The Vestibular System

The vestibular system maintains balance, keeps vision stable and helps control movements.  Astronauts experience changes in the vestibular system with space flight, and this is manifest as space motion sickness on orbit and temporary balance problems upon return to Earth. Research by NASA on the vestibular system has applications for both astronauts and patients with vestibular problems. 

• On the Neurolab Space Shuttle mission, scientists from the U.S., France and Australia collaborated on a series of sophisticated experiments utilizing a specially built rotating chair and video cameras to measure 3-dimensional eye movements. This technology can be applied to evaluating patients with vestibular diseases.

• Will the inner ear and the connections it makes to the brain develop “normally” in the absence of gravity? NASA research has shown that in several species, the development of the otoliths (a part of the inner ear that senses tilt) is different in microgravity. These studies have discovered a new and unforeseen influence of gravity on the development of the otoliths. There are clinical situations in which humans either lack otoliths or the stones that make up the otolith get into parts of the inner ear where they are not found normally.  In both of these cases, severe clinical symptoms result.  Thus studies of the formation of the otoliths, initiated to study development in the microgravity of space, can give new insight to human clinical concerns.

• To adapt to new situations, the brain has the ability to make new connections or use existing connections in different ways. How this occurs is not understood. NASA-sponsored experiments investigated changes in connections in the portion of the brain which receives input from the vestibular system.  Evidence of rearrangement of these connections was seen in the brain of rats after only one day in orbit.  Extension of these findings may help understand how the nervous system adapts to novel environments, such as the microgravity of space, and could be applied to patients with neurological disease.

• Is there a “critical period” when gravity needs to be present for the inner ear and the connections it makes to develop normally? Recent NASA research suggests that this may be the case.

• The standard system now used to test the human vestibular system employs Computerized Dynamic Posturography, which was developed in the course of NASA funded basic research on the function of the vestibular system.

Thus, basic research on the vestibular system, now of interest to many neuroscientists, has made major contributions to both astronaut crew safety and health, as well as to our knowledge and treatment of human disease. The American Society for Gravitational and Space Biology asks for your support for the Life and Microgravity Sciences research programs of NASA, as we strive to keep America leading the world in utilizing space for improving life.