From: sobiloff@acc.stolaf.edu (Chrome Cboy)
Subject: Re: VR and the handicapped
Date: Sat, 3 Nov 90 21:45:14 GMT
Organization: St. Olaf College; Northfield, MN

In article <10438@milton.u.washington.edu> lishka@uwslh.slh.wisc.edu (a.k.a. 
 Chri) writes:
>sobiloff@acc.stolaf.edu (Chrome Cboy) writes:
>>In article <9961@milton.u.washington.edu> esdvt@esdvt.esd.sgi.com (ESD DVT)
>> writes:
>>>    Why wouldn't people who are visually handicapped just have the
>>> dead nerves or whatever was failing bypassed by hardware so they
>>>could "see"  I think that as stuff like socketing in prosthetics becomes more
>>>viable this sort of thing would be possible?  any flames/comments/support?
>
>>Something like this certainly would be nice for both visually handicapped
>>individuals and non-handicapped individuals. However, our current level of
>>technology, not to mention our very limited knowledge of higher-order visual
>>processing, currently prohibits anything like this.
>
>Well, "yes and no" to the above statement.  I saw a remarkable show a
>few years back that dealt with computers and handicapped people.
>Possibly the most amazing development that was presented was
>artificial vision.  It has been a while since I have seen this program
>(so I don't remember the name of it, or that many details), but I am
>nearly positive it was on PBS.

I saw this segment as well; I think it was a Nova special, if I recall
correctly. The segment hightlighted the work being done by William Dobelle,
a summary of who's work is included at the end of this post. The military
was also doing basic research along these lines in the late 60's, early
70's, but with different goals in mind. (I think they were looking to
actually "jack in" a fighter pilot, bypassing controls such as the stick
and throttle.) Their stumbling block was that the areas in which the
electrode array were implanted would become physically damaged due to the
current being used, rendering the area unusuable after only a couple of
months.

>One final note: the "pain array" I referred to above is another form
>of artificial "vision." The system basically works the same way as the
>[...]
>forearm).  I am not sure how well these "pain arrays" work. 

They work remarkably well once the patient has become accustomed to the
system. The largest drawback has been trying to miniaturize the setup--
it is currently still a large chair that one must sit in. What with the
advances in materials science and the emerging ability to control
individual atoms in a manufacturing process I don't see why a practical,
mineaturized system won't be produced in a decade or so. (Assuming nothing
better comes along in the meantime, which is an admittedly large
assumption. :-)

Anyway, the article I mentioned previously:

[Taken from "Sensation and Perception", 3rd Ed., E. Bruce Goldstein,
Wadsworth, 1989, 50-51.]

William Dobelle and a team of researchers have developed plans for a visual
prosthesis: an artificial eye that can produce vision in the blind by
sending electrical signals to the visual cortex.  One proposed system, shown in
the figure on the left, consists of a subminiature television camera mounted
in a glass eye.  The TV camera picks up an image from the environment and
converts it into a pattern of electrical signals that is transmitted to a 
tiny computer mounted in a pair of dummy glasses.  After being processed by
the computer, these signals stimulate an array of electrodes placed on the
surface of the visual cortex, causing the person to see an image corresponding
to the original image received by the TV camera.

Although the system shown in the figure on the left does not yet exist, some
totally blind volunteers have had an array of 64 electrodes implanted on
their visual cortex.  A drawing of this array, based on an X-ray, is shown
on the right.  Wires from the electrodes pass through a small opening in the
skull, at the back of the head, and then wind beneath the scalp in an S-shaped
loop, before coming through the skin and terminating in a connector attached
to the skull with special bone screws.  Initial testing indicates that
stimulation of the cortex by a single electrode causes the observer to
perceive a phosphene--a small glowing spot of light that appears to be 
located at about arm's length.  Stimulation of a number of electrodes causes
a number of phosphenes to be seen as a pattern.  For example, Craig, a 35-
year-old government employee blinded 15 years earlier in an automobile
accident, was able to see letters, geometrical shapes, and simple pattern in
response to various patterns of stimulation of his electrode array.  When
a TV camera was connected to the system, Craig could also detect white
horizontal and vertical lines on a dark background.

These initial results are promising, although many problems must be solved 
before a visual prosthesis becomes available.  For example, phosphenes are
not always seen in the position corresponding to the position of the 
electrode on the cortex.  Adjacent electrodes may produce phosphenes that are
spaced far apart in the visual field, and adjacent phosphenes are sometimes
produced by widely spaced electrodes.  Additionally, some phosphenes are too
bright and obscure others, and phosphenes often flicker, even in response to
continuous electrical stimulation.  The next step is the development of a
512-electrode stimulation system that would transmit complicated information
rapidly enough so that the prosthesis could be used by a person as he or she
walks through the environment.  (Dobelle et al., 1974, 1976; Dobelle, 1977).



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                                                        ______________
_______________________________________________________/ Chrome C'Boy \________
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