Etude de la plasticité du système neuromusculaire chez le rat soumis à un épisode d'hypodynamie-hypokinésie

La microgravite se caracterise par une reduction des activites sensorimotrices. Elle induit une perte de masse et de force musculaire se manifestant sur les muscles lents posturaux. Ces effets sont bien connus. Par contre, il y a peu de donnees sur les modifications fonctionnelles du systeme neuromusculaire. L'objectif de ce travail a ete de determiner si la microgravite induit le developpement d'une plasticite de ce systeme. L'hypodynamie-hypokinesie (hh) des muscles des membres posterieurs est obtenue par l'utilisation du modele du rat suspendu, modele terrestre de microgravite simulee. Dans une premiere partie, l'etude de la plasticite motrice induite par 14 jours d'hh a ete realisee en etudiant l'activite electromyographique de deux muscles extenseurs de la cheville, lors de la locomotion sur tapis roulant. Apres hh, le patron locomoteur est modifie de facon differentielle. Ceci traduit des modifications de la commande nerveuse de ces deux muscles. Dans une seconde partie, la plasticite nerveuse sensorielle a ete abordee par trois etudes (cartographie corticale, marquage de la proteine fos, potentiels evoques). Nos travaux mettent en evidence une reorganisation des cartes sensorielles, une augmentation du niveau d'activation des cellules spinales et corticales (marquage fos augmente) et des modifications de la transmission des messages nerveux afferents. L'existence d'une plasticite du systeme neuromusculaire apres un episode d'hh est ainsi demontree. Les resultats obtenus peuvent servir d'elements d'interpretation pour expliquer les modifications d'ordre fonctionnel (troubles de la locomotion) observes chez l'homme apres un sejour en microgravite reelle.LILLE1-BU (590092102) / SudocSudocFranceF

EValuation of Anxiety in situation of short-term microgravity (EVA-0G): sensitivity of cognitive parameters

International audienc

EValuation of Anxiety in situation of short-term microgravity (EVA-0G): sensitivity of psychological parameters

International audienceIntroduction. Spatial environments expose astronauts to numerous stressors (physical, physiological and psychological). In this context, modifications of affective states may affect astronauts' performances. The aim of our project "EVA-0G" is to identify the most sensitive parameter (psychological, cognitive and physiological) of emotional changes in situation of microgravity. Thus, this present study used to parabolic flight in order to assess the influence of anxiogenic situation in microgravity on psychological parameters. Methods. Experiments were performed during parabolic flights. Data are collected during parabolas (0G) and horizontal flight (1G). 12 male subjects have been recruited. In our study, there are two conditions: control and anxiogenic. Anxiogenic condition was created by the expectation of a stressor which is represented by white noises (95dB, 50 ms). Psychological parameters were assessed by questionnaires. Self-Assessment Manikin (SAM)(Bradley et Lang, 1994) was used to assess valence and arousal which are two dimensions of emotions. State-Trait Anxiety Inventory (STAI-YA) (Spielberger et al., 1983) and Visual Analogic Scales (VAS) were used to assess state-anxiety. All these questionnaires are filled out in the different experimental conditions (1G/0G, control/anxiogenic). SAM and VAS were performed during the flight. STAI-YA, which lasts longer, was performed at the end of the flight. Results. Results of VAS confirm the anxiogenic effect of our stressor in 1G (p<0.05) and 0G (p = 0.056). Compared to 1G, valence measured by SAM increases in 0G in control (p<0.05) and anxiogenic (p<0.05) conditions. No difference between the experimental conditions was observed in STAI-YA and level of arousal. Discussion. In agreement with literature, results of VAS suggests that exposure to the stressor (Hillman et al., 2005) and/or expectation of this stressor (Droit-Volet et al., 2010) increases state-anxiety in both 1G and 0G, despite the pleasant effect of 0G. Nevertheless, there are no differences between the experimental conditions in STAI-YA and level of arousal, which are two parameters related to the anxiogenic situation. In this specific context, all these results suggest that the subjects are able to detect the anxiogenic situation despite the pleasant effect of this experience. Only state-anxiety measured during the flight is sensitive to the anxiogenic situation. This suggests that questionnaires about state-anxiety filled out after the flight are not enough sensitive to the affective change related to anxiogenic situation in microgravity

Moderate anxiety modifies the electromyographic activity of a forearm muscle during a time-reaction task in women

International audienc

EValuation of Anxiety in situation of short-term microgravity (EVA-0G): sensitivity of psychological parameters

