RESUMEN
It has been demonstrated that simulated microgravity (SM) may lead to cognitive dysfunction. However, the underlying mechanism remains unclear. In present study, tail-suspension (30°) rat was employed to explore the effects of 28 days of SM on hippocampus-dependent learning and memory capability and the underlying mechanisms. We found that 28-day tail-suspension rats displayed decline of learning and memory ability in Morris water maze (MWM) test. Using iTRAQ-based proteomics analysis, a total of 4774 proteins were quantified in hippocampus. Of these identified proteins, 147 proteins were differentially expressed between tail-suspension and control group. Further analysis showed these differentially expressed proteins (DEPs) involved in different molecular function categories, and participated in many biological processes. Based on the results of PANTHER pathway analysis and further western blot verification, we observed the expression of glutamate receptor 1 (GluR1) and glutamate receptor 4 (GluR4) which involved in metabotropic glutamate receptor group III pathway and ionotropic glutamate receptor pathway were significantly induced by SM. Moreover, an increased concentration of glutamic acid (Glu) was also found in hippocampus while the concentrations of 5-hydroxytryptamine (5-HT), dopamine (DA), γ-amino acid butyric acid (GABA) and epinephrine (E) were decreased. Our finding confirms that 28-day SM exposure can cause degrading of the spatial learning and memory capability and the possible mechanisms might be related with glutamate excitotoxicity and imbalances in specific neurotransmitters. BIOLOGICAL SIGNIFICANCE: The goal of sending astronauts farther into space and extending the duration of spaceflight missions from months to years will challenge the current capabilities of bioastronautics. The investigation of the physiological and pathological changes induced by spaceflight will be critical in developing countermeasures to ensure astronauts to complete spaceflight mission accurately and effectively and return to earth safely. It has been demonstrated that spaceflight may lead to impairments in cognitive function which is crucial for mission success. Here we show that long-term simulated microgravity, the most potent environment risk factor during spaceflight, impairs the spatial learning and memory of rats and the underlying mechanism may be involved in glutamate excitotoxicity and imbalances in specific neurotransmitters release in hippocampus, which may provide new insight for the countermeasures of cognitive impairment during spaceflight.
Asunto(s)
Hipocampo/fisiopatología , Proteómica/métodos , Memoria Espacial , Simulación de Ingravidez/psicología , Animales , Regulación de la Expresión Génica , Ácido Glutámico/metabolismo , Suspensión Trasera , Hipocampo/química , Hipocampo/metabolismo , Neurotransmisores/análisis , Ratas , Receptores de Glutamato/metabolismoRESUMEN
Accurate evaluation of emergencies is a critical concern in long-duration space flights. Accordingly, we studied the effect of 45 days of - 6° head-down bed rest - a model that simulates the conditions in microgravity environments - on the evaluation of orally reported emergencies. Sixteen male participants listened to corresponding emergency scenarios and assessed the severity of these situations eight times before, during and after bed rest. The results revealed a ' recency effect': compared with emergency descriptions in the order of serious to mild, those framed in the reverse order were judged to be more serious. However, the severity ratings did not vary with time spent in the simulated microgravity environment. These findings are similar to those observed in a regular environment on Earth, indicating that the design principles of information presentation for situations on Earth may also be extended to designs intended for outer space. PRACTITIONER SUMMARY: A recency effect was found in the evaluation of orally reported emergencies under simulated microgravity conditions. The design principles of information presentation for situations on Earth may also be extended to designs intended for outer space.
Asunto(s)
Comunicación , Urgencias Médicas/psicología , Juicio , Simulación de Ingravidez/psicología , Adulto , Inclinación de Cabeza , Humanos , Masculino , Tiempo de Reacción , Factores de Tiempo , Adulto JovenRESUMEN
Successful adaptation to the microgravity environment of space and readaptation to gravity on earth requires recalibration of visual and vestibular signals. Recently, we have shown that adding simulated viewpoint oscillation to visual self-motion displays produces more compelling vection (despite the expected increase in visual-vestibular conflict experienced by stationary observers). Currently, it is unclear what role adaptation to gravity might play in this oscillation-based vection advantage. The vection elicited by optic flow displays simulating either smooth forward motion or forward motion perturbed by viewpoint oscillation was assessed before, during and after microgravity exposure in parabolic flight. During normal 1-g conditions subjects experienced significantly stronger vection for oscillating compared to smooth radial optic flow. The magnitude of this oscillation enhancement was reduced during short-term microgravity exposure, more so for simulated interaural (as opposed to spinal) axis viewpoint oscillation. We also noted a small overall reduction in vection sensitivity post-flight. A supplementary experiment found that 1-g vection responses did not vary significantly across multiple testing sessions. These findings: (i) demonstrate that the oscillation advantage for vection is very stable and repeatable during 1-g conditions and (ii) imply that adaptation or conditioned responses played a role in the post-flight vection reductions. The effects observed in microgravity are discussed in terms of the ecology of terrestrial locomotion and the nature of movement in microgravity.
