TITLE: Countermeasures to regain gravity sensing after ear manipulations
Gravity perception is altered during exposure to microgravity in spaceflight. In microgravity, all linear acceleration is associated with angular acceleration as all linear acceleration results from centrifugal forces acting upon the ear when heads or bodies move in space. Upon return to Earth and gravity, the brain interprets gravity as being related to angular acceleration, affecting balance and gaze stabilization for several days. We have developed a new frog model system that, through various ear transplantations or genetic/pharmacological manipulations, uncouples linear and angular acceleration analogous to astronauts return to Earth, and also mimics the age-related hair cell loss in the elderly. Our various manipulations will produce asymmetrical movement/gravitational input to the animal. We have developed a system for systematically monitoring the effect of asymmetrical input on motor output through analysis of the swimming behavior of tadpoles. We then will provide a training program using a frog-elevator, in analogy with parabolic flight, or using the ultracentrifuge at NASA Ames, to determine whether alternation of gravitational sensation or increased gravitational input respectively can serve as a training module to regain symmetrical motor output. The goal would be for this training program to help astronauts regain motor function more rapidly upon return to Earth and also help the elderly, who suffer age-related hair cell loss in the inner ear, improve their balance. This project involved cooperation of students across two different departments (Biology and Engineering) at the University of Iowa.