1. Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
2. Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, USA
3. Department of Biochemistry and Molecular Pharmacology, Worcester, MA, USA
4. Mass Spectrometry Facility, University of Massachusetts Medical School, Shrewsbury, MA, USA
5. Department of Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands
6. The Ken & Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
7. Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
8. Howard Hughes Medical Institute, Chevy Chase, MD, USA