A new study finds that a cell once believed to serve neurons instead may perform the crucial function of regulating blood flow in the brain. The discovery challenges a basic assumption in neuroscience and could have implications for interpreting brain scans and understanding what occurs during brain trauma and Alzheimer’s disease. Oxygen is the main fuel of biological cells. It is transported throughout the body by way of the circulatory system. Not surprisingly, the brain is one of the most voracious consumers of oxygen, and a basic assumption in neuroscience is that the more active a brain region is, the more oxygen (and thus blood) its neurons require.
Star-shaped brain cells called astrocytes were traditionally thought of as housekeeping cells that helped nourish the brain under the direction of the neurons. The new study found that the astrocytes can directly control blood flow without being told. (Image from a human brain showing an astrocyte (green) reaching out to a blood vessel (yellow). The neurons (blue) are not in direct contact).