D. James Surmeier, PhD, is the Nathan Smith Davis Professor and chair of the department of neuroscience at the Feinberg School of Medicine at Northwestern University. He studied mathematics as an undergraduate at the University of Idaho and received his PhD in physiology and biophysics from the University of Washington. He pioneered the use of advanced electrophysiological, optical and molecular approaches to unravel the roles of dopamine and acetylcholine in modulating the neuronal circuitry implicated in Parkinson’s disease (PD). These studies have yielded fundamental insights into how neural circuits adapt to the disease and how they contribute to side effects of symptomatic treatment. In addition, Dr. Surmeier’s group has made a significant contribution to our understanding of how the physiology of dopamine neurons leads to the mitochondrial oxidant stress implicated in PD pathogenesis. These studies have served as a foundation for large-scale clinical trials aimed at slowing PD progression.