From: Ramez Naam (ramezn@Exchange.Microsoft.com)
Date: Thu Jan 27 2000 - 23:59:54 MST
A mention of this in _Slate_ caught my eye.
A Dr. William Dobelle has apparently been implanting patients with
electrodes to stimulate their visual cortex for the last 20 years. In just
the last year Moore's law has brought the electronic (and external)
components of his system up to feasible performance and down to a feasible
size.
The system uses a meager 64 electrodes implanted inside the brain. In the
volunteer discussed in the published paper, visual acuity of 20/1200 was
reached with a small portable camera able to fit over one eye. The paper
indicates that the camera itself is a bottleneck in visual acuity, due to
the optical limitations of such a small size. Digital zoom in a recent
upgrade to the system has brought visual acuity up to 20/400, though this is
at the cost of temporary tunnel vision.
In addition to the camera, the system can take direct input from a
television or computer video output. Giving the patient net access via this
mechanism is explicitly discussed.
Dobelle has plans for a newer version of the system, later this year, that
will have 256 electrodes per hemisphere, for a total of 512. The paper also
talks about the possibility of upping this number by implanting electrodes
which stimulate the visual association cortex. (The current target is the
primary visual cortex, though it appears some leakage is occurring.)
The amazing thing to me, beyond the incredible potential for this, is that
the implant in the volunteer discussed in the paper has been in place for 20
years. Only the external components of the system have been upgraded in
that time. Also, Dobelle claims to have implanted neurostimulators in
more than 15,000 patients worldwide. I had no idea this was going on.
The paper is at http://www.dobelle.com/vision/asaio1.html
mez
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