Prior to taking his current position at the NINDS in 1993, Ronald D. McKay worked at the Massachusetts Institute of Technology (MIT). He also worked at Oxford University and at Cold Spring Harbor Laboratory. He received his doctorate for work in nucleic acid chemistry with Ed Southern, PhD, at the University of Edinburgh. In the first of his contributions to neurobiology, McKay showed that the nervous system was composed of many molecularly distinct neuronal types. This fact has now been supported by additional studies; at the time, however, these experiments had a strong impact because they were the first to use a powerful molecular technique to demonstrate the extraordinary biochemical complexity of the central nervous system (CNS). His recent work has focused on the stem cells of the CNS. In a 1988 paper he provided the first clear proof that neuronal precursors could be identified. These studies have generated a series of important insights into the properties of stem cells in the developing and adult nervous system. They challenge the textbook view that the differences between brain regions are irreversibly imprinted on cells at the time of gastrulation; instead, the results of his group add striking support to the conclusion that extracellular signals play a major role directing cell differentiation through the entire period of CNS development. McKay's work has importance beyond the intrinsic academic interest in the properties of stem cells and strongly influences strategies for cell- and gene-based therapies for CNS disease. He is a sought-after speaker and has been on the editorial boards of several major journals, including Neuron, Genes and Development, The Journal of Neuroscience, The European Journal of Neuroscience, Current Protocols in Neuroscience, Neurobiology of Disease, and Molecular and Cellular Neuroscience.