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Biomedical subjects

D Manzey

Publications and source records attributed to D Manzey.

At least 19 recordsLinked to original sources
PubMed2000

Impairments of manual tracking performance during spaceflight: more converging evidence from a 20-day space mission.

Studies of human performance during spaceflight have consistently revealed degradations of manual tracking performance in space. The present investigation analysed these performance decrements in more detail by applying frequency-response analyses of tracking performance. It was hypothesized that tracking impairments result from two factors: at an early adaptation phase in space they primarily reflect effects of microgravity on human visuo-motor processes, whereas later into the mission they are also caused by impairments of attentional processes induced by cumulative workload and fatigue. In order to investigate this hypothesis, performance of one cosmonaut in a first-order unstable tracking task was repeatedly assessed before, during and after a 20-day space mission. Single-case statistical analyses revealed the following effects: tracking performance declined at the first assessment in space and in two later inflight sessions compared to pre-flight baseline. Whereas the early tracking decrement was mainly due to an increase of the effective time-delay during tracking and accompanied by only minor changes of mood or workload, one of the later inflight impairments was due to an increase of effective time-delay, a decreased tracking gain, and an increase of tracking remnant, and both were associated with considerably higher workload ratings. This pattern of effects supports the two-factor hypothesis.

Adult↗
PubMed2000

Monitoring of mental performance during spaceflight.

Mental performance of astronauts during spaceflight may suffer from both direct effects of microgravity on perceptual, cognitive, and psychomotor processes, and unspecific stress effects on these functions due to high workload sleep disturbances, or the general burden of adapting to the extreme living conditions in space. Early detection of any signs of mental performance impairments seems to be essential for mission success and to prevent obvious performance decrements in critical mission tasks. One possible approach to this problem is to assess the astronaut's performance on specific screening tests repeatedly during a space mission and to compare the results with a self-referenced baseline established pre-flight. The selection of screening tests for this purpose should be guided by three different criteria: 1) their reliability; 2) their sensitivity (i.e., their power to reveal subtle mental performance changes induced by internal or external stressors during spaceflight); and 3) their diagnosticity (i.e., their capability to reveal the underlying processes that lead to these performance deficits). Based on a discussion of these theoretical issues, first attempts to monitor mental performance of astronauts during spaceflight by means of short-term laboratory tasks are reviewed. The results of these studies suggest that, in particular, perceptual-motor tasks (tracking) and tasks placing comparatively high demands on attentional processes (e.g., dual-tasks) represent sensitive monitoring measures. First studies on the diagnositicity of tracking performance decrements during spaceflight suggest that they reflect both microgravity-related changes in the sensory-motor system as well as unspecific stress-effects, with the former factor reflected primarily in tracking performance decrements during early adaptation to the microgravity environment.

Attention↗
PubMed2000

Summary of research issues in monitoring of mental and perceptual-motor performance and stress in space.

This article describes the papers presented in the workshop that cover the monitoring of stress and perceptual-motor performance. Monitoring is necessary for early detection and intervention of individual and group stress, especially on long-term missions. Test batteries will need to be developed that provide diagnostic information about the cause of deficits so that countermeasures can be applied.

Humans↗
PubMed1999

Changed visuomotor transformations during and after prolonged microgravity.

A series of step-tracking experiments was conducted before, during, and after a 3-week space mission to assess the effects of prolonged microgravity on a non-postural motor-control task. In- and post-flight accuracy was affected only marginally. However, kinematic analyses revealed a considerable change in the underlying movement dynamics: too-small force and, thus, too-low velocity in the first part of the movements was mainly compensated by lengthening the deceleration phase of the primary movement, so that accuracy was regained at its end. The observed in-flight decrements in peak velocity and peak acceleration point to an underestimation of mass, in agreement with the re-interpretation hypothesis of Bock et. al. Post-flight no reversals of the in-flight changes (negative aftereffects) were found. Instead, there was a general slowing down, which could be due to post-flight physical exhaustion.

Adult↗
PubMed1998

Mental performance during short-term and long-term spaceflight.

During the last years several attempts have been made to describe changes in the mental efficiency of astronauts during space missions by means of performance monitoring studies. These studies are characterized by repeated multivariate assessment of different functions of the human information-processing system. In the present paper, a first review of performance monitoring studies during short-term and long-term spaceflight is given. Despite the comparatively small number of studies, a fairly consistent pattern of effects can be derived: Whereas no or only slight impairments of elementary and complex cognitive functions or spatial processing were found in space, clear disturbances could be identified in visuo-motor tracking and dual-task performance. Both of these latter effects appear to be closely related to adaptation to altered gravity conditions. General issues of this strategy of research are discussed which concern the disentanglement of microgravity-related effects and unspecific stress effects on mental performance under conditions of spaceflight. In addition, possible mechanisms which may be responsible for tracking disturbances under microgravity are discussed, and some directions for future human performance research in space are outlined.

