Influence of affective stimuli on leg power output and associated neuromuscular parameters during repeated high intensity cycling exercises

The aim of this study was to examine the impact of emotional eliciting pictures on neuromuscular performance during repetitive supramaximal cycling exercises (RSE). In a randomized order, twelve male participants were asked to perform five 6-s cycle sprints (interspaced by 24 s of recovery) on a cycle ergometer in front of neutral, pleasant or unpleasant pictures. During each RSE, mean power output (MPO) and electromyographic activity [root mean square (RMS) and median frequency (MF)] of the vastus lateralis and vastus medialis muscles were analyzed. Neuromuscular efficiency (NME) was calculated as the ratio of MPO to RMS. Higher RMS (232.17 ± 1.17 vs . 201.90 ± 0.47 μV) and MF (68.56 ± 1.78 vs . 64.18 ± 2.17 Hz) were obtained in pleasant compared to unpleasant conditions (p < 0.05). This emotional effect persisted from the first to the last sprint. Higher MPO was obtained in pleasant than in unpleasant conditions (690.65 ± 38.23 vs . 656.73 ± 35.95 W, p < 0.05). However, this emotional effect on MPO was observed only for the two first sprints. NME decreased from the third sprint (p < 0.05), which indicated the occurrence of peripheral fatigue after the two first sprints. These results suggested that, compared with unpleasant pictures, pleasant ones increased the neuromuscular performance during RSE. Moreover, the disappearance of the beneficial effect of pleasant emotion on mechanical output from the third sprint appears to be due to peripheral fatigue

All-optical free-space routing of upconverted light by metasurfaces via nonlinear interferometry

All-optical modulation yields the promise of high-speed information processing. In this frame, metasurfaces are rapidly gaining traction as ultrathin multifunctional platforms for light management. Among the featured functionalities, they enable light wavefront manipulation and, more recently, demonstrated the ability to perform light-by-light manipulation through nonlinear optical processes. Here, by employing a nonlinear periodic metasurface, we demonstrate all-optical routing of telecom photons upconverted to the visible range. This is achieved via the interference between two frequency-degenerate upconversion processes, namely third-harmonic and sum-frequency generation, stemming from the interaction of a pump pulse with its frequency-doubled replica. By tuning the relative phase and polarization between these two pump beams, and concurrently engineering the nonlinear emission of the individual elements of the metasurfaces (meta-atoms) along with its pitch, we route the upconverted signal among the diffraction orders of the metasurface with a modulation efficiency up to 90%. Thanks to the phase control and the ultrafast dynamics of the underlying nonlinear processes, free-space all-optical routing could be potentially performed at rates close to the employed optical frequencies divided by the quality factor of the optical resonances at play. Our approach adds a further twist to optical interferometry, which is a key-enabling technique in a wide range of applications, such as homodyne detection, radar interferometry, LiDAR technology, gravitational waves detection, and molecular photometry. In particular, the nonlinear character of light upconversion combined with phase sensitivity is extremely appealing for enhanced imaging and biosensing.Comment: 18 pages, 6 figure

Role of gait initiation in the analysis of human behaviour

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La signature émotionnelle d’un mouvement volontaire complexe : l’initiation de la marche

International audienceL’initiation de la marche est un mouvement volontaire de l’ensemble du corps réalisé au quotidien. En effet, ce mouvement assure la transition entre la posture debout (en double appui) et le cycle de marche (débutant au décollement du pied initiant la marche). Il implique une coordination complexe entre la posture et le mouvement et possède un double objectif : la création des conditions nécessaires pour la progression, i.e. se déplacer vers l’avant et atteindre une vitesse de marche donnée, tout en assurant la stabilité posturale, i.e. passer successivement de phases en double et simple appui sans tomber. Notre objectif est de montrer que cette coordination posture-mouvement possède une signature émotionnelle : sa performance dépend du traitement de l’information visuelle émotionnelle présente dans l’environnement du sujet

Pratiquer dans un contexte plaisant pour une activité physique durable

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Construction d un modèle intégré (interactions entre émotion et production d un mouvement volontaire de l ensemble du corps)

