Read This Before You Sign up for that Space Flight!

--Even though astronauts have toured the universe for decades, scientists are just now beginning to understand how space's low gravity environment can affect the brain. New biological studies show that outer space, at least temporarily, impacts brain mechanisms involved in a variety of functions, including movement and navigation. The research may lead to the development of strategies that protect humans from the consequences of space travel as well as help those with related, earth-based ailments. In addition, the insights on the brain's ability to adapt to aspects of the space assault may help scientists find ways to initiate these adaptations in order to treat a variety of brain disorders.

If technology and science advance at a break-neck pace, recreational trips to outer space in this millennium are a good bet. But before you place a deposit on that moon-travel special, consider how the unusual change in environment, particularly the warp in gravity, could tinker with your brain.

On Earth, gravity's invisible downward force draws us toward the center of the planet and holds us on the surface. This pull, however, barely registers in space.

An increasing amount of biological evidence is now indicating that space's skimpy gravity impacts the brain in a variety of ways. The discoveries are leading to:

An understanding of the importance of gravity on biological systems.
New insight into the brain's ability to adapt to even the strangest situations.
Clues on ways to ward off side effects of space flight as well as some related Earth-based ailments.

For years, researchers have seen signs that space affects the brain. For example, space travelers often experience stints of disorientation and weird visual illusions. They may feel upside down when they are right side up. Travelers also face space motion sickness, marked by dizziness and nausea, and brief disturbances in balance and movement, which occur both in space and upon return to Earth.

In the past few years, scientists decided to take a closer look. A slew of new biological studies now are confirming and starting to explain how space flight influences the brain.

Several experiments have uncovered changes that appear to underlie the movement and balance-related disturbances observed in astronants. One study found that, following 24 hours of space flight, rats had alterations in the cell organization of the cerebellum brain area. This region is critical for learning movements, coordination and balance. As a next step, the researchers are trying to determine if the changes are permanent, even after return to Earth, or whether the reworking of cell communication networks is temporary. Based on those results scientists may be able to find ways to speed up useful cell network adaptations in astronauts, as well as to slow down or prevent destructive adaptations. They also may be able to readjust brains that malfunction from various disorders experienced on Earth.

Other biological studies indicate that space also alters the brain's movement system by changing muscle activity. Unlike Earth, muscles in space don't have to push against a gravity force to maintain upright posture. Research shows that upon re-entry to Earth's environment the alterations trigger shortened steps and tremors. Currently, scientists are developing robotic devices that will train the astronauts' movement systems to better adapt to space flight. These devices may also help people with other types of movement problems that also possibly arise from diminished muscle use.

Other new biological evidence of space's impact relates to astronauts' feelings of disorientation. One study indicates that cells, dubbed place cells, located in the hippocampus brain area are involved. It's thought that place cell activity aids navigation by providing a sort of mental map of the enviornment. Scientists found, however, that the cell activity goes out of whack in rats during the early days of space flight when they try to complete a three-dimensional maze. Further insights may help researchers find ways to prevent disorientation in astronauts and tackle hippocampus-related disorders on Earth.

Early biological findings also hint that space may influence the overall activity of cells throughout the brain. A preliminary analysis of mice embryos collected in space uncovered alterations in some essentials of cell function, such as basic metabolic processes and internal movements of the cell nucleus. Researchers hope to determine if the changes also occur in adults and if they affect overall abilities.

These and other insights are launching the understanding of the brain into a new orbit, so hold on to your seat.

Specific brain areas that undergo changes when exposed to space flight include the cerebellum and hippocampus, according to new studies. The cerebellum, tucked away in the back of the brain, is important for coordination and balance. Deep in the brain, the seahorse-shaped hippocampus is critical for certain memory functions including those for navigation.

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