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.