[1] Univ Western Ontario, Elbom Coll, Sch Commun Sci & Disorders, London, ON N6G 1H1, Canada
[2] York Univ, Dept Languages Literatures & Linguist, Toronto, ON M3J 2R7, Canada
[3] Univ Toronto, Hosp Sick Children, Autism Res Unit, Toronto, ON M5G 1X8, Canada
[4] Univ Toronto, Dept Paediat, Toronto, ON M5S 1A1, Canada
[5] Childrens Hosp Philadelphia, Dept Radiol, Philadelphia, PA 19104 USA
[6] Univ Penn, Sch Med, Philadelphia, PA 19104 USA