neurotransmitter storage (all or one?)

Theophilus Samuels theophilus.samuels at btinternet.com
Sat Aug 26 13:12:52 EST 2000


 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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