L objectif de ce travail était d étudier les interactions entre émotion, cognition et mouvement sous l angle de la dimension émotionnelle de l approche-évitement intégrée au processus de production d un mouvement volontaire de l ensemble du corps : la sélection et l élaboration des programmes moteurs de l initiation de la marche. Pour cela, un modèle intégratif a été construit de manière à articuler quatre théories : celles relatives au contrôle cognitif du mouvement, à l organisation biphasique des émotions, à la gestion du conflit et à la charge perceptive. Les résultats obtenus permettent tout d abord de conceptualiser l initiation de la marche comme un mouvement à valence émotionnelle : la production de ce mouvement est dépendante du contexte émotionnel (plaisant/déplaisant) dans lequel il est réalisé. De plus, cette dépendance est d autant plus importante que l influence des émotions sur le temps de réaction et l amplitude de la réponse motrice sur l axe médio-latéral n a pu être modulée par la mise en place de processus cognitif (haut niveau de contrôle cognitif) et perceptif (charge perceptive élevée). Or, dans le cadre de tâches de pression sur un bouton de clavier d ordinateur, ces processus sont utilisés pour moduler les interactions entre émotions et mouvement. En revanche, le contrôle postural sur l axe antéropostérieur, axe de la direction d approche-évitement, semble être spécifique dans la mesure où l influence des émotions sur son amplitude a pu être modulée (diminuée) par la mise en œuvre de ces mêmes processus cognitif et perceptif.The purpose of this work was to study the interactions between emotion, cognition and movement in terms of approach-avoidance emotional dimension integrated on the production of a voluntary whole body movement: the preparation and the selection of gait initiation s motor programs. An integrative model has been built in order to articulate four theories: those relating to the cognitive control of the movement, to the biphasic organisation of emotion, to the conflict monitoring and to the perceptual load. First, results provide new insights about gait initiation: this movement has an emotional significance in terms of its approach-avoidance direction. This movement production is dependent on the emotional context (pleasant/unpleasant) in which there is provided. Moreover, this dependance is even more important than emotional influence on reaction time and on the magnitude of the motor response of the medio-lateral axis could not be modulated by the implementation of cognitive (high level of cognitive control) and perceptual (high level of perceptual load) processes. In typical button press tasks, these processes are used to modulate the interactions between emotion and movement. In addition, results obtained on the approach-movement direction demonstrated a specificity of the anteroposterior postural control, since the emotional influence on its magnitude has been modulated (attenuated) by these same cognitive and perceptual processes.NANTERRE-BU PARIS10 (920502102) / SudocSudocFranceF

Interaction between emotion and postural control associated with forward or backward step initiation

International audienceThis study investigated the impact of emotion-eliciting images on anticipatory postural adjustments (APAs) associated to forward or backward step initiation. Eighteen healthy young women initiated the two kinds of steps in two conditions: 1) if they judged the image as pleasant or unpleasant, respectively (i.e. congruent condition) and 2) if they judged the image as unpleasant or pleasant, respectively (i.e. incongruent condition). Nine participants performed the congruent condition first while the others performed it in second. The results show that the emotional effect (i.e. the difference between the congruent and incongruent conditions) on APAs associated to forward step only differs according to the axis (anterior-posterior, medio-lateral) that is considered, suggesting a specific emotional component of postural stability

Influence d'un conflit émotionnel sur l'initiation de la marche

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Gait Initiation Is Affected during Emotional Conflict

International audienceThe present study examined whether emotion eliciting images affected motor output when a whole body movement was concerned: gait initiation. From a standing posture, 15 young adults were instructed to initiate gait (several steps) towards pleasant or unpleasant images corresponding to a congruent (CO) or an incongruent (IC) task. The movement was performed as soon as possible after the onset of images, using a paradigm of go/nogo. Because an emotional conflict had to be overcome in IC trials, we hypothesized that the longest reaction times and lowest amplitude of early postural adjustments were found during IC trials, as compared to CO trials. We also anticipated that conflict resolution would be improved if the previous trial was IC rather than CO, as previously reported in a typical press button task. Results demonstrated longer reaction times in IC than CO trials revealing that emotional conflict resolution interfered with cognitive resources involved in motor planning. Although the peak of forward velocity reached by the centre of body mass at the end of the first step and length of this step were similar between CO and IC trials, the amplitude of early postural modifications was reduced in IC trials. All together, these findings provided supporting evidence that a defensive response, possibly a freezing-like behaviour, was implemented during IC trials, but in a transient manner. Furthermore, conflict resolution was improved when the previous trial was IC rather than CO in terms of amplitude of early postural response, but not reaction time

Characterizing the Emotional Context Induced by Music Listening and its Effects on Gait Initiation: Exploiting Physiological and Biomechanical Data

International audienceThe ability to initiate gait involves a complex coordination between posture and movement, known as anticipatory postural adjustments (APAs). The emotional context in which gait initiation occurs can impact several spatio-temporal parameters, particularly the duration of APAs. While previous studies have used biologically relevant stimuli to induce emotions, such as images of pleasant or unpleasant scenes, to the best of our knowledge, the impact of the emotional context induced by music on gait initiation has not been explored yet. This paper presents a new dataset collected to study this impact. Objective biomechanical and physiological data were collected from participants during and after music listening, and subjective emotional responses were assessed using questionnaires. We also focused on two factors, liking judgment and familiarity, known to modulate emotions. Our preliminary analyses shows the impact of the emotional context induced by music on gait initiation, and confirms the strong importance of liking judgment and familiarity on the emotional context