1. Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117600
2. Department of Biology, San Diego State University, San Diego, California 92182, United States
3. Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119260
4. Neurobiology and Ageing Research Programme, Life Sciences Institute, National University of Singapore, Singapore 119260