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Severed Optical Nerves Can Be Made To Grow Again
Anonymous Coward writes: "It is being hailed as one of the most significant advances in nerve regeneration in a decade. After severing an optic nerve in rats, neurologists have found a way to reconnect it to the brain so that it once again transmits normal electrical signals. As reported in the New Scientist this achievement is a first in mammals, and may hint at ways of reversing some types of blindness in people. Scientists also hope to use a version of the technique to treat people with spinal cord injuries.
The team is currently studying the rats' behaviour to assess how good their eyesight is.
While the rat team is currently trying to figure out how to anaesthetize a large group of humans, and then gnaw their eyes out.
I once heard Oliver Sacks talk about somebody who had been blind their whole life (due to completely opaque cataracts, I believe). A new surgery technique restored the fellow's sight. But when he woke up from surgery, all he could see was an overwhelming mass of incomprehensible color. He couldn't distinguish faces, object, or even simple shapes.
His eyes, it turned out, were functioning perfectly. But because he has been blind during infancy, the visual parts of his brain had never developed -- he had never learned to see.
He did slowly learn, but it was agonizing for him. His newfound sight was overwhelming and sent his brain into chaos. After a long time, with tremendous effort, he could shave for a minute or two in front of the mirror -- but it was absolutely exhausting, and had to finish with the lights off.
Eventually, an unrelated optical infection threatened to take his sight, and he chose to let it run its course. Returning to blindness was a tremendous relief.
Perhaps slightly off-topic, but fascinating!
If anyone has any interest in how the brain works and the insights one can gain by looking at what happens when the brain malfunctions, I can't recommend the Oliver Sacks books highly enough. He's a neurologist who studies the brain and has a positive gift for writing about his subjects. Not to be touchy-feely, but he writes about them in a very sensitive way to where you don't feel like people are getting "exploited" for his own gain.
Other tales in his books to whet your appetite:
1) "The man who mistook his wife for a hat", which is the title of one of his books about a man who, otherwise normal, had problems with misconnecting objects to their identities,
2) A woman who could perceive things only on one side (say the left), but not on the other, even though her vision was perfect. When she ate, she would have to eat one side, then turn the plate, eat another half, etc. She was perfectly sane, but just had this wierd perceptual problem.
3) The man who could not make new memories, and lived the same moments over and over. He could remember everything up to an accident he had, but nothing further. Every day he would re-meet the same people. They have to keep mirrors away from him because it freaks him out because he looks too old for himself.
4) The "anthropologist" on mars, who is a pretty famous autistic teacher I think at Colorado. She has perfect image recall, but is entirely without emotions. She actually has her own book that she wrote about what it's like to be her, but I can't remember the name of it (anyone?).
The books are absolutely chock-full of stories like this. If this stuff fascinates you like it does me, I give these books my absolute highest recommendation.
Sometimes it's best to just let stupid people be stupid.
One thing I have to wonder about is if the nerves grow up the 'wrong' pathway, and how long it will take the brain to sort it out.
When I was 15 years old, I put my hand through an old glass door while trying to open it. The glass sliced through my right wrist, severing pretty much everything (apart from about half of one tendon). I probably don't have to mention the large quantities of blood that went everywhere.
Six hours of microsurgery, and it was put back together again...followed by three months of three hours a day physiotherapy.
The thing I found fascinating was that when the median nerve [0] (the nerve that runs up the middle of your wrist and supplies your index finger to thumb and half your palm) is that some of the nerves went the wrong way. I could stroke part of one finger, and the sensation would come out somewhere else - like a different finger, or a different side of the finger. It was...well...very weird.
However, it didn't take long for the brain to fix it. After a short while, the brain learned the error, and sensations came out in the expected place.
It's one thing when this happens to fingers - but I wonder if you'd need some kind of "optotherapy" to coach the brain to fix the image problems you'd get with optical connections wired differently to how they were before.
[0] Movement of the fingers is controlled by the muscles in the forearm. The median nerve does sensation.
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