ccastjr@prism.gatech.edu (10/09/90)
[Moderator's Note: The issue of neural interfacing may or may not be
relevant to this newsgroup's users. The following article is signi-
ficant because of its source and its claims. However, I would like
to hear from the community of users how much they would like to pursue
this line of inquiry. I'm currently disinclined to continue these
discussions of relatively far off possibilities and to concentrate on
today's technology and challenges, but your opinions will determine
if and where the neural interfacing continues. -- Bob]
I wasn't quite sure where to put this, but since I don't know of
any bionics/cybernetics groups, I decided to post it here.
The first part of this is from the August 1990 UNIXWORLD, page 160:
"New developments in the fields of electronics and bio-
chemistry are converging to make it practical to electronically
tie into the signals carried by individual nerve fibers.
MD's and EE's at Stanford University have made permanent
connections (already over a year old and still operating) to the
leg nerves of rats. Their device is a microchip that contains
1024 iridium-lined through-holes, each electrically linked to an
external conector. The rat's nerve is cut through, the chip
inserted between the cut ends, and as the nerve fibers regenerate
they grow through the chip's holes, with each hole connecting to
a single nerve fiber.
Experiments have accurately read pulses traveling up and
down the nerve fibers. The researchers have also sent thier own
pulses down the fibers to move the rat's leg. By summer 1991
they expect to be testing a self-contained implant-a chip that
transferes signals in and out of the body via and integrated radio
transeiver.
Stanford's work has been limited to the peripheral nerves
so far, because in mammals the central nervous system does not
naturally regrow to any significant extent after being severed.
But scientists at the University of Zurich recently demonstrated
that the proteins that inhibit regrowth can be neutralized by
injecting a monoclonal antibody. Rats they've injected have been
able to regrow severed spinal cord nerves up to a centimeter or
more-ample for growing through the holes in Stanford's chip.
Stanford is focusing its development efforts on the ovbious
use for this technology: giving amputees life-like control over
computerised artificial limbs. just as promising, though, are
implants in healthy users to give them fine-scale remote control in
situations which are presently limited to clumsy glove techniques.
Well before the middle of the decade, these chips could be replacing
mechanical glove arrangements in hazardous areas (space suits,
glove-and-window boxes in chemistry and nuclear labs), and electronic
sensor gloves that attempt to give hand-like control over long
distances or in microscale work."
First, the obvious uses, after the directly stated ones, could include
the "man amplifier" suits in stories such as "Starship Troopers", and "Aliens",
and a few other places. But when you think of the applications to VR and
simular work, it becomes truely revolutionary.
If the system is able to block regular nerve pulses (either by generating
pulses of interference, or by literal blockage), then a state of simulated
sensory depravation could be induced. Then, after mapping the eye
transmissions along the optical nerve, a full pseudo-sensory environment could
be induced. The outgoing body reactions could be handled in the same way
the sensory input is handled. By blocking signals to muscles after they have
been read, the system could send the intended movements into the virtual
reality environment.
Even some of the other systems of the cyberpunk fiction could be done
with these implants. Direct interaction with machinery such as a car could
speed up reaction times (by eliminating the time it takes to actuate the
muscle). It could also be used to prevent sensory overload in pilots by
giving them more direct control over several components, removing clutter
from the cockpit. Or even putting a window-based system in a persons field
of view that could be used for everything from sales records to aiming a
gun (and you thought a heads up display was fancy).
Emporers Thought for the Day: | John E. Rudd jr.
Only the insane have the strength to prosper; | ccastjr@prism.gatech.edu
Only those who prosper judge what is sane. | (ex- kzin@ucscb.ucsc.edu)
#include<std.disclaim> Send all comments, flames, and complaints to /dev/null.cygnus@cis.udel.edu (Marc W. Cygnus) (04/29/91)
Over the past week or so I've seen a few articles speculating on the progress
of the state-of-the-art in neural interfacing; following is some information
on "current" (mid-1990) research which I hope will be useful to anyone
interested in this field. (I certainly am... you could call it a burning
obsession of sorts :-) References are at the end of the posting.
In the May 1990 issue of _Science_, Science intern Sarah Williams reports on
a neural interface device developed at Stanford University [1]. The report
contains information presented by Gregory Kovacs at a 1990 plastic surgeons'
meeting held in May in Washington, D.C..
