1. Department of Neurology, Myongji Hospital, Hanyang University College of Medicine, Goyang, Korea.
2. Department of Neurology, Seoul National University Hospital, Seoul, Korea.
3. Department of Neurology, Center for Hospital Medicine, Seoul National University Hospital, Seoul, Korea.
4. Peabody College of Education and Human Development, Vanderbilt University, Nashville, TN, USA.
5. Doo Neurology Clinic, Cheonan, Korea.
6. Department of Neurology, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
7. Department of Neurology, Incheon Sejong Hospital, Incheon, Korea.
8. Euan MacDonald Centre for Motor Neurone Disease Research, Human Cognitive Neuroscience, School of Philosophy, Psychology and Language Science, University of Edinburgh, Edinburgh, UK.
9. Department of Neurology, Seoul National University College of Medicine, Neuroscience Research Institute, Seoul National University Medical Research Council, Seoul Metropolitan Government Boramae Medical Center, Seoul, Korea.