Blood vessels within a sensory area of the mammalian brain loop and connect in unexpected ways, a new map has revealed.
The study, published June 9 in the early online edition of Nature Neuroscience, describes vascular architecture within a well-known region of the cerebral cortex and explores what that structure means for functional imaging of the brain and the onset of a kind of dementia.
David Kleinfeld, professor of physics and neurobiology at the University of California, San Diego, and colleagues mapped blood vessels in an area of the mouse brain that receives sensory signals from the whiskers.
The organization of neural cells in this brain region is well-understood, as was a pattern of blood vessels that plunge from the surface of the brain and return from the depths, but the network in between was uncharted. Yet these tiny arterioles and venules deliver oxygen and nutrients to energy-hungry brain cells and carry away wastes.
The team traced this fine network by filling the vessels with a fluorescent gel. Then, using an automated system, developed by co-author Philbert Tsai, that removes thin layers of tissue with a laser while capturing a series of images to reconstructed the three-dimensional network of tiny vessels.
The project focused on a region of the cerebral cortex in which the nerve cells are so well known that they can be traced to individual whiskers. These neurons cluster in "barrels," one per whisker, a pattern of organization seen in other sensory areas as well.
The scientists expected each whisker barrel to match up with its own blood supply, but that was not the case. The blood vessels don't line up with the functional structure of the neurons they feed.
"This was a surprise, because the blood vessels develop in tandem with neural tissue," Kleinfeld said. Instead, microvessels beneath the surface loop and connect in patterns that don't obviously correspond to the
|Contact: David Kleinfeld|
University of California - San Diego