1. Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC 27705, USA.
2. Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
3. Department of Radiology, Center for In Vivo Microscopy, Duke University, Durham, NC 27705, USA.
4. Bio-medical Machine Shop, Pratt School of Engineering, Duke University, Durham, NC 27705, USA.
5. Department of Pathology, School of Medicine, Duke University, Durham, NC 27705, USA.
6. Department of Biology, Emory University, Atlanta, GA 30332, USA.