Researchers from the UA and NASA are studying rats' mental patterns to help astronauts work longer in space without becoming disoriented.

In space, astronauts are constantly trying to re-orient themselves because compass directions lose all meaning.

"Humans weren't meant to think in three-dimensions," said Bruce McNaughton, psychology professor and project researcher.

Space sickness is part of life for astronauts and is caused when the vestibular region of the inner ear loses the normal directional cues, which gravity and two-dimensional space provide, said Eric Carmichel, an intern at the hearing clinic, a division of the Department of Speech and Hearing Sciences.

Carmichel said sensors in the inner ear are floating in fluids that respond to changes in movement. When people turn their heads, the fluid sways the sensors in the direction of the motion - telling the brain which way they are going.

The zero-gravity environment of space disrupts this internal guidance system by allowing astronauts to change direction without turning their heads, McNaughton said.

This is possible because, in space, astronauts can move by pitching (floating) instead of turning their heads side-to-side as we do on Earth, he said.

In an effort to combat problems with spatial orientation, the UA's Neural Systems, Memory and Aging research lab, NSMA, teamed with NASA two years ago to study the navigational systems in the brain, McNaughton said.

The research involves monitoring the brain patterns of rats "to figure out what logic the brain uses to navigate," said Doug Nitz, a post-doctoral researcher at the lab.

The rats are surgically fitted with a cap containing groups of four wires, each no thicker than a human hair, that are lowered into the brain to record the firing pattern of the cells, he said.

"The rat is not in any pain. Basically, he doesn't notice the wires," Nitz said.

The rats are then placed in a maze, and as they move through the maze, certain "place cells" fire in their brains. The same cells always fire in the same location and order if the rat follows the same path. This creates the rat's internal map, McNaughton said.

If the lights are turned out, the cells still fire, but soon the rat becomes confused. The rat needs a visual cue to keep it on track.

For example, if you know Mt. Lemmon is north of Tucson, you have formed a visual association between that mountain and north. If Mt. Lemmon disappeared, it would probably take you a few minutes to reorient yourself.

In space, the problem is that the astronauts have no fixed reference points, McNaughton said.

NASA has largely overcome this problem on the space shuttle by training astronauts to associate the cockpit with north, the floor with down and so on, he said.

However, with plans to build a permanent space station sometime in the next century, NASA will need astronauts to work long hours in open space without becoming disoriented, McNaughton said.

In preparation for extended space trips, NASA will launch a shuttle mission called "Neurolab" in 1998. The UA's brain cell research will be an integral part of the mission.

While in orbit on the space shuttle, the rats will be led through the mazes in a way that requires them to make three hard, 90-degree turns and pitch (float) through one turn.

This means the rat will complete a full circle and be looking at the same visuals it saw at the beginning. However, because it floated through one turn, the inner ear and brain will not have recorded the turn, McNaughton said. Eventually the rats will be lost because the visual cues and the internal mental map do not match, he said.

If this research is successful, scientists and engineers will begin developing alternative navigational tools to help astronauts avoid the same confusion the rats are expected to experience.

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