Researchers at MIT have overcome the current challenges in optogenetics by creating a new opsin that responds to red light from outside the skull.)
(Courtesy Jose-Louis Olivares/MIT/McGovern Institute for Brain Research)

Researchers at MIT have overcome a key hurdle in optogenetics by creating a new photosensitive 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 journal 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 bacteria Haloarcula marismortui and Haloarcula vallismortis, where they had previously identified red-light sensitive opsins, but found their photocurrent insufficient. Graduate student Amy Chuong and the team tested the electrical properties 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 the 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 at 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)