1. Department of Neurosurgery, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
2. Division of Anatomy, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
3. Division of Biomedical Communications, Department of Surgery, University of Toronto, Ontario, Canada
4. Division of Neurosurgery, St. Michael's Hospital, Departments of Neurosurgery, Education, and Public Health, University of Toronto, Toronto, Ontario, Canada