Researchers have for the first time shown that they can control the behavior of monkeys by using pulses of blue light to very specifically activate particular brain cells.
The findings represent a key advance for optogenetics, a state-of-the-art method for making causal connections between brain activity and behavior. Based on the discovery, the researchers said that similar light-based mind control could likely also be made to work in humans for therapeutic ends.
"We are the first to show that optogenetics can alter the behaviors of monkeys. This opens the door to use of optogenetics at a large scale in primate research and to start developing optogenetic-based therapies for humans," said Wim Vanduffel of Massachusetts General Hospital and KU Leuven Medical School.
In optogenetics, neurons are made to respond to light through the insertion of light-sensitive genes derived from particular microbial organisms. Earlier studies had primarily validated this method for use in invertebrates and rodents, with only a few studies showing that optogenetics can alter activity in monkey brains on a fine scale.
In the new study, the researchers focused on neurons that control particular eye movements. Using optogenetics together with functional magnetic resonance imaging (fMRI), they showed that they could use light to activate these neurons, generating brain activity and subtle changes in eye-movement behavior.
The researchers also found that optogenetic stimulation of their focal brain region produced changes in the activity of specific neural networks located at some distance from the primary site of light activation.
The findings not only pave the way for a much more detailed understanding of how different parts of the brain control behavior, but they may also have important clinical applications in treating Parkinson's disease, addiction, depression, obsessive-compulsive disorder, and other neurological conditions.
The study has been reported online in Current Biology, a Cell Press publication.