1. Ryan White Center for Pediatric Infectious Disease and Global Health, Indiana University School of Medicine, Indianapolis, Indiana;
2. Departments of Pediatrics and
3. Department of Epidemiology, University of Maryland School of Medicine, Baltimore, Maryland;
4. RTI International, Research Triangle Park, North Carolina;
5. Laboratories of Cognitive Neuroscience, Boston Children's Hospital, Boston, Massachusetts;
6. Department of Pediatrics, Harvard Medical School, Boston, Massachusetts; and
7. Department of Human Development, Harvard Graduate School of Education, Cambridge, Massachusetts