Lloyd D. Tripp

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A better understanding of how behavioral performance emerges from interacting brain systems may come from analysis of functional networks using functional magnetic resonance imaging. Recent studies comparing such networks with human behavior have begun to identify these relationships, but few have used a time scale small enough to relate their findings to(More)
INTRODUCTION Exposure to microgravity is associated with increased leg venous compliance and reductions in cardiac output, baroreflex functions, and tolerance to orthostatism. However, the effects of chronic exposure to high-G environments are unknown. In addition, there is evidence that females have lower orthostatic tolerance than males, although the(More)
Loss of vigilance may lead to impaired performance in various applied settings including military operations, transportation, and industrial inspection. Individuals differ considerably in sustained attention, but individual differences in vigilance have proven to be hard to predict. The dependence of vigilance on workload factors is consistent with a(More)
Transcranial Doppler sonography was used to measure cerebral blood flow velocity (hemovelocity, CBFV) from the left and right middle cerebral arteries during the performance of 40-min auditory and visual vigilance tasks. Reductions in stimulus duration were the critical signals for detection in both tasks, which were equated for stimulus salience and(More)
Functional near infrared spectroscopy (fNIRS) measures of cerebral oxygenation levels were collected from participants performing difficult and easy versions of a 12 min vigilance task and for controls who merely watched the displays without a work imperative. For the active participants, the fNIRS measurements in both vigilance tasks showed higher levels(More)
BACKGROUND Long-duration space missions, as well as emerging civilian tourist space travel activities, prompted review and assessment of data available to date focusing on cardiovascular risk and available risk mitigation strategies. The goal was the creation of tools for risk priority assessments taking into account the probability of the occurrence of an(More)
OBJECTIVE The aim of this study was to track the course of cerebral tissue oxygen saturation (rSO2) and pilot performance during an episode of gravity-induced loss of consciousness (GLOC). BACKGROUND GLOC, a major problem facing pilots of high-performance aircraft, is brought about by a sudden reduction in rSO2 as a result of increased +Gz force. It(More)
BACKGROUND Ground-based research has investigated the loss of cognitive function in the extreme conditions of G-induced loss of consciousness, however, little is known about pilots' abilities to maintain cognitive performance throughout prolonged conscious exposure in the high-G environment. The effects of fatigue and G layoff on performance during exposure(More)
INTRODUCTION Electroencephalographic (EEG) correlates of Gz-induced loss of consciousness (G-LOC) were examined to better understand the mechanisms of G-LOC. METHODS There were 10 subjects (4 women) who provided 35 G-LOC episodes during which 13 channels of EEG and eye activity were recorded. Subjects simultaneously performed tracking and mathematical(More)
BACKGROUND One of the key factors in maintaining optimal cognitive performance in the high-G environment is the adequate delivery of oxygen to the cerebral tissue. As eye-level blood pressure is compromised at 22 mmHg x G(-1), perfusion to the peripheral cerebral tissues (cerebral cortex) may not be adequate to support the mental demands of flight. This(More)