Medical College of Wisconsin professor of cell biology Jay Neitz and his wife Maureen Neitz have been working with a species of monkey whose males have only two kinds of cones. The Neitzes have created a virus containing a gene for a photopigment that the monkeys do not have (L-opsin), and have injected this virus into the eyes of two adult monkeys. Some of the cones absorbed the viral DNA and after five months the monkeys became receptive to light of different wavelengths. The adaptation is believed due to perceptual adaptation rather than any physical changes within the brain. “That’s the way we were thinking about neural plasticity before,” Neitz said. Instead, the monkeys are apparently “learning how to use the same old circuits in a new way when the information coming over the lines changed.”[12] If the monkeys remain free of any side effects, this might be tested on colorblind humans to give them full color vision. If that proves successful, the Neitzes hypothesize, it might be possible to give people with normal sight a fourth cone, equipping human beings with “tetrachromatic” vision.
