By The Huffington Post News Editors

By: Charles Choi, LiveScience Contributor
Published: 02/27/2013 06:06 PM EST on LiveScience

Eyes hooked up to the tail can help blinded tadpoles see, researchers say.

These findings could help guide therapies involving natural or artificial implants, scientists added.

A major roadblock when it comes to treating blindness and other sensory disorders is how much remains unknown about the nervous system and its ability to adapt to change. To learn more about the relationship between the body and the brain, researchers wanted to see how capable the brain was of interpreting sensory data from abnormal “ectopic” locations from which it normally does not receive  signals.

Eye on the tail

Scientists experimented with 134 tadpoles of the African clawed frog Xenopus laevis, a common lab animal. They painstakingly grafted new eyes onto places such as their torsos and tails and then surgically removed their original eyes. [See Images of the Odd-Eyed Tadpoles]

“We do a lot of work to understand regenerative biology, and that entails experiments that change the body,” researcher Michael Levin, a developmental biologist at Tufts University, told LiveScience. “We have four-headed worms, six-legged frogs, and many other unusual creatures here as part of our work on bioelectricity and organ regeneration.”

These experimental tadpoles then received a vision test the researchers first refined on normal tadpoles. The tadpoles were placed in a circular arena half illuminated with red light and half with blue light, with software regularly switching what color light the areas received. When tadpoles entered places lit by red light, they received a tiny electric zap. A motion-tracking camera kept tabs on where the tadpoles were.

Remarkably, the scientists found that six tadpoles that had eyes implanted in their tails could apparently see, choosing to remain in the safer blue-light areas.

“The brain is not wired to find an eye on the tail, since it’s never happened before and thus is not something the brain has evolved specifically to deal with, and yet it can recognize this patch of tissue as providing valuable visual information,” Levin said.

“These findings suggest that the brain has remarkable plasticity and may actually take a survey of its body configuration to make use of different body arrangements,” Levin added. “If it were not the case, then every time a mutation produced an improvement in body plan — a large significant change in anatomy — the animal would die and the beneficial mutation would be lost.”

Rather, when a mutation makes a change in the body plan of an embryo, the brain-body programs that tell an eye to see and a hand to grasp, for instance, “don’t suddenly become useless,” Levin said. “The brain can map its activity onto a wide range of configurations of the body. This modularity makes it much easier for complex new body features to evolve.”

Augmentation technology

The transplanted eyes came from tadpole donors genetically modified to generate …read more
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