What controls blood flow in the brain?

What controls blood flow in the brain?
When neurons become active, they call for an extra boost of oxygenated blood – this change in the presence of blood in different regions of the brain is the basis for functional brain scans. However, what controls this increase or decrease in blood supply has been a long-standing debate.

In a paper published on June 25 in Neuron, Yale University scientists present the strongest evidence yet that smooth muscle cells surrounding blood vessels in the brain are the only cells capable of contracting to control blood vessel diameter and thus regulate blood flow. This basic anatomical understanding may also have important implications for phenomena observed in stroke and migraines.

Smooth muscle cells line the thicker blood vessels in the brain, while the branching capillaries are covered by a mysterious cell type called pericytes. Pericytes are not muscle cells or neurons, but they are found in large numbers in the brain and are thought to play a role in blood vessel formation. Previous studies have suggested that pericytes could contract to regulate blood flow in the smaller blood vessels, but the new Neuron paper contradicts this theory.

Source and further reading:
http://www.eurekalert.org/pub_releases/2015-06/cp-wcb061915.php 

Image:
Specialized microscope looking into the live mouse brain reveals that smooth muscle cells (cyan) surrounding blood vessels abnormally constrict during and after stroke causing permanent vessel blockage. This phenomenon could worsen the injury in stroke and provides a new target for potential drugs to improve stroke outcome.

#bloodflow   #neuroscience   #pericytes