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Movimientos de la Cabeza/fisiología , Percepción de Movimiento/fisiología , Flujo Optico/fisiología , Estimulación Luminosa/métodos , Simulación de Ingravidez/métodos , Femenino , Humanos , Masculino , Factores de Tiempo , Vestíbulo del Laberinto/fisiología , Ingravidez , Simulación de Ingravidez/psicologíaRESUMEN
OBJECTIVE: To study the influence of 14- day simulated weightlessness on emotional behaviour in rats. METHODS: Sixteen from twenty male SD rats were selected and assigned to a 2-group design: the control group and the tail suspension (TS) group (n = 8). The essay deployed typical methods for assessing emotional activity in the current, including food-intake and body weight variation, open field testing, sucrose preference testing and the evaluation of emotional arousal level to test emotional behavior. RESULTS: 1. After 14- day simulated weightlessness for rats, their food-intake and body weight increase were less than those in the control group. 2. The ability of movement reduced in rats, the number of locomotion was significantly lower than that in the control group (P < 0.05) and the frequency of self-grooming was significantly higher than that in the control group(P <0.01. 3. A higher level of emotionality in TS group was recorded. 4. Sucrose preference was not observed in TS group. CONCLUSION: It demonstrated depression, anxiety and nervous symptom occurred in the TS rats with a certain degree of nervous reaction but no anhedonia.
Asunto(s)
Emociones , Simulación de Ingravidez/psicología , Animales , Masculino , Ratas , Ratas Sprague-DawleyRESUMEN
INTRODUCTION: This study aimed to test the efficacy of an oral-intake Chinese herbal medicine in enhancing the cognitive and emotional functions of individuals in a simulated microgravity condition. The herbal medicine consisted of ingredients that may enhance cognitive and emotional functions in an extreme environment. METHODS: There were 14 healthy male subjects who were randomly assigned to a Chinese medicine (CMG) or a control (CG) group and underwent a 60-d 6 degree head-down bed-rest protocol. Testing was conducted before (Day -3), throughout (Days 3, 7, 20, 40, 57), and after (Days +3, +10) the bedrest protocol. The Arrow Test, Balloon Analog Risk Task (BART), Dual Task, and Affect Grid were administered on all testing days. RESULTS: The CMG demonstrated consistently higher scores on the BART (Days 20 to 40; Mean: CMG, 43.0 to 46.2 and CG, 30.2 to 25.5) and lower levels of arousal on the Affect Grid (Days 7 to 40; Mean: CMG, 6.9 to 6.7 and CG, 8.1 to 8.0) than did the CG. The CMG showed significantly higher performance on the Arrow Test (incompatible condition) at the beginning of the bed-rest period (Day 3 to 7; Mean: 799.5 ms and 763.1 ms, respectively) which was not observed in the CG. DISCUSSIONS: Results suggest that the Chinese herbal medicine may calm subjects' emotions by lowering the arousal level. At the same time, it may have produced positive effects in enhancing advantageous risk-taking and to a lesser extent self-regulatory behaviors (in the early phase).
Asunto(s)
Medicamentos Herbarios Chinos/uso terapéutico , Psicotrópicos/uso terapéutico , Medidas contra la Ingravidez , Simulación de Ingravidez/psicología , Adulto , Atención , Reposo en Cama , Cognición , Toma de Decisiones , Inclinación de Cabeza , Humanos , Masculino , Pruebas Neuropsicológicas , Asunción de Riesgos , Adulto JovenRESUMEN
INTRODUCTION: Executive functions are high-order aspects of cognition heavily dependent upon the prefrontal cortex. Both prefrontal cortex activity and executive function task performance are enhanced by participation in aerobic physical activity, suggesting that a lack of such activity during the bed rest model of prolonged weightlessness might induce executive function deficits. METHODS: Twenty-four healthy males (ages 21-45 yr) undertook 60 d of head-down bed rest (-6 degrees) for the 2nd Berlin Bed Rest Study (BBR2-2). Three executive function tasks (Iowa Gambling Task, working memory, and flanker) and a reaction time task were administered before, during, and after bed rest. RESULTS: Iowa Gambling Task scores were significantly worse during bed rest (1.7 +/- 6.9) than in other sessions (24.3 +/- 7.8). Effects on working memory and flanker task performance were less obvious, requiring practice effects to be considered. Reaction time was significantly slower after bed rest (569 +/- 42 ms) than in earlier tests (529 +/- 45 ms). There was also significantly less intrasubject variability in reaction time after bed rest, consistent with more efficient executive functioning at this stage. DISCUSSION: Our results provide some evidence for a detrimental effect of bed rest on executive functioning. Whether this stems from a lack of aerobic physical activity and/or changes in the prefrontal cortex remains to be determined. Cognitive effects of bed rest could have implications for the planned human exploration of Mars, and for medical and lifestyle conditions with inadequate levels of aerobic physical activity.
