The brain, in turn, is under tremendous stress, developing a voracious appetite for oxygen as it works frantically to restore the proper chemical balance. Oxygen-rich blood pours into the area to allow brain tissue to work overtime; the team found that the brain’s arteries expand by more than 50 percent to keep up with the demand.
It’s at this stage that Nedergaard observed the unexpected: While blood flow increased, bringing more oxygen overall to the brain, there were still pockets of severe hypoxia. The brain was working so hard to restore the chemical balance and to resume normal cellular function, using so much oxygen, that the brain simply couldn’t keep up with the demand.
“Basically, even though the body has really stepped up the availability of oxygen, the brain’s demands for oxygen are suddenly so great that the blood vessels in the brain can’t keep up,?said Nedergaard. “It’s a mismatch between supply and demand.?
Brain tissue closest to the oxygen-rich blood vessels soaks up the oxygen as fast as they can, leaving tissues further away with a diminished supply. It’s like a pride of lion cubs fighting for their mother’s milk ?a few may get nudged away, go without, and will eventually die. In a brain in the midst of cortical spreading depression, brain cells closest to oxygen-rich blood vessels survive, while cells further away don’t get access to the oxygen and are in jeopardy.
“People have always thought that in order to treat a migraine, you treat the pain. We’re going beyond that. Migraines could be dangerous. The focus should be on prevention,?said Nedergaard, who notes that by the time a person feels pain or notices a visual distur
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Source:University of Rochester Medical Center