Sensorimotor performance and computational demand during short-term exposure to microgravity.

INTRODUCTION: Previous research suggests that human sensorimotor performance depends both on task difficulty, and on the allocation of the brain's computational resources to the task. We employ this view to analyze the changes of sensorimotor performance during the microgravity episodes of parabolic flight.
METHODS: There were seven subjects who participated before, during, and after exposure to the microgravity episodes of parabolic flight. They performed a tracking task with one hand, and a four-choice reaction time task with the other hand, either alone or concurrently. Overall performance scores across tasks were calculated.
RESULTS: Overall single-task performance deteriorated by about 50% microgravity, with little sign of recovery during the flight. Overall dual-task interference was more than twice as great at the onset of microgravity than at the onset of the 1-G baseline, but converged toward that baseline within about 4.5 min.
CONCLUSIONS: Our subjects accepted a consistently poor level of sensorimotor performance throughout exposure to microgravity. To maintain that level, they increased the allocation of computational resources to the tasks at the onset of microgravity, but an increase was no longer necessary after 4.5 min of microgravity exposure. We take the initial increase as evidence of a brief phase of sensorimotor adaptation.