International audienceIntroduction. Spatial environments expose astronauts to numerous stressors (physical, physiological and psychological). In this context, modifications of affective states may affect astronauts' performances. The aim of our project "EVA-0G" is to identify the most sensitive parameter (psychological, cognitive and physiological) of emotional changes in situation of microgravity. Thus, this present study used to parabolic flight in order to assess the influence of anxiogenic situation in microgravity on psychological parameters. Methods. Experiments were performed during parabolic flights. Data are collected during parabolas (0G) and horizontal flight (1G). 12 male subjects have been recruited. In our study, there are two conditions: control and anxiogenic. Anxiogenic condition was created by the expectation of a stressor which is represented by white noises (95dB, 50 ms). Psychological parameters were assessed by questionnaires. Self-Assessment Manikin (SAM)(Bradley et Lang, 1994) was used to assess valence and arousal which are two dimensions of emotions. State-Trait Anxiety Inventory (STAI-YA) (Spielberger et al., 1983) and Visual Analogic Scales (VAS) were used to assess state-anxiety. All these questionnaires are filled out in the different experimental conditions (1G/0G, control/anxiogenic). SAM and VAS were performed during the flight. STAI-YA, which lasts longer, was performed at the end of the flight. Results. Results of VAS confirm the anxiogenic effect of our stressor in 1G (p<0.05) and 0G (p = 0.056). Compared to 1G, valence measured by SAM increases in 0G in control (p<0.05) and anxiogenic (p<0.05) conditions. No difference between the experimental conditions was observed in STAI-YA and level of arousal. Discussion. In agreement with literature, results of VAS suggests that exposure to the stressor (Hillman et al., 2005) and/or expectation of this stressor (Droit-Volet et al., 2010) increases state-anxiety in both 1G and 0G, despite the pleasant effect of 0G. Nevertheless, there are no differences between the experimental conditions in STAI-YA and level of arousal, which are two parameters related to the anxiogenic situation. In this specific context, all these results suggest that the subjects are able to detect the anxiogenic situation despite the pleasant effect of this experience. Only state-anxiety measured during the flight is sensitive to the anxiogenic situation. This suggests that questionnaires about state-anxiety filled out after the flight are not enough sensitive to the affective change related to anxiogenic situation in microgravity

EValuation of Anxiety in situation of short-term microgravity (EVA-0G): sensitivity of cognitive parameters

International audienc

Hindlimb unloading affects cortical motor maps and decreases corticospinal excitability

International audienc

Electromyographic Activity of Rat Ankle Extensors During Treadmill Locomotion after Hindlimb Unloading

The aim of this work was to study the electromyographic characteristics of two ankle extensors during treadmill locomotion after hindlimb unloading. The studied muscles were the soleus which contains mainly slow fibres, and three parts (red, mixed and white) of the heterogeneous gastrocnemius. Our results showed that the cycle duration was significantly increased (+26%) after 14 days of unloading; the burst duration was increased in the soleus (+18%) and in the red gastrocnemius (+20%). The mean EMG (burst area divided by burst duration) was decreased when treadmill speed was increased in the soleus (-11%) and the red part (-5%) of the gastrocnemius after unloading; in contrast, it was greatly increased in the white part (+46%). These data suggest that hindlimb unloading shifts the normal speedrelated increase in muscle effort from the red to the white compartment of the muscle

The time course of autonomic parameters and muscle tension during recovery following a moderate cognitive stressor: Dependency on trait anxiety level

International audienc

Monitoring Mold growth and VOC Emissions from Wood Wool Insulations under Unfavorable Hygrothermal Conditions

Mold growth on indoor surfaces can lead to severe human health effects. The presence of bio-based surfaces under high humidity conditions is expected to favor its development. This study used a custom-built wall at a 1:1 scale mimicking the building structure of real walls of a French public building containing wood wool as a bio-sourced insulation material. The wall was placed at ambient temperature and relative humidity of 70±5% in order not only to characterize mold development, but also Volatile Organic Compounds (VOCs) emissions. Moreover, a 60 x 60 cm piece of the wood wool was inoculated with about 700 CFU/cm2 of the fungus Aspergillus niger to evaluate the proliferation of micro-organisms under these conditions and eventually the emission of microbial Volatile Organic Compounds (mVOCs). The surface emission rates (ER) of Total Volatile Organic Compounds (TVOCs) and mVOCs were thus measured from the inoculated and non-inoculated surfaces. No mold development was observed by the naked eye on the inoculated or on the non-inoculated surface of the wood wool after one month and this was confirmed by counting the CFU number. Only four mVOCs were detected from both surfaces with a low ER of less than 1 μg m-2 h-1. The ER of TVOCs was 90.3 μg m-2 h-1 from the non-inoculated surface and 71.2 μg m-2 h-1 from the inoculated surface. The obtained results show that the selected hygrothermal conditions are not sufficient for mold development on wood wool and that the detection of mVOCs is not a reliable indicator for microbial growth.publishedVersio