1. Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.
2. Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06510, USA.
3. Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
4. Department of Ophthalmology, Yale University School of Medicine, New Haven, CT 06510, USA.