Apparently, she slightly misrepresented a few details in the report, because
in the June issue there's a letter from Kovacs in which he "[clarifies]
some statements made in... [the] article..." [2]. (nothing major, just
details)
Here is a summary of the information in the article, corrected where
necessary by drawing from Kovacs' letter:
Gregory Kovacs (Stanford University), along with Joseph Rosen (Stanford),
Bernard Widrow (Stanford), and Chris Storment (Dept. of Veterans Affairs)
have tested a neural interface chip which allowed recording of action
potentials from individual neurons in their experimental setup.
The chip was a little slice of silicon onto which a square array of 1,024
iridium microelectrodes were "stenciled." Then, a "high-performance plasma
etching process" [2] was employed to drill tiny holes through each pad and
through the chip, after which the entire chip was coated with silicon
nitride.
In their experimental setup, they implanted the chip in a rat's leg by
severing a nerve (presumably a "well-known" peripheral nerve), inserting
the chip in the cleft, and allowing the nerve to regenerate; during the
regeneration, individual nerve cells grew through the holes in the chip,
thereby providing a microelectronic link to each axon's activity.
Kovacs says in his letter,
We make no claim to have been able to stimulate "individual neurons."
While this may be possible with our device, our initial experiments
were not designed to test this. In the pilot study, we demonstrated
recording from, and stimulation of, peripheral nerves. We believe
that we were able to _record_ action potentials from individual
neurons. However, there is a big difference between stimulating and
recording. Current work is focused on determining how selective the
devices are in both of these modes. [2]
The last paragraph of his letter is perhaps more important to those of us
wishing to understand the state of progress in this field. He says,
Attempts to fabricate and use such neural interfaces are not new.
Since the early 1960s experiments have been conducted along those lines,
but only recently have fabrication techniques been developed that allow
devices to survive in the body for extended periods. Interfacing to
the nervous system will undoubtedly be done sooner or later, with or
without this project. The only claim we make is that we are doing our
best to achieve this goal. [2]
Another big advance related to the problem of direct neural interfacing came
about fairly recently but I cannot remember my source. If anyone knows of
the research I'm describing in the following sentences, please email me! If
not, I'm sure I can dig up the references given a little time. So, for those
of you who don't do this automatically for missing references, please *take-
what-i-say-with-a-grain-of-salt*, because this is strictly from memory.
Anyway, the work has to do with the fact that cells of the CNS aren't happy
regenerating (one of the reasons spinal cord injuries are so traumatic).
The reason CNS cells don't regenerate has apparently been either discovered
or more precisely defined: it's not that they don't regenerate, it's that
the body secretes a growth-suppression factor which keeps them from regen-
erating. A research group has found an anti growth-suppression factor which
either suppresses or negates the effects of the natural factor; they have
reported regeneration success in an experiment where they severed the spinal
cord of a rat to which the anti growth-suppression factor was administered.
I want to say the experiment involved actually _removing_ a small (>1mm or
less) section of nerve so that the ends weren't touching, but I'm not really
sure about that.
The stuff above, in conjunction with the Stanford experiments, is tremendously
exciting, at least for me. Of course, there exist complicating questions and
problems beyond those associated with simply "tapping into" a single neuron.
Is that really what should be done? A big problem there is the fact that
science has yet to really make a dent in the neural connectivity problem.
It's one thing to have action potential information for every single axon in
a bundle, but it's an entirely different thing to assimilate that information
into something meaningful. Much more often in research it's population
potentials (intercellular potentials resulting from the combined microcurrents
through a small population of neurons) which are correlated to events in
the physical world. Then again, the field of neural networks (in the silicon
context, not the biological :-) might likely hold a solution to the inter-
pretation problem.
I fancy the applications to VR interfaces, if (*when*!) that time comes, will
appear long after rehabilitative applications are perfected, but progress is
after all progress!
-marcus-
ps: quotes taken without permission from issues of _Science_. I looked for
copyright restrictions in the magazine but found none relating to information
redistribution.
--------------------------
1. "Tapping into Nerve Conversations" (Research News), _Science_ 248,
p. 555 (4 May 1990). There's a good uphoto of the earlier
64-electrode prototype chip.
2. "Neural Interfacing" (Letters), _Science_ 248, pps. 1280-1281
(15 June 1990).
--
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