Structure of the Optical Nerves ??

Hannah Dvorak hdvorak at cns.caltech.edu
Tue Sep 5 18:07:57 EST 1995


In article <DEDsr0.BH6.0.queen at torfree.net>, bq705 at torfree.net (Raymond P. Young) says:
>
>My guess is that it is still not possible, yet.  Experiments were started 
>in this area a number of years ago, but there have been problems 
>(ethical, technical, potential repercussions of making a surgical 
>error with a patient).  I would be surprised if this sees 
>fruition before 2000, and whether it is marketable after that.  
>This is my bet, though I may be a bit out of step.
>
>R.P.Young, Ph.D.
>
There is a group in Boston (afraid I can't remember the names, or even
who they're affiliated with - I think it *might* have been M.I.T. and
the Mass. General Hospital) who are working on this problem.  Their
goal is to make implants to put over the retina to directly stimulate
retinal ganglion cells in cases when the photoreceptors are destroyed
dut to damage or disease.  The implant receives input from a camera
that would be mounted on glasses.  Power to the implant is provided by
an infrared beam, I believe.  When one of them spoke here at Caltech a 
year or so ago, they were at the stage where they were trying to 
surgically insert these implants into the eyes of rabbits, and they
were having real problems just having the things stay put.  Looks like
it'll be a long time before they have something practical.

The only other thing I've seen along these lines was a case where a
blind woman had electrodes implanted directly into her visual cortex,
and stimulation of these electrodes could cause her to "see" spots of
various sizes and colours.  The idea was to try to at least be able
to spell out letters in a dot-matrix fashion.

>
>kaim at pi.net wrote:
>
[snip]

>: What I'd like to know is how do the optic nerve cells pick up signals, and 
>: how do "bio sensors" in genaral work. 

I would recommend you pick up the textbook "From Neuron to Brain" by
Nicholls, Martin and Wallace for a good introduction to the nervous
system and vision in particular. 
>
>: Like touch and heat/cold sensations.
>
>: I know it is a electrical/chemical process that starts somewhere.
>
>: Fill me in.
>
>
>: Ronald Kaim.
>

Hope this helps.

- Hannah Dvorak



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