About the Authors
Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
The authors have declared that no competing interests exist.
The author(s) have made the following declarations about their contributions: Conceived and designed the experiments: YFM MAL JA VB MRF. Performed the experiments: YFM MAL JA BA. Analyzed the data: YFM MAL JA VB MRF. Contributed reagents/materials/analysis tools: YFM MAL JA BA VB MRF. Wrote the paper: YFM MAL JA VB MRF.