An eye transplanted to a tadpole’s tail is capable of detecting and interpreting visual
information, even if not connected directly to the brain.
The latest addition to the strange menagerie of engineered animals is a group of blind tadpoles that see out their tails. The findings, published in the Journal of Experimental Biology in February, provide further proof of the nervous system’s remarkable capacity to rewire itself.
Researchers painstakingly transplanted eyes from donor tadpoles onto the torso and tails of animals that had had their own eyes surgically removed. About 20 percent of the engineered animals showed they could actually use those eyes, even when they weren’t directly connected to the brain. The animals swam away from red light, which they had previously been taught was associated with an unpleasant zap of electricity.
For the eyes to work, they did have to connect to the animal’s spinal cord. But they didn’t need to integrate into the sophisticated machinery that makes up the visual system.
Researchers say the ability to bypass the brain has implications for tissue engineering and efforts to treat blindness and other sensory disorders because they suggest new therapies may not need to involve the brain circuits typically involved in vision. That could prove especially helpful for people who have damage to crucial parts of the eye or brain.