A PAIN supplement commemorating the 50th anniversary of the International Association for the Study of Pain.

aDivision of Brain, Imaging, and Behaviour, Krembil Brain Institute, University Health Network, Toronto, ON, Canada bDepartment of Surgery, University of Toronto, Toronto, ON, Canada cInstitute of Medical Science, University of Toronto, Toronto, ON, Canada dUniversity of Toronto Centre for the Study of Pain, Toronto, ON, Canada eFaculty of Dentistry, University of Toronto, Toronto, ON, Canada fDepartment of Physiology, Faculty of Medicine, Toronto, ON, Canada *Corresponding author. Address: Krembil Brain Institute, Krembil Research Institute, University Health Network, Toronto Western Hospital, 399 Bathurst St, Room MP12-306, Toronto, ON M5T 2S8, Canada. Tel.: (416) 603-5662. E-mail address: [email protected] (K. D. Davis).