The NASA Performance Assessment Workstation: cognitive performance during head-down bed rest.

The NASA Performance Assessment Workstation was used to assess cognitive performance changes in eight males subjected to seventeen days of 6 degrees head-down bed rest. PAWS uses six performance tasks to assess directed and divided attention, spatial, mathematical, and memory skills, and tracking ability. Subjective scales assess overall fatigue and mood state. Subjects completed training trials, practice trials, bed rest trials, and recovery trials. The last eight practice trials and all bed rest trials were performed with subjects lying face-down on a gurney. In general, there was no apparent cumulative effect of bed rest. Following a short period of performance stabilization, a slight but steady trend of performance improvement was observed across all trials. For most tasks, this trend of performance improvement was enhanced during recovery. No statistically significant differences in performance were observed when comparing bed rest with the control period. Additionally, fatigue scores showed little change across all periods.

Cognitive performance aboard the life and microgravity spacelab.

The impact of microgravity and other stressors on cognitive performance need to be quantified before long duration space flights are planned or attempted since countermeasures may be required. Four astronauts completed 38 sessions of a 20-minute battery of six cognitive performance tests on a laptop computer. Twenty-four sessions were preflight, 9 sessions were in-orbit, and 5 sessions were postflight. Mathematical models of learning were fit to each subject's preflight data for each of 14 dependent variables. Assuming continued improvement, expected values were generated from the models for in-orbit comparison. Using single subject designs, two subjects showed statistically significant in-orbit effects. One subject was degraded in two tests, the other was degraded in one test and exceeded performance expectations in another. Other subjects showed no statistically significant effects on the tests. The factors causing the deterioration in the two subjects can not be determined without appropriate ground-based control groups.

Characterization of the resulting incapacitation following unexpected +Gz-induced loss of consciousness.

+Gz-induced loss of consciousness (G-LOC) results in incapacitation which can be characterized by the unconscious period (absolute incapacitation) and a subsequent period of confusion/disorientation (relative incapacitation). The sum of the absolute and relative incapacitation periods represents the total incapacitation period and may be equated to the overall length of time a pilot would be in uncontrolled flight should G-LOC occur. Reviewing the centrifuge induced G-LOC episodes in 55 subjects allowed a detailed description of G-LOC. The absolute incapacitation period was 16.6 s with the subsequent relative incapacitation being 14.5 s resulting in an overall total incapacitation of 31 s. The G-LOC incapacitation was dependent on the rate of onset of the +Gz-stress and the +Gz level where G-LOC occurred. G-LOC episodes could be subdivided into 2 separate types: Type I being shorter unconsciousness episodes without convulsive movements, and Type II being longer unconsciousness with more frequently associated dream states and convulsive type movements. This detailed description of G-LOC allows a more complete understanding of the phenomenon and establishes the basis for research toward decreasing the resulting incapacitation from G-LOC. Minimizing G-LOC incapacitation and enhancing recovery should enhance safety in the aviation environment of the high-performance-fighter aircraft pilot.