1. School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
2. Division of Neurology, National University Hospital, Singapore 119074, Singapore
3. Department of Neurology, Medical University of South Carolina, Charleston, SC 29425, USA
4. Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
5. Harvard Medical School, Boston, MA 02115, USA