NASA Studies Balance In Two Woods Hole Toadfish, A Senator, And Five Astronauts In Shuttle Mission

This experiment is a follow-up to studies conducted on four toadfish sent into space during the Neurolab mission (STS-90) last April.

The scientist responsible for these experiments, Stephen M. Highstein, has been coming to the Marine Biological Laboratory in Woods Hole, Massachusetts, for more than 20 years to study the vestibular system of the toadfish. The vestibular system, which consists of fluid-filled canals in the ears of all vertebrates, provides our sense of balance and equilibrium. (The linings of these canals are covered with hair cells that sense the movement of calcium carbonate crystals known as otoliths. Changes in the position of the head cause the otoliths to move, and the hair cells sense the movement and pass that information along to the brain.)

Information about balance, movement, and location is so critical to animals that the vestibular system was one of the first sensory systems to evolve, says Highstein, an M.D./Ph.D. professor at Washington University School of Medicine who spends his summers doing research at the Marine Biological Laboratory. Not only were the vestibular organs an early invention, but the system of canals and hair cells and otoliths has not changed much over the eons or between vertebrates ranging from toadfish to Senators.

Because the toadfish's vestibular system is very similar to our own, the fish has become a well-known experimental model for learning more about balance disorders such as Meniere's disease and benign paroxysmal positional vertigo. The toadfish is also a good model for studying motion sickness, including that experienced by astronauts during space flight. This is why a few toadfish, in their specially designed aquatic habitats, are joining John Glenn and other Shuttle crewmembers on their journey through space.

The toadfish are fitted with a monitoring system that will enable Highstein to analyze changes to their vestibular system, specifically their otoliths, before, during, and after space flight. Because Glenn and the other astronauts on the flight will experience the same changes in gravity, the data gathered should reveal important information about how the human vestibular system adjusts to microgravity as well.

(More information about the specific experiment can be found at http://shuttlepresskit.com/STS-95/experiment14.htm).

Most of us don't think much about our vestibular system, until it malfunctions. When your vestibular system isn't working - when, for instance, you are suffering from motion sickness-any number of other systems are thrown out of kilter.

"You're lying on your bed," Highstein says, "You're dizzy. Your vision is moving. Your digestion is affected. You certainly have trouble doing any deep thinking..." Virtually all other systems in your body can be affected when your vestibular system misfires-and it often misfires during space flight.

Highstein tried a number of fish before choosing the toadfish as a model when he came to the MBL in the 1970s.

"It was a matter of convenience," he remembers. Toadfish were readily available. They were hardy enough to survive in the lab. And they had an important anatomical advantage over other fish: Their broad, flat head-an ungainly feature that gives Opsanus its monstrous pollywog look-provides space enough for easy-to-sort-out neural wiring.

It turns out that all of these advantages hold true for the toadfish's usefulness as a model for studies in space as well.

The Marine Biological Laboratory, located in Woods Hole, Massachusetts, is an independent scientific institution, founded in 1888, that undertakes the highest level of creative research and education in biology, including the biomedical and environmental sciences.

Visit our Web site at http://www.mbl.edu.

For more information about NASA mission STS-95 see: http://shuttlepresskit.com/