Feeding the brain

摘要

Like all tissues, our brains need energy to function, and this comes in the form of oxygen and glucose, carried in the blood. The brain's information-processing capacity is limited by the amount of energy available, so, as has been recognized for more than a century, blood flow is increased to brain areas where nerve cells are active. This increase in flow provides the basis for functional magnetic resonance imaging of brain activity, but exactly how the flow is increased is uncertain. On page 195 of this issue, Mulligan and MacVicar3 reveal a previously unknown role for non-neuronal brain cells called astrocytes in controlling the brain's blood flow. Intrigu-ingly, the new data contradict a previous suggestion for how astrocytes regulate flow.