About the Authors
Laboratory for Neuroengineering, Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: ZC. Performed the experiments: ZC. Analyzed the data: ZC. Contributed reagents/materials/analysis tools: ZC. Wrote the paper: ZC DB SP.