News : Bionic Eye

[TenaliRaman]

http://www.newscientisttech.com/article/dn11200?DCMP=Matt_Sparkes&nsref=bionic-eye

Title : Better 'bionic eye' offers new hope of restored vision

A tiny electronic pad is placed onto the retina of one eye, so that the electrodes are in direct contact with the ganglion cells. Each of the devices' 16 electrodes can stimulate 20 to 30 cells.

The user wears a pair of glasses that contain a miniature camera and that wirelessly transmits video to a cellphone-sized computer in the wearer's pocket. This computer processes the image information and wirelessly transmits it to a tiny electronic receiver implanted in the wearer's head.

The received in the implanted chip, the digital information is transformed into electrical impulses sent into the ganglion cells. From there, the brain takes over as the information travels down the optic nerve to the visual cortex at the back of the brain. The whole process occurs extremely rapidly, so that patients see in real-time. This is important any noticeable lag could stimulate the "vestibular-ocular reflex", making people feel dizzy and sick.

For the technique to work, the patient must still have some functioning ganglion cells - nerve cells that transmit visual information from the retinal cells to the optic nerve - as well as a fully-functioning optic nerve.

-- AI

 

[Q_Goest]

Hi Tenali, this is really fascinating. I located the research paper that discusses the experiment here: http://www.homepages.ucl.ac.uk/~smgxmdc/humayun.pdf [Broken]
Seems we're getting closer and closer to the brain in a vat scenario! lol

What's most interesting to me is that this and other research really emphasizes the location in the brain that's responsible for the phenomenon of visual experience*, the visual cortex, and that stimulation of those nerve inputs gives rise specifically to this phenomenon. To give rise to this phenomenon, it's as simple as stimulating those nerves.

It's interesting also that these nerves and that portion of the brain don't give rise to any other phenomenon, such as auditory experience, the sensation of taste, or any other phenomena. That may sound like an obvious observation that doesn't warrent stating, but what I find interesting is that even someone blind from birth has this location in their brain which is responsible only for the phenomenon of visual orientation (ie: how various shapes in a visual scene inter-relate) and visual experience.

There's an interesting article here regarding a brain scan on a person blind from birth.

ESREF ARMAGAN is a 52-year-old Turkish painter who has been blind in both eyes since the day he was born. He has never seen a coffee cup, a toothbrush, an elephant, or a tree-lined street, but he can draw them each, from any perspective, with or without shadows depending on the time of day. His portrait of President Clinton, which he painted from an embossed photograph, looks, well, like Clinton-complete with grey hair and bulbous nose-and though Armagan has never had an art lesson, the streets he paints stretch into the distance as converging parallel lines.

...

In July of 2004, at the Center for Noninvasive Brain Stimulation at Beth Israel Deaconess Hospital in Boston, Armagan agreed to have his brain imaged in a magnetic resonance imaging (MRI) machine while he drew with a pencil on a sheet of paper. He explored a set of objects by touch-a coffee cup, a toy elephant, a toothbrush-and then was told to imagine them and draw them all from memory. Each time, his drawings hit the mark.

''What we saw in the scan was quite amazing," says Dr. Alvaro Pascual-Leone, an associate professor of neurology at Harvard Medical School and director of the center. He and two colleagues in Beth Israel Deaconess's neurology department, Amir Amedi, PhD, and Dr. Lotfi Merabet, conducted a series of scans, each time challenging Armagan with more complex tasks. ''Esref's visual cortex lit up during the drawing tasks as if he were actually seeing," says Pascual-Leone. ''His scan, to the untrained eye, might look like the brain of a sighted person."

Ref: http://www.boston.com/news/globe/ideas/articles/2006/01/15/old_brain_new_tricks/?page=1

The article also mentions some tests done on subjects that could see perfectly well. The subjects were blindfolded and after a few days, these subjects seemed to exhibit the same phenomena as the blind subject - the portion of the brain responsible for visual experience was again being used...

Pascual-Leone's current work with his colleagues at Beth Israel Deaconess aims to answer those questions. For the past few years, they have been studying sighted subjects who volunteer to be blindfolded for five days and learn certain nonvisual tasks, including rudimentary Braille. In every case, before subjects donned the blindfold,functional MRI (fMRI) scans revealed little activity in their visual cortices during tactile tasks. After the subjects wore the blindfolds for two days, however, the scans showed bright patches of activity in the visual brain when the subjects used their fingers for tactile or Braille-reading tasks. By day five, the visual cortex glowed steadily during these same tasks. Yet two hours after the blindfolds were removed and the subjects' eyes had readjusted, scans of the visual area of their brains were as dark as they'd been on day one. Once the blindfolds were removed, touching, handling objects, and Braille-reading no longer activated ''sight" in the seeing.

Ref, page 3: http://www.boston.com/news/globe/ideas/articles/2006/01/15/old_brain_new_tricks/?page=3

So although it may seem obvious that stimulation of a given nerve will result in the proper subjective experince occurring, just as predicted by the brain in vat thought experiment, this kind of research really helps to bolster that conclusion, and show there are specific areas in the brain responsible for specific types of subjective experience. Furthermore, these areas of the brain seem to also be responsible for representing in the mind, how the world 'looks' or how locations of things in the world are oriented.

That said, I also noticed a neat article on a technology which might be seen as a competitor of visual implant technology you mentioned. It seems possible that information from other senses (auditory) could be used to feed information into the visual cortex. There's a website that explains it here:
http://www.seeingwithsound.com/retinal.htm

Basically, there are no implants. Instead, the visual field collected by the cameras is converted to noise which is supposed to give the wearer information about spatial locations.

The vOICe currently involves use of an external (extraocular) camera hidden unobtrusively inside for instance video sunglasses, but unlike the implant approaches it gets around the use of electrodes and surgery altogether, by mapping live camera images into sounds. It is then up to the blind user to learn to decode these generally extremely complex sounds as meaningful vision. Ideally, this would not only let the experienced blind user understand the visual view content, but also perceive it as truly visual, making it "feel" like vision. This would then make for a kind of artificial synesthesia, where sound input would be perceived as a visual view including light perception. It is not really known yet how far this can go, because the limited number of reports from users imply that the information on this is still anecdotal.

Ref: http://www.seeingwithsound.com/retinal.htm

I'll have to read a bit more to see what they're claiming exactly, but it seems as if it's saying the wearer of these special glasses will be able to percieve (visual orientation), not unlike how the surgical implant subject might percieve (visual experience). I guess what I'm saying is that it seems the visual cortex might be responsible for two phenomena we might entitle "visual orientation" and "visual experience". To actually produce visual experience, I wonder if the information doesn't necessarily have to come in from the visual nerves, whereas visual orientation does not produce the phenomenon of experience and instead only gives orientation of things in the visual field. Both phenomena use the visual cortex as the substrate, but they are different in how the phenomena is perceived by the mind.

Does that make sense, or does it thoroughly confuse the topic?

*Note: here, I'm using the term "experience" in the sense of a conscious phenomenon such as is used by Chalmers.