > > >the solution of complex systems of differential equations without
the
> > > need
> > > > >for a "On/Off" events.  Indeed, the very term "digital computer"
was
> > > > >necessary
> > > > >to distinguish the newcomers from the ordinary, more common analog
> > > > >variety.
> > > > >
> > > > >
> > > > >"Theophilus Samuels" <theophilus.samuels at btinternet.com> wrote in
> > message
> > > > >news:8o6f77$ri1$1 at plutonium.btinternet.com...
> > > > >  > > > It sounds as though the brain is sorta like a computer that
> is
> > > not
> > > > >based
> > > > >  > on
> > > > >  > > > binary.
> > > > >  > >
> > > > >  > > Right.
> > > > >  >
> > > > >  > Surely that is incorrect? The fundamental principle used by
> > computers
> > > > >relies
> > > > >  > on 'ON' and 'OFF' events, or in binary form, 1's and 0's. Now
> > > consider the
> > > > >  > neurons working within the brain. Essentially, all they do is
> > > initiate
> > > > >  > action potentials that either produce excitatory or inhibitory
> > > responses -
> > > > >  > 1's or 0's. Thus, you can actually say that the brain does
indeed
> > > work on
> > > > >a
> > > > >  > binary system IN principle. The MAIN difference between the
> binary
> > > system
> > > > >  > used within a CPU and a brain, is that neurons are capable of
> > firing
> > > at
> > > > >  > differing rates, i.e. information in the brain is FREQUENCY
> coded.
> > So
> > > to
> > > > >  > reiterate, the firing of neurons does indeed use a binary
> principle
> > > to
> > > > >  > create, well...., you or I.
> > > > >  >
> > > > >  >   T.L.S.
> > > > >  >
> > > > >  > <dag.stenberg at helsinki.nospam.fi> wrote in message
> > > > >  > news:8o55if$nvm$1 at oravannahka.helsinki.fi...
> > > > >  > > Phoenix <phoenix42 at uswest.net> wrote:
> > > > >  > > > It sounds as though the brain is sorta like a computer that
> is
> > > not
> > > > >based
> > > > >  > on
> > > > >  > > > binary.
> > > > >  > >
> > > > >  > > Right.
> > > > >  > >
> > > > >  > > > Since the computers we
> > > > >  > > > currently used are binary based, I wonder if we'll have to
> > > develop new
> > > > >  > > > computers that aren't binary based ...
> > > > >  > >
> > > > >  > > Before digital computers, there were analog computers.
> > > > >  > >
> > > > >  > > Dag Stenberg
> > > > >  >
> > > > >  >
> > > >
> > > > Richard L. Hall, Ph.D.
> > > > Comparative Animal Physiologist
> > > >
> > > > University of the Virgin Islands
> > > > 2 John Brewers Bay
> > > > St. Thomas, U.S.V.I. 00802
> > > >
> > > > 340-693-1386
> > > > 340-693-1385 FAX
> > > >
> > > > rhall at uvi.edu
> > > >
> > > > "Live life on the edge...the view is always better"  rlh
> > > >
> > > >
> > > > ---
> > >
> > >
> >
> >
>
>
>
>











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