Scientists are currently able to make neurons and other brain cells from stem cells, but getting these neurons to properly function when transplanted to the host has proven to be more difficult. Now, researchers at Sanford-Burnham Medical Research Institute (Sanford-Burnham), in collaboration with researchers at Stanford University, have found that with the use of optogenetics, these stem cell-derived neurons could not only conduct electrical impulses, but also rouse neighboring neuronal networks into firing—at roughly the same rate they would in a normal, functioning hippocampus. The study was published in the November 7 issue of the Journal of Neuroscience.

"We showed for the first time that embryonic stem cells that we've programmed to become neurons can integrate into existing brain circuits and fire patterns of electrical activity that are critical for consciousness and neural network activity," said Stuart A. Lipton, M.D., Ph.D., senior author of the study. Lipton is director of Sanford-Burnham's Del E. Webb Neuroscience, Aging, and Stem Cell Research Center and a clinical neurologist.

The trick turned out to be light. Lipton and his team—including Juan Piña-Crespo, Ph.D., Maria Talantova, Ph.D., and other colleagues at Sanford-Burnham and Stanford University—transplanted human stem cell-derived neurons into a rodent hippocampus, the brain's information-processing center. Then they specifically activated the transplanted neurons with Optogenetic stimulation, a relatively new technique that combines light and genetics to precisely control cellular behavior in living tissues or animals.

Optogenetics was developed by Scientific Council Member Karl Deisseroth, M.D., Ph.D., with the support of a NARSAD Young Investigator Grant in 2005. The new technology uses light to make neurons fire one at a time, giving researchers extraordinary control over specific brain circuits in living animals. Now in use at over 1,000 laboratories, the new method is enabling identification of the mechanisms that give rise to depression, anxiety, PTSD and other brain and behavior disorders.

Read more about this new study involving optogenetics