As you know, this is not the way vision is supposed to work--your eyeballs are supposed to be connected to a big fat nerve that carries incoming signals back to your brain, which combines the information from both your eyes into a 3D picture of the world in front of you. Without that direct link to the brain, your eyeballs are useless.
At least, that's the way scientists have thought about it for the last several centuries. But over the past few decades, experiments in animals and humans have repeatedly shown that the central nervous system--including the brain and spinal cord--is a lot more flexible and adaptable than people used to think it was. If one part of the brain gets damaged, for instance, the information that used to flow to the damaged sector is often re-routed, and another part of the brain takes on the job of processing it.
So these newer findings got the Tufts University researchers wondering: could the optic nerve really be the only route for incoming visual signals? And could a different part of the nervous system, like the nerves further down the spinal cord, process those signals on their own, without help from the brain?
Tadpoles, they realized, would be a good way to test this question: they would perform surgery at a time when the tadpoles were still developing, so that the transplanted eyes would have time to put down nerve roots that could potentially hook up to the rest of the tadpoles' nervous systems.
The surgeries were painstaking, but the researchers were able to successfully graft eyeballs onto the tails of over 200 tadpole embryos:
As you know, this is not the way vision is supposed to work--your eyeballs are supposed to be connected to a big fat nerve that carries incoming signals back to your brain, which combines the information from both your eyes into a 3D picture of the world in front of you. Without that direct link to the brain, your eyeballs are useless.At least, that's the way scientists have thought about it for the last several centuries. But over the past few decades, experiments in animals and humans have repeatedly shown that the central nervous system--including the brain and spinal cord--is a lot more flexible and adaptable than people used to think it was. If one part of the brain gets damaged, for instance, the information that used to flow to the damaged sector is often re-routed, and another part of the brain takes on the job of processing it.So these newer findings got the Tufts University researchers wondering: could the optic nerve really be the only route for incoming visual signals? And could a different part of the nervous system, like the nerves further down the spinal cord, process those signals on their own, without help from the brain?Tadpoles, they realized, would be a good way to test this question: they would perform surgery at a time when the tadpoles were still developing, so that the transplanted eyes would have time to put down nerve roots that could potentially hook up to the rest of the tadpoles' nervous systems.The surgeries were painstaking, but the researchers were able to successfully graft eyeballs onto the tails of over 200 tadpole embryos:
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