Light from outside the brain can turn on nerve cells in monkey brains
An extra-sensitive molecule made nerve cells respond to dim light
![nerve cell illustration](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2019/10/102119_LS_optogenetics_feat.jpg?fit=1028%2C579&ssl=1)
With a new type of light-sensitive protein, blue light activated nerve cells deep within a monkey’s brain. Orange light stopped the extra activity.
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