Scientists Control Monkeys’ Brains with Light

For the first time, scientists have been able to affect the behavior of a primate using optogenetics—a technique by which genetically modified neurons are made to fire with light.

The study, published today in the journal Current Biology, sets the stage for using this powerful new tool to study how the brain enables complex primate cognition and, more distantly, for using the technique to treat disease.

To control the electrical firing of a neuron, scientists use a virus to deliver a gene into brain cells. The gene is designed to produce a light-responsive protein (see “Brain Control“).

Depending on the type of light-sensitive protein used, this genetic modification will either activate or silence a neuron in response to a specific color of light, delivered via optical fibers inserted into the brain.The seven-year-old field of optogenetics has given neuroscientists a more precise tool to examine the connections between the groups of neurons that set up neuronal circuits.

These brain circuits control behaviors such as movement and emotion and, when faulty, can lead to diseases ranging from depression to Parkinson’s.

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