Qionger He1, Erica D Arroyo2, Samuel N Smukowski3, Jian Xu, Claire Piochon1, Jeffrey N Savas3, Carlos Portera-Cailliau2 and Anis Contractor1,4* 1Department of Physiology & 3Department of Neurology, Northwestern University Feinberg School of Medicine; 2Departments of Neurology and Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 & 4Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Chicago, IL 60611