About the Authors
Department of Anatomy & Neurobiology, Washington University Medical School, St. Louis, Missouri, 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: LBD PHT. Performed the experiments: LBD. Analyzed the data: LBD. Contributed reagents/materials/analysis tools: LBD. Wrote the paper: LBD PHT.