Humans↗
PubMed1998

Mental performance in extreme environments: results from a performance monitoring study during a 438-day spaceflight.

During their stay in a space habitat, astronauts are exposed to many different stressors that may entail detrimental effects on mood and performance. In order to monitor the effects of the space environment on different human information processing functions during an extraordinary long-term space mission, the cognitive. visuo-motor and time-sharing performance of one Russian cosmonaut was repeatedly assessed (29 times) during his 438-day stay in space. The performance tasks used were chosen from the AGARD-STRES battery and included grammatical reasoning, Sternberg memory-search, unstable tracking, and a dual-tasks consisting of unstable tracking with concurrent memory-search. In addition to performance assessment, several subjective ratings concerning mood and workload were collected. Comparisons of pre-flight, in-flight, post-flight and two follow-up assessments 6 months after the mission revealed, (1) no impairments of basic cognitive functions during the flight, (2) clear impairments of mood, feelings of raised workload, and disturbances of tracking performance and time-sharing during the first 3 weeks in space and the first 2 weeks after return to Earth, (3) an impressive stability of mood and performance during the second to fourteenth month in space, where mood and performance had returned to pre-flight baseline level, and (4) no long-lasting performance deficits at follow-up assessments. From these results it is concluded that the first 3 weeks of long-term spaceflights and the first 2 weeks back on Earth represent critical periods where adverse effects on attentional processes are to be expected, induced by the demands to adjust to the extreme environmental changes. The stability of mood and performance observed after successful adaptation to the space environment indicates that mental efficiency and emotional state can be maintained on a level as high as on Earth even during extraordinary long-term space missions.

Adaptation, Psychological↗
PubMed1998

Joint NASA-ESA-DARA Study. Part three: effects of chronically elevated CO2 on mental performance during 26 days of confinement.

BACKGROUND: Short-term exposures to increased CO2 concentrations in breathing air up to 5% are assumed to have only negligible behavioral effects. In the present study it was examined to what extent prolonged exposures to moderately elevated levels of CO2 in the ambient air affect human performance. METHOD: During two phases of 26 d of confinement in a diving chamber a group of four subjects was exposed to two different levels of CO2 (0.7% and 1.2%). Cognitive, visuo-motor, and time-sharing performance were assessed repeatedly before, during, and after the exposure by means of a task battery including grammatical reasoning, memory search, unstable tracking, and dual tasks. In addition, subjective workload and mood ratings were collected. A second group of four subjects served as a control group who performed the different tasks on the same 26-d time schedule without being exposed to confinement and elevated CO2. RESULTS: During exposure to 0.7% CO2 only tracking performance was slightly disturbed compared with baseline levels, whereas performance of the control group remained stable. The time course of this effect suggested that it was related to chamber adaptation rather than to increased levels of CO2. During exposure to 1.2% CO2, tracking performance again was significantly impaired. In contrast to the lower exposure condition, the time course of this effect appeared to be related to the CO2 load and covaried with a loss of subjective alertness. CONCLUSIONS: The study indicates that at least visuomotor performance might be affected by CO2 concentrations in the ambient atmosphere as small as 1.2% if subjects are chronically exposed to these concentrations in a confined environment. The strength of these effects, however, does not appear to be of operational relevance.

Adult↗
PubMed1997

Two-crew operations: stress and fatigue during long-haul night flights.

BACKGROUND: As part of a research program concerning legal aspects of two-pilot operations on long-haul routes, the purpose of the study was to investigate two-crew extended range operations during a flight roster with two consecutive night flights and a short layover. HYPOTHESIS: Present flight time regulations may not be adequate for two-crew minimum operations. METHODS: The study was conducted in cooperation with a German airline company on the route Frankfurt (FRA)-Mahe (SEZ). There were 11 rotations (22 flights) that were investigated by pre-, in- and post-flight data collection each time from the two pilots. Recordings included sleep, taskload, fatigue and stress by measurement of EEG, ECG, motor activity, and subjective ratings. The average actual flight times were 9:15 h (FRA-SEZ) and 9:53 h (SEZ-FRA). All flights took place at night. The layover duration in Mahe was 13:30 h during day-time. RESULTS: During layover, sleep was shortened by 2 h on average compared with 8-h baseline sleep. The two consecutive night duties resulted in a sleep loss of 9.3 h upon return to home base. Inflight ratings of taskload showed moderate grades, but for fatigue ratings an increasing level was observed. Fatigue was more pronounced during the return flight and several pilots scored their fatigue at a critical level. Motor activity, brainwave activity (occurrences of micro-events) and heart rate indicated drowsiness and a low state of vigilance and alertness during both night flights, but these effects were more pronounced during the second flight. CONCLUSIONS: From the findings it is concluded that a duty roster, as conducted in this study, may impose excessive demands on mental and physiological capacity.

