Head, Division of Neurosurgery, St. Michael's HospitalDr. Macdonald's major research interests are in the field of aneurismal subarachnoid hemorrhage and cerebral vasospasm. We are investigating causes of delayed neurological deterioration after subarachnoid hemorrhage using animal models and testing hippocampal electrophysiology and function, animal behavior, learning and memory and changes in gene expression and function. We also are studying mechanisms of large artery vasospasm after aneurismal subarachnoid hemorrhage and effects of intracerebral and subdural hemorrhage on the brain. All of this work is laboratory-based as well as clinical with clinical trials and patient-based studies conducted testing similar hypotheses.