Short-term memory effects of an auditory biofeedback on isometric force control: Is there a differential effect as a function of transition trials?

The aim of the present study was to investigate memory effects, force accuracy, and variability during constant isometric force at different force levels, using auditory biofeedback. Two types of transition trials were used: a biofeedback-no biofeedback transition trial and a no biofeedback-biofeedback transition trial. The auditory biofeedback produced a low- or high-pitched sound when participants produced an isometric force lower or higher than required, respectively. To achieve this goal, 16 participants were asked to produce and maintain two different isometric forces (30$\pm$5% and 90N$\pm$5%) during 25s. Constant error and standard deviation of the isometric force were calculated. While accuracy and variability of the isometric force varied according to the transition trial, a drift of the force appeared in the no biofeedback condition. This result suggested that the degradation of information about force output in the no biofeedback condition was provided by a leaky memory buffer which was mainly dependent on the sense of effort. Because this drift remained constant whatever the transition used, this memory buffer seemed to be independent of short-term memory processes.Comment: Human Movement Science (2011) epub ahead of prin

Effets d'une suppl\'eance perceptive visuelle, auditive et tactile sur le contr\^ole des pressions fessi\`eres en position assise

This article presents a study on different informative modalities of a perceptual supplementation device aiming at reducing overpressure at the buttock area. Visual, audio and tactile modalities are analysed and compared with a non-biofeedback session. In conclusion, modalities have a positive and equal effect, but they are not equally judged in term of comfort and disturbance with some other activitie

ÉTUDE DES PROCESSUS PRÉPARATOIRES IMPLIQUÉS DANS LA<br />COORDINATION POSTURE/MOUVEMENT<br /><br />Effets de la période préparatoire sur les ajustements posturaux anticipés

The achievement of a voluntary movement implies setting up preparatory processes which predetermine the effectiveness of the motor behavior. This motor preparation can be dependent on temporal and/or event uncertainties taken into account by the central nervous system in order to carry out the motor act. However, this intentional motor activity is confronted with two apparently contradictory requirements which are on the one hand, the movement of certain body segments directed towards a goal and on the other, the stabilization of the other segments of the body in order to maintain balance. This work aims at crossing the data from the field of mental chronometry with the data from the field of postural control so as to highlight the impact of motor preparation on the coordination between posture and movement. The Research study presented here aims at modifying the quality of motor preparation in order to 1) demonstrate that the coordination posture/movement is dependent on preparatory processes, and 2) evaluate this preparation by looking at the effects of temporal and event uncertainties on the anticipatory postural adjustments (APAs).Thus, this doctoral work supports the idea that the postural component of a posturo-kinetics task is dependent on a preparation. The latter influences it through the various impacts it has on the data processing system.L'accomplissement d'un mouvement volontaire suppose la mise en jeu de processus de préparation qui prédéterminent l'efficacité du comportement moteur. Cette préparation motrice peut être dépendante de l'incertitude temporelle et/ou événementielle prise en compte par le système nerveux central en vue de réaliser l'acte moteur. Cependant, cette activité motrice intentionnelle est confrontée à deux exigences apparemment contradictoires qui sont d'une part, le mouvement de certains segments corporels orientés vers un but et d'autres part la stabilisation des autres segments du corps afin de maintenir l'équilibre. Ce travail vise à croiser les données issues du champ de la chronométrie mentale avec celles issues du domaine du contrôle postural en vue de mettre en évidence l'impact de la préparation motrice sur la coordination entre la posture et le mouvement. La recherche présentée ici a pour ambition de modifier la qualité de la préparation motrice afin 1) de montrer que la coordination posture/mouvement est dépendante des processus de préparation, et 2) d'évaluer cette préparation au regard des effets des différentes incertitudes temporelles et événementielles sur les ajustements posturaux anticipés (APAs).Ainsi, ce travail doctoral supporte l'idée que la composante posturale d'une tâche posturo-cinétique est dépendante d'une certaine préparation. Cette dernière l'influence grâce aux différents impacts dont elle dispose sur le système de traitement de l'information

Sensory supplementation through tongue electrotactile stimulation to preserve head stabilization in space in the absence of vision.

International audiencePURPOSE: To investigate the effectiveness of a head position-based, tongue-placed biofeedback system in providing sensory supplementation to preserve head stability in space in the absence of visual information. METHODS: Nine healthy young men with normal vision and no history of previous motor problems, neck injury, vertigo, neurologic disease, or vestibular impairment voluntarily participated in the experiment. They were asked to stand, their feet placed in a semitandem position, as immobile as possible in two conditions of No Vision and Vision and two conditions of No Biofeedback and Biofeedback. In the Biofeedback condition, subjects executed the postural task using a biofeedback system whose principle consisted of supplying them with additional information about their head orientation/motion with respect to gravitational vertical through electrotactile stimulation of the tongue. A system for the analysis of movement was used to record the head displacements. RESULTS: Without the provision of the biofeedback (No Biofeedback condition), the No Vision condition yielded increased head displacements along the mediolateral axis compared with the Vision condition. Conversely, when biofeedback was available (Biofeedback condition), no significant difference between the No Vision and Vision conditions was observed. CONCLUSIONS: These results suggest that healthy young subjects were able to efficiently use head position-based, tongue-placed biofeedback to suppress the head instability induced by the suppression of vision. Hence the present findings demonstrate the effectiveness of a head position-based, tongue-placed biofeedback in providing sensory supplementation to preserve head stability in space in conditions of absent visual information

Effects of foreperiod duration on anticipatory postural adjustments: determination of an optimal preparation in standing and sitting for a raising arm movement.

