By blowing gentle puffs of air onto a mouse's whiskers and watching how its brain reacts, scientists are discovering that a long-overlooked signaling system in the brain is crucial to our everyday activity.
The work is the latest in a growing body of evidence that star-shaped brain cells known as astrocytes aren't simply support cells but are stars of the brain in their own right, say researchers at the University of Rochester Medical Center who did the study. The work will be reported in a paper in the June issue of Nature Neuroscience and is now available online.
"Now people have to take astrocytes seriously," said Maiken Nedergaard, M.D., Ph.D., professor in the Department of Neurosurgery and a member of the Center for Aging and Developmental Biology, whose team did the research. In the past few years she has found that the cells, long thought to simply nourish other cells and clean up their wastes, are central to diseases like epilepsy, spinal cord injury, and maybe even Alzheimer's disease.
For decades scientists have studied the swift signaling activity of the brain's better-known cells, the neurons, by recording their electrical activity. But astrocytes don't fire in the same way, and conventional techniques don't record their activity. Many scientists looked at this "silence" as evidence that astrocytes weren't communicating much, and they assumed that astrocytes, which are 10 times as plentiful as neurons, simply don't make up an important signaling network.
So Nedergaard devised a new way to "listen" for astrocyte activity, developing a sophisticated laser system to look at their activity by measuring the amount of calcium inside the cells. By listening in the right way, her team has made a series of discoveries that have brought the once-obscure astrocyte and its signaling capability into prominence.
In the latest work, graduate student Xiaohai Wang, M.D., led a team that focused the laser system on the brain cells of mice as their whiskers were gently pushed about with gentle puffs of air. Whiskers make up one of the most important information-gathering mechanisms that many animals have, used in much the same way that people rely on their hands and eyes to learn about their environment. A large part of a mouse's brain is devoted to processing the information their whiskers send its way - a change in air current might indicate a nearby predator, for instance, or a certain texture might indicate a yummy bite of cheese nearby. Scientists have found that the way an animal's brain learns information from its whiskers mirrors the way people learn from their senses.