Heart rate variability in novice pilots during and after a multi-leg cross-country flight.

Background: A pilot's workload induces autonomic nervous system modulations which could be related to a decrease of vigilance that could impair safety. Kinetics during flight and recovery are not well known.

Objective: The aim of this study was to assess linear and nonlinear heart rate variability (HRV) modulations and vigilance during a high mental workload induced by a complex flight and subsequent recovery.

Short half-life hypnotics preserve physical fitness and altitude tolerance during military mountainous training.

Objective: We study the effect of short half-life hypnotics (zaleplon or zolpidem against placebo) on altitude tolerance in 12 nonacclimated male soldiers (age, 22.1 +/- 0.8 years; height, 177.

Operational impact of health problems observed during a four-month military deployment in Ivory Coast.

Diseases always have a significant impact during military deployments. We evaluated the operational impact of health problems observed in a French infantry battalion (n = 690) during a 4-month assignment in Ivory Coast. In all, 55.

Heart rate and autonomic balance during stand tests before and after fighter combat missions.

Background: High workload during combat missions is a critical factor in the use of modern aircraft. Our objective was to evaluate the impact of piloting in war zones on the kinetics of the sympathovagal balance during recovery.

Methods: There were 40 military pilots who were monitored during operational flights in Afghanistan.

The vastus lateralis neuromuscular activity during all-out cycling exercise.

Objective: The objective of this work was to study modifications in motor control through surface electromyographic (sEMG) activity during a very short all-out cycling exercise.

Methods: Twelve male cyclists (age 23+/-4 years) participated in this study. After a warm-up period, each subject performed three all-out cycling exercises of 6s separated by 2 min of complete rest.

A dynamic network involving M1-S1, SII-insular, medial insular, and cingulate cortices controls muscular activity during an isometric contraction reaction time task.

Magnetoencephalographic, electromyographic (EMG), work, and reaction time (RT) were recorded from nine subjects during visually triggered intermittent isometric contractions of the middle finger under two conditions: unloaded and loaded (30% of maximal voluntary contraction). The effect of muscle fatigue was studied over three consecutive periods under both conditions. In the loaded condition, the motor evoked field triggered by the EMG onset decreased with fatigue, whereas movement-evoked fields (MEFs) increased (P < 0.

Zaleplon and zolpidem objectively alleviate sleep disturbances in mountaineers at a 3,613 meter altitude.

Study Objectives: To assess the effects of zolpidem and zaleplon on nocturnal sleep and breathing patterns at altitude, as well as on daytime attention, fatigue, and sleepiness.

Design: Double-blind, randomized, placebo-controlled, cross-over trial.

Setting: 3 day and night alpine expedition at 3,613 m altitude.

Stress modulation of the memory retrograde-enhancing effects of the awakening drug modafinil in mice.

Purpose: This study investigated the dose-effect relationship of modafinil administration on contextual memory processes, in parallel with the measurements of plasma corticosterone levels in acutely stressed mice.

Materials And Methods: Memory was first evaluated in normal (nonstressed) mice either in contextual (CSD) or spatial (SSD) tasks. Thus, C57 Bl/6 Jico mice learned two consecutive discriminations (D1 and D2) in a four-hole board.

Brief exposure to -2 Gz reduces cerebral oxygenation in response to stand test.

The aim of the present experiment was to determine whether a single 30 s of exposure to -2 Gz (foot-to-head inertial forces) as orthostatic stress results in altered brain oxygenation control in response to active standing. Cerebral oxygenation (oxy-Hb), cerebral blood volume (CBV), and mean arterial blood pressure at brain level (MAPbrain) were recorded in 12 subjects in supine and then in standing position (10 min), before and after -2 Gz centrifugation. The decrease in oxy-Hb (-5 +/- 9 vs.

Modafinil restores memory performance and neural activity impaired by sleep deprivation in mice.

The original aims of our study have been to investigate in sleep-deprived mice, the effects of modafinil administration on spatial working memory, in parallel with the evaluation of neural activity level, as compared to non-sleep-deprived animals. For this purpose, an original sleep deprivation apparatus was developed and validated with continuous electroencephalography recording. Memory performance was evaluated using spontaneous alternation in a T-maze, whereas the neural activity level was estimated by the quantification of the c-Fos protein in various cerebral zones.

Modafinil-induced modulation of working memory and plasma corticosterone in chronically-stressed mice.

The original aims of our study were to investigate the dose-effect relationship of modafinil administration on working memory performance, in parallel with the measurement of plasma corticosterone in chronically-stressed mice, as compared to control mice. Memory performance was evaluated by spontaneous alternation in a T-maze. Vehicle or modafinil (8, 16 or 32 mg/kg) were administered after or without chronic stress (immobilization and exposure to light) for 15 min/day over a period of consecutive 14 days.

Aerobatic flight effects on baroreflex sensitivity and sympathovagal balance in experienced pilots.

Background: Aerobatic flights subject pilots to accelerations and, therefore, to heavy physical workloads.

Objective: Our aim was to document changes in spontaneous baroreflex sensitivity and disturbances of sympathovagal balance after exposure to "push-pull" accelerations.

Methods: During 30-min flights, five aerobatic pilots performed five series of descending spirals: first, 30 s under negative (-3 Gz max), and then 30 s under positive (+4 Gz max) G loading, climbing between each series to regain altitude.

Cerebral oxygenation declines despite maintained orthostatic tolerance after brief exposure to gravitational stress.

We examined the effect of a single 120 s of exposure to +3Gz (head-to-foot inertial forces) centrifugation as orthostatic stress on cerebral oxygenation (oxy-Hb) and cerebral blood volume (CBV) changes in response to stand test, in order to relate the occurrence of altered cerebral oxygenation control to any increase in sympathetic activity. Frontal near-infrared spectroscopy and mean arterial blood pressure at brain level (MAPbrain) were recorded in 14 subjects in supine and then in standing (10 min) position, before and after +3Gz centrifugation. The decrease in oxy-Hb (-7 +/- 5 a.

EEG and ECG changes during simulator operation reflect mental workload and vigilance.

Background: Performing mission tasks in a simulator influences many neurophysiological measures. Quantitative assessments of electroencephalography (EEG) and electrocardiography (ECG) have made it possible to develop indicators of mental workload and to estimate relative physiological responses to cognitive requirements.

Objective: To evaluate the effects of mental workload without actual physical risk, we studied the cortical and cardiovascular changes that occurred during simulated flight.

EEG and ECG changes during selected flight sequences.

Background: Mental workload has become a critical factor in the design and use of modern aircraft. Because of the complexity of the human-machine system, it is necessary to determine workload, fatigue, and level of performance using noninvasive electrophysiological measures.

Objective: Our objective was to identify the electrophysiological indicators of mental workload during piloting tasks.

Analysis of heart rate variability after a ranger training course.

We studied the effects of prolonged physical activities on resting heart rate variability (HRV) during a training session attended by 23 cadets of the French military academy. This course lasts 1 month and is concluded by a 5-day field exercise simulation with physical and psychological stress. Data collection took place before (B) and immediately at the end (E) of the course.

Declarative memory impairments following a military combat course: parallel neuropsychological and biochemical investigations.

The aim of this study was to investigate the impact on several forms of memory and metabolism of a 5-day combat course including heavy and continuous physical activities and sleep deprivation. Mnemonic performance and biochemical parameters of 21 male soldiers were examined before and at the end of the course. Our results showed that short-term memory (memory span, visual memory, audiovisual association) and long-term memory were significantly impaired, whereas short-term spatial memory and planning tasks were spared.