[1] Univ Toronto, Dept Physiol, Toronto, ON, Canada
[2] Univ Hlth Network, Div Neuroradiol, Joint Dept Med Imaging, Toronto, ON, Canada
[3] Univ Toronto, Dept Med Imaging, Toronto, ON, Canada
[4] Univ Toronto, Inst Med Sci, Toronto, ON, Canada
[5] Univ Hlth Network, Dept Anesthesiol, Toronto, ON, Canada
[6] Sunnybrook Hlth Sci Ctr, LC Campbell Cognit Neurol Res Unit, Toronto, ON, Canada