Adult↗
PubMed1996

Performance and brain electrical activity during prolonged confinement.

A subset of the AGARD-STRES battery including memory search, unstable tracking, and a combination of both tasks (dual-task), was applied repeatedly to the four chamber crew members before, during, and after the 60-day isolation period of EXEMSI. Five ground control group members served as a control group. A subjective state questionnaire was also included. The results were subjected to a quantitative single-subject analysis. Electroencephalograms (EEG) were recorded to permit correlation of changes in task performance with changes in the physiological state. Evaluation of the EEG focused on spectral parameters of spontaneous EEG waves. No physiological data were collected from the control group. Significant decrements in tracking ability were observed in the chamber crew. The time course of these effects followed a triphasic pattern with initial deterioration, intermediate recovery to pre-isolation baseline scores after the first half of the isolation period, and a second deterioration towards the end. None of the control group subjects displayed such an effect. Memory search (speed and accuracy) was only occasionally impaired during isolation, but the control group displayed a similar pattern of changes. It is suggested that a state of decreased alertness causes tracking deterioration, which leads to a reduced efficiency of sustained cue utilization. The assumption of low alertness was further substantiated by higher fatigue ratings by the chamber crew compared to those of the control group. Analysis of the continuous EEG recordings revealed that only two subjects produced reliable alpha wave activity (8-12 Hz) over Pz and, to a much smaller extent, Fz-theta wave activity (5-7 Hz) during task performance. In both subjects Pz-alpha power decreased consistently under task conditions involving single-task and dual-task tracking. Fz-theta activity was increased more by single-task and dual-task memory search than by single-task tracking. The alpha attenuation appears to be associated with an increasing demand on perceptual cue utilization required by the tracking performance. In one subject marked attenuation of alpha power occurred during the first half of the confinement period, where he also scored the highest fatigue ratings. A striking increase in fronto-central theta activity was observed in the same subject after six weeks of isolation. The change was associated with an efficient rather than a degraded task performance, and a high rating of the item "concentrated" and a low rating of the item "fatigued." This finding supports the hypothesis that the activation state associated with increased fronto-central theta activity accompanies efficient performance of demanding mental tasks. The usefulness of standardized laboratory tasks as monitoring instruments is demonstrated by the direct comparability with results of studies obtained from other relevant research applications using the same tasks. The feasibility of a self-administered integrated psychophysiological assessment of the individual state was illustrated by the nearly complete collection of data. The large number of individual data collected over the entire period permitted application of quantitative single-subject analysis, allowing reliable determination of changes in the individual state in the course of time. It thus appears that this assessment technique can be adapted for in-flight monitoring of astronauts during prolonged spaceflights. Parallel EEG recording can provide relevant supplementary information for diagnosing the individual activation state associated with task performance. The existence of large individual differences in the generation of task-sensitive EEG rhythms forms an important issue for further studies.

Adult↗
PubMed1995

Dual-task performance in space: results from a single-case study during a short-term space mission.

During spaceflights, astronauts are exposed to many stressors (e.g., microgravity, confinement) that may impair human information-processing capabilities. In order to analyze the possible effects of the space environment on human time-sharing efficiency, a single-case experiment was conducted in which the time course of dual-task performance (unstable tracking with concurrent memory search) of one space crew member was monitored repeatedly (13 times) throughout an 8-day space mission. Tasks were taken from the Advisory Group for Aerospace Research and Development battery of Standardized Tests for Research with Environmental Stressors. Comparisons of in-flight, preflight, and postflight performance revealed no decrements in single-task memory search performance but did reveal clear impairments in single-task tracking and dual-task performance. From these results we conclude that psychomotor processes and higher attentional functions are particularly prone to disturbance effects in space.

Adult↗
PubMed1993

Behavioral aspects of human adaptation to space: analyses of cognitive and psychomotor performance in space during an 8-day space mission.

Living in the space environment and exposure to microgravity induce a number of effects that may interfere with human cognitive and psychomotor performance. However, up to now very few attempts have been made to monitor possible impairments of human performance during space missions. In the present single-case study several cognitive and psychomotor functions were monitored during an 8-day space mission to an orbital station using a computerized performance monitoring device. This device included four different tasks, which were selected from a battery of Standardized Tests for Research with Environmental Stressors published recently by the NATO Advisory Group for Aerospace Research and Development, and which demanded logical reasoning and decision-making functions, memory retrieval functions, and fine manual control. Each task was performed 23 times (6 preflight, 13 inflight, 4 postflight sessions). By means of single-subject statistics inflight performance was compared with baseline performance during pre- and postflight sessions. In accordance with the few previous performance studies conducted during space flights, speed and accuracy of short-term memory retrieval and logical reasoning functions remained unimpaired during the stay in space. However, clear decrements in tracking performance were found, showing to increased difficulties in fine manual control. These results suggest that performance decrements in space may arise primarily in psychomotor functions due to alterations requiring an effortful accommodation of motor skills which had been acquired under 1-g conditions to the new conditions of microgravity.

