MEDFORD/SOMERVILLE, Mass. (February 27, 2013) For the first time, scientists have shown that transplanted eyes located far outside the head in a vertebrate animal model can confer vision without a direct neural connection to the brain.
Biologists at Tufts University School of Arts and Sciences used a frog model to shed new light literally on one of the major questions in regenerative medicine, bioengineering, and sensory augmentation research.
"One of the big challenges is to understand how the brain and body adapt to large changes in organization," says Douglas J. Blackiston, Ph.D., first author of the paper "Ectopic Eyes Outside the Head in Xenopus Tadpoles Provide Sensory Data For Light-Mediated Learning," in the February 27 issue of the Journal of Experimental Biology. "Here, our research reveals the brain's remarkable ability, or plasticity, to process visual data coming from misplaced eyes, even when they are located far from the head."
Blackiston is a post-doctoral associate in the laboratory of co-author Michael Levin, Ph.D., professor of biology and director of the Center for Regenerative and Developmental Biology at Tufts University.
Levin notes, "A primary goal in medicine is to one day be able to restore the function of damaged or missing sensory structures through the use of biological or artificial replacement components. There are many implications of this study, but the primary one from a medical standpoint is that we may not need to make specific connections to the brain when treating sensory disorders such as blindness."
In this experiment, the team surgically removed donor embryo eye primordia, marked with fluorescent proteins, and grafted them into the posterior region of recipient embryos. This induced the growth of ectopic eyes. The recipients' natural eyes were removed, leaving only the ectopic eyes.
Fluorescence microscopy revealed various innervation patterns but no
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