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Hypoxia - novel finding turns brain function on its head

The brain is a hungry organ. To fuel brain activity, brain blood flow increases to provide oxygen and nutrients. This matching of blood flow to brain activity is called ‘neurovascular coupling’ and is assumed essential to maintain brain function.

This study took healthy volunteers and challenged their brains by getting them to breathe a gas that contained less oxygen than normal whilst completing a memory task. To compensate for the lack of oxygen being carried by the blood, and to fuel the brain activity, we expected brain blood flow to increase. If it didn’t increase, we expected memory function to decline. Surprisingly, in one part of the brain which is important for memory tasks, called the ‘default mode network’, blood flow reduced yet memory function was maintained. When other cognitive tasks were completed that reduce brain activity in the ‘default mode network’; surprisingly blood flow increased. Thus, a reversal of ‘neurovascular coupling’ was observed.

Our novel finding provides better understanding of ‘neurovascular coupling’ in specific regions of the brain. These findings are exciting because the ‘default mode network’ is associated with changes in structure and function in several common diseases, including dementia. Scientists can now investigate whether altered ‘neurovascular coupling’ is important in patients with such diseases.

This is the first study to show a reversal of neurovascular coupling in the healthy human brain. Full article available here: https://doi.org/10.1177/0271678X20930827

Publication date: 3 July 2020