Optogenetics, the ability to use light to activate specific neurons in the brain, is continuing to prove itself as an amazing new technique to study and hopefully control different diseases and conditions. In a first, researchers from MIT used optogenetics to induce REM sleep in laboratory mice, an ability that may answer a lot of questions about how sleep works and how it can be controlled and improved.

In a study published in Proceedings of the National Academy of Sciences, the team showed how cholinergic neurons, thought to be related to sleep, actually can be used to trigger REM sleep. The team used a wired head mounted light source that penetrated the skull to deliver light directly into the brain. The mice themselves were genetically altered so that their neurons produce a light sensitive protein derived from algae. When neurons expressing this protein are illuminated, they activate and turning off the light brings them back to their previous state. The researchers showed that triggering cholinergic neurons within the pedunculopontine tegmentum (PPT) and laterodorsal tegmentum (LDT) regions of the brain can induce more frequent REM states. Interestingly, the length of REM sleep periods did not increase and remained about the same as during natural sleep.

Study in Proceedings of the National Academy of Sciences: Optogenetic activation of cholinergic neurons in the PPT or LDT induces REM sleep…

MIT: Using light to produce natural sleep patterns…

Link: Medgadget optogenetics flashbacks…