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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.
It you can regenerate the optic nerve (or rather, prompt it to regenerate), what about other nerves? Spinal cord? Maybe you could make Rush Limbaugh hear again (or at least make him deaf only to the poor, human suffering and forward-thinking ideas like he was before).
Every year during my review, I just pray the words "slashdot.org" aren't mentioned.
... better that than listening to the KPMG theme song. Er, oops.
You could've hired me.
A very good friend of mine has a rare problem with the optic nerves in his eyes, which causes his vision to be so blurred that he is legally blind. All tests indicate that his eyes are shaped perfectly; he should have 20/20 vision. Furthermore, the doctors haven't been able to do much for him, since they dont' fully understand the problem. So they try to give him eye-glasses, and magnifiers, which don't do much good.
Research like this, when it might potentially spark a break-thru that could help someone close to you, is always great to see. I hope they make serious progress with this one.
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!
I thought the idea that it was immune system stimulating growth pretty interesting. The immune system releases a lot of signaling molecules at all stages. I'm not an immunologist per se, but I've never heard of any of them stimulating growth, but that certainly doesn't rule out the idea.
The article said that it was just inflammation that induced growth. I somehow doubt that, since everyone who's ever had irritated eyes has felt the fun of histamines and the primary immune response in action. If that sort of thing could make the blind see again, I'd be really surprised, even if it is on a larger scale.
If it is the immune system, I'd bet on cytokines released by helper T cells (those things that HIV targets) simply because these cells release a ton of stimulants. This may be triggered by the nonspecific inflammation like the author suggested, but I'd bet on the helper T as actually secreting growth signal.
If it is possible to use the immune system to regrow neurons, it's very likely applicable in other parts of the body too.
"I may not have morals, but I have standards."
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.
Well, we could repair your optic nerve miss, but it will involve crushing the lens of your eye. You'll be able to see again, but everything will look like it does in a circus mirror.
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Wrong. I happen to be one of those weird cases -- I've only been able to see out of my right eye since I was born. To me, this is a very exciting development. I've often hoped that it would one day be possible to restore sight in my left eye, and this looks like something that just might do it.
The people most interested in this article can't read it.
That may be true, but there are plenty here who (I'm sure) have full eyesight that seem find this to be an amazing advance.
"I turn away with fright and horror from the lamentable evil of functions which do not have derivatives."
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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My girlfriend introduced me to this guy, who everyone refers to as 'Jedi' at the local pool hall. He was your typical programmer-looking fellow with thick glasses. After we met, she told me about how he used to be fully blind from an accident and went to europe to get experimental surgery and is now able to see perfectly fine with the aid of glasses.
I know of quite a few stories about people in areas outside of the united states received advanced medical treatment; this is the first I actually know personally.
The really amazing thing about Jedi is that he could actually shoot a very good game of pool while blind. He would have his friend use a cue tapper and tap on the X/Y axis of the table to tell him where the object balls were at. I met him after he got his sight, but none-the-less an impressive feat.
I would recommend to anyone interested in alternate surgies than what america has to offer to check into the european medical field and you may be surprised. I wish I had more information about him, if anyone is interested in any further information post in my journal and I'll get a hold of him.
Dacels Jewelers can't be trusted.
Fischer D, Heiduschka P, Thanos S.
Lens-Injury-Stimulated Axonal Regeneration throughout the Optic Pathway of Adult Rats.
Exp Neurol. 2001 Dec;172(2):257-72. [PDF]
Apologies to those who are unable to view the pdf. (If you're not on a campus who subscribes to idea library, I don't think you can access it.)
Unfortuantly, these researchers still haven't purified the unknown factors that appear to be responsible for nerve growth. (They're in experimental opthamology... so it's not unexpected). Until these factors are purified and their functions described, nerve regrowth therapy will be difficult, if not impossible. Additionally, as some posters have pointed out, there are significant differences between rats and humans, and it remains to be seen if the same factors released by lens trauma are able to produce the same effects in humans or other model organisms. (But the posibility of non-applicability doesn't mean that rats and mice shouldn't be used, it just means that you need to test results obtained in them before applying them willy-nilly to other systems.)
http://www.donarmstrong.com
I hate to rain on several respective parades but optical nerves, albeit from rat embryos, could be made to do grow back about 11 years ago: I knew this because I worked with a research group at Guy's and Tommmy's in London who did this while deciding what I wanted to do at university.
The increased length is a bonus but not particularly important: They proved that the nerves formed synapses with the other nerves in the brain by shining light on the eye tissue and oberving the rats' pupils shrink in response.
Otherwise, the article is excellent.
Elgon
It'd be nice to see stereo again...
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There was a recent incident here in Australia where an accident victims fingers were transplanted from one hand onto the other...
One hand was severed during the accident, the other hand was crushed, they took the good fingers from the severed hand and put them on place of the crushed fingers. Wow.
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Close again... The retina is probably most accurately described as part of the brain. A strong argument for this description comes from looking at how the eye develops embryologicaly. Also, there are four layers of neurons in the retina, just as there are four layers of neurons in areas of brain cortex which are phylogenicaly old. (hence the term neocortex for cerebral cortex, which has six layers of neurons and is a recent evolutionary design.) The cell bodies of the neurons making up the optic nerve are in layer four of the retina and synapse with neurons in the thalamus, another phylogenicaly old brain structure. So, it is "brain all the way down."
So, should we call cranial nerve II (you wrote III, but you meant to say II) a "nerve?" or should we call it a "tract?"
Glad you asked. The real distinction is between central nervous system and periphrial nervous system. PNS neurons tend to heal, while CNS nerves do not. It is believed that this has much to do with the differences among the cells which provide support for the CNS vs PNS. For example, the myelin in PNS is provided by schwan cells, while the myelin in the CNS is provided by oligodendricytes, and there are many other differences in the "support staff" between CNS and PNS.
So, you ask, is CN II really a nerve or is it a tract? Well, if you look at it closely, it is realy part of the brain, and therfore properly called a tract, but the convention is to call it a nerve until it reaches the optic chiasma, then call it a nerve. But whatever you call it, it is very differant than the sort of nerve which gets cut when one, say, puts their hand through an old glass door.