Because we lack a full understanding of how and why the brain responds to the reduced blood flow and low brain oxygen that occurs during a stroke, it is not known whether it is beneficial to treat the rise in blood pressure commonly seen in patients immediately following a stroke. We have developed cutting-edge technology permitting the direct, simultaneous measurements of the oxygen level at the site of a stroke, blood pressure, and the pressure inside the cranium. These measurements can be made over long time periods (weeks) in an experimental model. This will allow us to investigate how the brain responds to injury caused by a stroke, and what effect keeping blood pressure at normal levels might have on recovery. We will also investigate whether preventing the blood pressure increase after stroke in patients who already have high blood pressure makes them more vulnerable to stroke-induced damage.