The purpose of the present experiment was to examine the motor and postural preparation processes evolving during the foreperiod (known to be optimal at 500 ms in sitting) in a voluntary upper limb movement executed while standing. The foreperiod duration (300, 500, 700 and 900 ms) and the postural conditions (sitting versus standing) were manipulated using a priming procedure. Two types of prime were provided: (1) a prime giving valid information on the side of the raising arm movement to execute, and (2) a prime giving non-valid information (prime opposite to the required side). In a sitting and standing condition, eight normal subjects performed a raising arm movement with a 1 kg load at the level of the wrist. Premotor time and acceleration of arm movement were recorded in the two postural conditions. In the standing condition, anticipatory postural adjustments (APAs) were also quantified using the relative latency of electromyographic (EMG) data and the centre of foot pressure (CoP) displacements. Results (1) showed that the optimal foreperiod duration (i.e., leading to the shortest premotor time) increased as a function of postural conditions (500 versus 700 ms in the sitting and standing conditions, respectively), and (2) emphasized the existence of a temporal modulation in the central organization of the postural and focal commands according to the foreperiod duration

Predictable postural perturbation in premotor and motor components of reaction time.

The aim of the present experiment was to study the central control of posture and movement coordination. Subjects' task was voluntarily to raise their arms in response to a visual signal, this movement generating an unloading in which the weight of the load (0 gm, 1500 gm, 3000 gm, or 4500 gm) was known in advance. Thus, subjects could predict the postural perturbation generated by the unloading. Analysis showed an effect of the unloading conditions: in the 0-gm and 1500-gm conditions, reaction time (RT) was longer than in the 3000-gm and 4500-gm conditions. This decrease in RT was exclusively due to a reduction of the premotor time, confirming the posturokinetic coordination in the programming processes. The implications of the decrease in premotor time with the increase of the perturbation for the posture/movement coordination strategies are also discussed

Etude des processus préparatoires impliqués dans la coordination posture/mouvement (effets de la période préparatoire sur les ajustements posturaux anticipés)

L'accomplissement d'un mouvement volontaire suppose la mise en jeu de processus de préparation qui prédéterminent l'efficacité du comportement moteur. Cette préparation motrice peut être dépendante de l'incertitude temporelle et/ou événementielle prise en compte par le système nerveux central en vue de réaliser l'acte moteur. Cependant, cette activité motrice intentionnelle est confrontée à deux exigences apparemment contradictoires qui sont d'une part, le mouvement de certains segments corporels orientés vers un but et d'autres part la stabilisation des autres segments du corps afin de maintenir l'équilibre. Ce travail vise à croiser les données issues du champ de la chronométrie mentale avec celles issues du domaine du contrôle postural en vue de mettre en évidence l'impact de la préparation motrice sur la coordination entre la posture et le mouvement. La recherche présentée ici a pour ambition de modifier la qualité de la préparation motrice afin 1) de montrer que la coordination posture/mouvement est dépendante des processus de préparation, et 2) d'évaluer cette préparation au regard des effets des différentes incertitudes temporelles et événementielles sur les ajustements posturaux anticipés (APAs). Ainsi, ce travail doctoral supporte l'idée que la composante posturale d'une tâche posturo-cinétique est dépendante d'une certaine préparation. Cette dernière l'influence grâce aux différents impacts dont elle dispose sur le système de traitement de l'information.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

The increased foreperiod duration to attain the neutral optimal preparation from sitting to standing.

The purpose of the present experiment was to investigate the effects of a neutral preparation during the foreperiod on motor and postural programming processes in a voluntary upper limb movement. The foreperiod duration (300, 500, 700 and 900 ms) and the postural condition (sitting vs standing) were manipulated using a neutral preparation (no advanced information during the preparatory signal). Thirteen subjects performed a raising arm movement with 1 kg load at the wrist. Premotor time, latency of the anticipatory postural adjustments and the vertical torque were calculated. A previous experiment showed that the optimal foreperiod duration (i.e. leading to the shortest premotor time) increased from sitting to standing in a selective preparation (Cuisinier et al. in Brain Res Bull 66(2):163-170, 2005). The present experiment replicated this finding in a neutral preparation. It was found that (1) this optimal foreperiod duration still increased from 500 ms in sitting to 700 ms in standing in a neutral preparation, (2) this increased optimal foreperiod duration resulted from a greater level of alertness necessary to control a more constrained posture in standing than in sitting, and (3) the existence of a temporal modulation in the central organization of the postural and focal commands was according to the foreperiod duration