It appears that the fluid around the brain may do more than absorb shock and protect the brain from damage -- but researchers aren't sure what.

A study at the University of Maryland at Baltimore has found that cerebrospinal fluid, which bathes the brain and spinal cord, moves rapidly through the brain as if it were pumped. And because there are chemical messengers contained in the fluid, the flow may play a role in emotions, thought and behavior.

"A lot of neurological problems, particularly vascular problems like stroke, have associations with these shifts in fluid," said Dr. Marshall Rennels. "But what this means at this point in clinical treatment is really hard to nail down."

Rennels' experiments traced the flow of certain proteins through the brains of animals.

So far, scientists know more about how the fluid moves than why. The pumping effect seems to result from the pulsing of arteries in the brain. The fluid goes through the brain along the outside of the blood vessels.

While the presence of neurotransmitters in the fluid was once thought to be merely leakage from the brain, Rennels' research suggests that they may "actually be delivered to specific sites" by the fluid.