Adaptation, Psychological↗
PubMed1992

Psychological training of German science astronauts.

Although the significance of psychosocial issues of manned space flights has been discussed very often in recent literature, up to now, very few attempts have been made in North-America or Europe to provide astronaut candidates or spacecrew members with some kind of psychological training. As a first attempt in this field, a psychological training program for science astronauts is described, which has been developed by the German Aerospace Research Establishment and performed as part of the mission-independent biomedical training of the German astronauts' team. In contrast to other training concepts, this training program focused not only on skills needed to cope with psychosocial issues regarding long-term stays in space, but also on skills needed to cope with the different demands during the long pre-mission phase. Topics covered in the training were "Communication and Cooperation", "Stress-Management", "Coping with Operational Demands", "Effective Problem Solving in Groups", and "Problem-Oriented Team Supervision".

Adaptation, Psychological↗
PubMed1986

Flupentixolhydrochloride in low dosages: effects on perceptual and psychomotor performance in emotionally stable and emotionally labile healthy subjects.

Effects of flupentixol on performance were evaluated in a double-blind study with 107 healthy male subjects. Experimental factors were dosage (0, 1, and 2 mg Fluanxol 0.5/day), the trait variable 'neuroticism' (high vs. low score on a questionnaire scale), and time of measurement (before and after 4 days of treatment). Drug effects were measured by means of seven paper-and-pencil tests and eight apparatus tests covering the following cognitive functions: endurance in attention, spacial orientation, flexibility and speed of closure, perceptual speed, response speed, psychomotor coordination, knowledge of traffic rules, and basic motoric tempo. Univariate and multivariate ANOVAs disclosed that flupentixol has detrimental effects on perceptual and psychomotor functions, in particular when administered in a dosage of 2 mg/day. These treatment effects did not interact with the trait variable neuroticism. Nevertheless, there were substantial differences between emotionally stable and emotionally labile subjects in both absolute performance level and change of performance over time.

Adult↗
PubMed1986

[Subjective findings in emotionally stable and labile subjects following oral application of flupenthixol in small doses].

The mood-changing effects of flupentixol (Fluanxol 0.5 mg) were evaluated in a double-blind study with 107 healthy male subjects. Experimental factors were dosage (0, 1 and 2 mg flupentixol/day), time of measurement (before, during, and after 4 days of treatment), and the trait variable "neuroticism" (high vs. low score on a questionnaire scale). Drug effects were measured by means of rating scales and symptom checklists. Statistical analyses revealed that state anxiety and bodily symptoms associated with depressive states were diminished by flupentixol. Moreover, emotionally labile subjects reported an impairment of vigilance under drug treatment. Placebo effects proved to be more substantiated in the group of emotionally stabile subjects than in the group of emotionally labile subjects.

Adult↗
PubMed1985

Delineation of pharmacopsychological effects by means of endogenous event-related brain potentials: an exemplification with flupentixol.

A new experimental paradigm for studying cognitive functions by means of endogenous event-related brain potentials is presented. The paradigm has the following characteristics: (1) subcomponents of 'P300' (P3a, P3b, positive slow wave) and subcomponents of 'CNV' (early and late wave) are separated in time; (2) probability effects known to work on P300 subcomponents are completely under experimental control; and (3) psychologically defined antecedent conditions which affect particular endogenous components can be manipulated precisely and independently of each other. The usefulness of the paradigm for monitoring pharmacopsychological effects on cognitive functions is exemplified by means of flupentixol (Fluanxol 0.5). Reliable drug effects were observed with a dosage of 2 mg/day after 4 days of treatment. The results can be taken as evidence that flupentixol has an impairing effect on human information processing resources; in particular functions related to motor preparation, perceptual analysis, and memory retrieval are affected.

Adult↗
PubMed1981

Principal components and varimax-rotated components in event-related potential research: some remarks on their interpretation.

Some properties of principal components analysis (PCA) and simple structure rotation, which are relevant to the study of event-related potentials (ERPs), were examined both in theory and with simulated data. The analysis casts some doubt on whether it is useful and desirable to rotate the loading pattern of a PCA of ERPs to simple structure. The evidence presented is more in favour of the unrotated solution. In particular we were able to demonstrate with simulated data that a solution rotated to simple structure may lead to false conclusions about the functional independence of ERP peaks. Beyond this, the more general question is asked of whether principal components should be accepted as basic waveforms, i.e. as physiologically meaningful entities which, for example, represent different ERP generators.

Contingent Negative Variation↗