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Cognición , Función Ejecutiva , Tiempo de Reacción , Simulación de Ingravidez/psicología , Adulto , Reposo en Cama , Inclinación de Cabeza , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
This study examined the effect of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance. Each of 7 volunteers were maintained for 3 days of head-down and horizontal bed rest in a counter-balanced design. Assessment measures were polysomnographic recordings on the first night and performance on psychophysiological tasks on the second day involving subjective and objective vigilance, P300, simple reaction time tasks, and dual performance tasks. No clear difference in sleep structure was observed between the head-down and horizontal conditions, except for a slight decrease in Stage 4 for head-down. Both subjective and objective daytime vigilance, P300, and the simple RT task showed no statistical difference, although tracking performance on the dual task showed deterioration at 10:00 for the head-down condition. These results suggest that nocturnal sleep, daytime vigilance, and psychophysiological functions were not disturbed in head-down sleep conditions, although there was a mild deterioration of higher attentional function in the morning.
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Inclinación de Cabeza/fisiología , Desempeño Psicomotor/fisiología , Fases del Sueño/fisiología , Vigilia/fisiología , Simulación de Ingravidez/psicología , Adulto , Atención/fisiología , Reposo en Cama , Corteza Cerebral/fisiología , Ritmo Circadiano/fisiología , Potenciales Relacionados con Evento P300/fisiología , Análisis de Fourier , Humanos , Cinestesia/fisiología , Masculino , Polisomnografía , Postura/fisiología , Tiempo de Reacción/fisiología , Procesamiento de Señales Asistido por ComputadorRESUMEN
The processing and storage of visual information concerning the orientation of objects in space is carried out in anisotropic reference frames in which all orientations are not treated equally. The perceptual anisotropies, and the implicit reference frames that they define, are evidenced by the observation of 'oblique effects' in which performance on a given perceptual task is better for horizontally and vertically oriented stimuli. The question remains how the preferred horizontal and vertical reference frames are defined. In these experiments cosmonaut subjects reproduced the remembered orientation of a visual stimulus in 1g (on the ground) and in 0g, both attached to a chair and while free-floating within the International Space Station. Results show that while the remembered orientation of a visual stimulus may be stored in a multimodal reference frame that includes gravity, an egocentric reference is sufficient to elicit the oblique effect when all gravitational and haptic cues are absent.
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Gravitación , Percepción Visual/fisiología , Análisis de Varianza , Señales (Psicología) , Femenino , Humanos , Masculino , Orientación/fisiología , Distorsión de la Percepción/fisiología , Estimulación Luminosa/métodos , Psicofísica , Tiempo de Reacción , Vuelo Espacial , Simulación de Ingravidez/psicologíaRESUMEN
INTRODUCTION: We present the results of a two-experiment study designed to evaluate the neurocognitive and psychological effects of six-degree head-down bedrest and pharmacologic interventions (3,5,3'-triiodothyronine; T3) implemented to enhance the muscle and bone atrophy associated with simulated microgravity. Subsequently, the effects of countermeasures (alendronate and testosterone) administered to retard or reverse these T3 plus bedrest enhanced atrophic changes, were evaluated. Each participant was tested weekly for 5 weeks during Bedrest or non-bedrest (Up) conditions with the Neurobehavioral Evaluation System 2 (NES2), the Symptom Check List 90 Revised (SCL-90-R), and the Coping Responses Inventory (CRI). Resultant data were subjected to repeated measures, between groups analysis of variance testing for all 82 neurocognitive and psychological test measures. RESULTS: In Experiment 1, participants in the Placebo-Bedrest condition performed better on several neurocognitive measures compared to participants in the T3-Up condition. However, participants in the Placebo-Bedrest condition also reported more confusion. In Experiment 2 (countermeasure trials), superior coordination was observed for participants in the Testosterone-T3 condition over those in the Alendronate-T3 condition, but just the opposite for reaction time. Also, testosterone and to a lesser degree, alendronate, were associated with less self-reported emotional distress than T3 plus bedrest alone. CONCLUSION: Triiodothyronine, alendronate, and testosterone each influence participant response to simulated microgravity. Between group differences for significant findings were substantial and averaged 1.62 standard deviations. Although the observed neurocognitive effects likely pose no immediate danger for research participants, the significantly greater level of self-reported psychological symptoms by T3-Placebo and Placebo-Bedrest treated participants is of clinical importance.