Researchers at MIT have overcome a key hurdle in optogeneticsÂ by creating a new photosensitiveÂ protein that responds to a light source outside the brain. The latest findings, announced by the McGovern Institute for Brain Research and published in the journalÂ Nature Neuroscience, would allow the use of optogenetics in long-term studies without the need for implanting a light source, the researchers said.
Current opsins used in optogenetics respond best to blue and green lights, but the newly engineered protein, Jaws, responds to red light.
Ed Boyden’s team at MIT turned to bacteriaÂ Haloarcula marismortui and Haloarcula vallismortis, whereÂ they had previously identifiedÂ red-light sensitive opsins, but found their photocurrent insufficient. Graduate student Amy Chuong and the team tested the electrical propertiesÂ of various mutations of the protein until they found one that was just as responsive to red light and strong enough to switch off neural activity.
The new opsin allowed the researchers to turn off neuronal activities as deep as 3 mm in the brain, according to theÂ McGovern Institute.
In addition to using optogenetics for long-term studies, where invasive optogenetic light sources are undesirable, the new findings could help researchers inhibit a larger area of the brain in larger animals.
Researchers atÂ Friedrich Miescher Institute for Biomedical Research in Switzerland, who have already tested Jaws in the mouse retina, found that it could also be useful in treating a degenerative disease of the cone cells known as retinitis pigmentosa.
(Sources: McGovern Institute for Brain Research at MIT)