From: tychay@juliet.caltech.edu (Chay, Terrence Y.)
Subject: brain rom and all that... just the obvious stuff
News-Software: VAX/VMS VNEWS 1.41    
Organization: California Institute of Technology
Date: Sat, 29 Aug 1992 09:10:00 GMT

  the brain as ROM? well the others have answered that far better than I.
P.S. if you believe the brain is read-only take some crack for a year
or two and see if your unaffected ;-), or howabout a couple zillion
volts across your brain?

  some people were asking about "how" we remember.... if you know tell me
i could always use a nobel prize. =]  
(though i would not place any money that memory is stored in RNA)

---------
and now for what you all know but i feel like saying anyways and if you
don't like it go to next "---------"

  there are two communication "styles" in the brain and the body.  the first
is electrical which Hodgkin-Huxley verified (nobel!), electrical signals
run down a neuron through a self propagating, regenerating action potential
"wave" cause by migration of K+ and Na+ ions (charges!) down the axon...

  ooo    ------> direction of propagation
 ooooooooooooooooooooooooooooooooooooooooooo<
  oooo         ^axon                    ^synapase (connection to other cell)
   ^^cell body

 at the synapse, the pulse cause an influx of Ca++ ions which activate
vescicle release (the second "style"- neurotransmitter chemicals)  which bind
to sites on the next cell (postsynaptic)  [p.s. sorry about the jargon, i
hate it myself also].  there is one exception known as gap junctions but
that is considered "primitive" (in evolutionary sense) and is not common.
gap junctions are electrical (style one).

 also there are hormones (like growth hormones) released by the pituitary
gland but i consider that of the second "style" since some neurotransmitters
are also hormones.

 for instance, Achetocholine(sp?) (ACh) is the most common "activating" 
neurotransmitter in the body (including activating muscle cells i think_
and some postsynaptic sites of ACh may be blocked by nicotine (hence the
term nicotine--hence, why we like tobacco).  (i may be wrong!)
  gamma-amino-butyric-acid (GABA) is the most common "deactivating" neurotrans-
mitter, i think alchohol affects GABA but i cant cite sources
  serotonin is a neurotranmitter pretty much brain local.  it affects sleep-
wake cycles in the brain and is affected by LSD.  LSD really is "dreaming
awake" and while i don't know if the myth that you can't fall asleep on
LSD is true, i could believe it.
  endorphins (sorry not familiar with proper names) are endogenous-morphines
that block pain in our body (ever heard of the placebo effect?).  obviously
morphine has a similar binding property that endorphins do.
  then there is always nerve gas...

please read disclaimer after my .sig

--------
  what this may mean for "jacking-in" (my opinions!)
  chemical application- i guess there are the following problems
     1) localization- how do i get the chemical "where" i want it?  in some
           cases the same neurotransmitter is linked to distinctly different
           functions. (i.e. schizophrenics on the "miracal drug" for a
           significant period develop twitches due to the drug affecting
           dopamine output necessary for initiation of movement... i think
           people with parkinson's disease take l-dopa right?)
      2) the message- how am i sure my chemical is sending the right "message"
      3) amount- the amounts of the chemicals are tiny.  some claim that only
           quantum mechanical models are reasonable at the synaptic junction
           (i have severe doubt since Katz's study of end plate potentials 
           seemed reasonable(Nobel!))
      4) application: how would you do it?  seems like an interesting line
           for you imaginative cp'ers out there.

  electrical-
      1) how?  accessing nerve fibres means poking the tissue surrounding
         a nerve bundle... some studies (forgot cites) show that that causes
         severe EAD (early axonal degeneration)
      2) gross stimulation? stimulation through potentials and currents(?)
         _outside_ the nerve bundle requires tremendous voltage (biological
         scale = mV so "tremendous means on the order of a volt) for any
         affect to the bundle.  plus it's nonlocalizable. + EAD.
      3) THE TEN MILLION DOLLAR QUESTION: what is the code? take a look at
         hubel and weisel's works on oriented cells in the primary visual
         cortex (Nobel!) and you'll get the difficulty of understanding a
         small portion of the information carried by the eye to the brain
         (a low level process!)

3 years ago a division of JPL (jet propulsions laboratory- who does all our 
unmanned space programs) put out a proposal on research to make "boxes" to
that would create "walking" in parapalegics.  when i saw their presentation
i wanted to kill them (they said marketable product out in 10 years,  10 years!
it would take 10 years just to test the box to make sure it wouldn't cause 
permanent damage to nerve cells- anyways the tech was/isn't up to it yet)  but,
i was doing work in EAD at the time so that's a really biased statement.
i don't know if the proposal passed.

at caltech there is a physics prof named Jerry Pine who is trying to make
nerve's communicate to semiconductor or vice versa... but i wasn't paying
much attention (and am too lazy)... but it seems to have application to
"jacking in" anyone read his papers (i can't say that i've even tried!)?

the big thing here at caltech seems to be Hopfield/Mead's analog VLSI design
they have a analog VLSI neural "eye" and a analog VLSI hodgkin-huxley "neuron"
(complete with Ca++ channelss) already out, and i think they are working on
an ear...  the "eye" is neural network oriented and is more useful for
study of Hubel & Weisel and its only possible application is possibly
for AI computers ("jacking in" *sigh*).  someone told me they showed it on
NOVA but i never watch science shows (again too lazy).

-------- 
this is my .sig, deal with it.

          -terrychay
                 TYCHAY@CITJULIE.BITNET
                 tychay@juliet.caltech.edu
--------

i welcome any corrections since ....

p.s. don't go spouting any of this shit to your friends.... for all i know
     i'm full of it - to be honest i never, myself, actually recorded
     a single action potential! (though it works -with a bit of tweaking- on
     the computer.)

--------
i welcome any opinions or thoughts or arguments!!!!

just because i use "big" words doesn't make me smart (in fact, it makes
me more stupid since i tend to hide behind the words instead of relying
on the *argument*)  in short, in my case, "those who say don't know, and those
who know don't say"  and i am _saying_ so obviously....

summary of this post:
  "full of sound and fury.
   Signifying nothing."

take care