"GABA communication clearly conveys information about what brain cells experience of the outside world, and, in this case, keeps the brain stem cells in reserve, so if we don't need them, we don't use them up," says Song.

Other authors on the paper include Juan Song, Chun Zhong, Michael Bonaguidi, Gerald Sun, Derek Hsu, Kimberly Christian and Guo-li Ming of Johns Hopkins University, Yan Gu and Shaoyu Ge of State University of New York at Stony Brook, Konstantinos Meletis of the Karolinska Institutet, Z. Josh Huang and Grigori Enikolopov of the Cold Spring Harbor Laboratory, Karl Deisseroth of Stanford University and Bernhard Luscher of Pennsylvania State University.

This work was supported by grants from the National Institute of Neurological Disorders and Stroke (NS047344, NS048271), the National Institute of Child Health and Human Development (HD069184), National Institute of Mental Health (MH089111), the National Institute on Aging (AG040209), the National Alliance for Research on Schizophrenia and Depression, the Adelson Medical Research Foundation, the New York State Stem Cell Science, the Ellison Medical Foundation, the Life Sciences Research Foundation and the Maryland Stem Cell Research Fund.