title: Accuracy of aimed arm movements in changed gravity.
abstract: We studied the accuracy of aimed arm movements in normal gravity, and during the hypergravity (hyper-G) and microgravity (micro-G) episodes of KC-135 parabolic flights. Subjects pointed at mirror-viewed targets without sight of their arm, and final pointing position was measured by a digitizing pad. Compared with the normal gravity (normal-G) baseline, subjects pointed consistently higher in hyper-G, and still higher in micro-G. Results were not different if subjects viewed targets only during normal-G and pointed at their memorized position under changed gravity (changed-G); this suggests that the "elevator illusion" played a minor role in our study. The observed impairments were attributed to degraded proprioceptive feedback and/or inappropriate motor programs in changed-G. Pointing accuracy improved movement-to-movement but not parabola-to-parabola, indicating that prolonged exposure is needed for sustained adaptation.
authors.affiliation: Institute for Space and Terrestrial Science, York University, North York, Ont., Canada.
authors.forename: O
authors.initials: O
authors.lastname: Bock
authors.forename: I P
authors.initials: IP
authors.lastname: Howard
authors.forename: K E
authors.initials: KE
authors.lastname: Money
authors.forename: K E
authors.initials: KE
authors.lastname: Arnold
mesh_terms: D000337:Aerospace Medicine; D001132:Arm; D006112:Gravitation; D006801:Humans; D008433:Mathematics; D009068:Movement; D011597:Psychomotor Performance