Finally, it was time to put the cyclops to the test. Using an underwater arena rigged with blue and red LEDs and electric shock, scientists ran through an exhaustive array of controls and variables. Interestingly, the tadpoles with no eyes at all could still react to LED changes, revealing that they may have other ways of sensing light. However, they proved woefully inadequate at avoiding shock, showing whatever information they were getting was ultimately flawed or unusable. On the other end of the spectrum were the control tadpoles that quickly learned to avoid the shocks through the scientists' regimen of aversive conditioning.
As for the main event? Amazingly, a statistically significant portion of the transplanted one-eyes could not only detect LED changes, but they showed learning behavior when confronted with electric shock. Though eyes have been placed on or near rat brains in previous studies with success, this marked the first time a vertebrate eye has been able to send visual information to the brain without a direct connection — and from as far away as the other end of the organism.
Obviously, enormous questions remain. For instance, how does the brain know information coming up the spine from the tail is visual? It should have no idea what that knobby bit of posterior flesh is blinking about — and yet it seems to take the information in stride. The paper suggests perhaps different types of data are somehow marked, not altogether different from the way we demarcate files and commands in a computer.
Ahead lies everything from better computer brain interfaces to bioengineered organ systems. If we can understand the limits of the brain's plasticity (the ability to change and adapt from experience), we might be able to one day create cybernetic devices that don't just do what we program, but discover on their own what is required.
On the other hand, we do seem to be getting dangerously close to creating the eyeball-y beast from "Pan's Labrynth."
Jason Bittel serves up science for picky eaters on his website, BittelMeThis.com. He lives in Pittsburgh.