A team lead by neurobiologist Richard H. Kramer, UC Berkeley professor of molecular and cell biology, and Dirk Trauner, assistant professor of chemistry, inserted a light-activated switch into brain cells normally insensitive to light, enabling the researchers to turn the cells on with green light and turn them off with ultraviolet light.
This trick could potentially help those who have lost the light-sensitive rods and cones in their eyes because of nerve damage or diseases such as retinitis pigmentosa or age-related macular degeneration. In these cases, the photoreceptor cells are dead, but other nerve cells downstream of the photoreceptors are still alive. In particular, retinal ganglion cells, which are the third cell in the path from photoreceptor to brain, could take over some of the functions of the photoreceptors if they could be genetically engineered to respond to light.
Kramer envisions a device, reminiscent of the eyepiece worn by the blind Geordi La Forge in "Star Trek The Next Generation," that would provide some semblance of the real world.
"We may be able to use laser scanning to trace on and off patterns on the retina and allow people to see visual patterns," Kramer said. "Sometimes I'm not sure where the science ends and the fantasy begins, but I think we can make it work."
"With this technique, you also could confer light sensitivity on organisms that normally don't have vision, such as the nematode worm C. elegans," Trauner said. "Taking this from a chemical novelty to showing that it works in a biological system is a real breakthrough."
Kramer, Trauner and their colleagues will report their results on Nov. 21 in a paper published online in the journal Nature Neurosci
Contact: Robert Sanders
University of California - Berkeley