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International audience; Simultaneous execution of motor and cognitive tasks is embedded in the daily life of children. 53 children of 7-12 years and 22 adults (study 1), 20 healthy children and 20 children of 7-12 years with cerebral palsy (study 2) performed a Stroop-animal task simultaneously with a standing or a walking task in order to determine the attentional demand of postural control and locomotion. Dual-task cost decreased with advancing age in healthy children during balance. CP and healthy children were similarly affected by dual-task constraints during standing and walking. Children with diplegia were more affected by the DT during the postural task than children with hemiplegia. We found that adults could benefit from dual-tasking for standing. The integrated model of task prioritization might explain our results regarding postural reserve of each population.

ispartof: Annals of Physical and Rehabilitation Medicine vol:58 issue:6 pages:354-356 ispartof: location:Netherlands status: published

Objective The purpose of this study was to determine the influence of age, segmental acceleration and sensory context on anticipatory postural adjustments (APAs) in a forward leg raising task. Methods Three groups of 11 children, aged 8, 10 and 12, and 12 adults, aged 20 to 26, were instructed to perform this movement at maximal ( MAXIMAL ) and sub-maximal segmental accelerations and in normal ( CONTROL ), no vision ( NV ) and perturbed proprioception conditions ( VIB ). The generation and calibration of APAs were examined through the centre of foot pressure displacements: The onset, duration and amplitude of APAs were particularly explored. The EMG activity of the tibialis anterior (TA stance ) and gastrocnemius medialis (G stance ) of the stance leg was also recorded. Results Two phases were clearly identified on the ML axis: A thrust and an unloading phase. Effect of age : At 8 and 10, (1) the unloading duration was shorter, and (2) the onset of APAs on the ML axis appeared later than in 12-year-old children and in adults. Effect of the segmental acceleration : (1) a greater amplitude of the thrust and unloading phases, (2) a shorter unloading duration, and (3) a later onset of ML APAs and of the TA stance activity were observed at maximal acceleration in all groups. Effect of the sensory context : No difference was found between the CONTROL and NV conditions. When the proprioceptive feedback was altered, (1) the thrust and unloading durations increased, and (2) the onset of the APAs on the ML axis occurred earlier. Conclusion All children exhibited an anticipatory behaviour, but the adults’ behaviour was reached at 12 only. Our results also indicated a change in the generation and calibration of APAs in the VIB condition, suggesting that proprioceptive information is essential for both dimensions of the APAs. Significance The development of the APAs was not related to the segmental acceleration and to the sensory context of the forthcoming movement in children aged 8–12. It is very likely that the participants built up an internal representation of this movement.

Partant du constat de la place tres marginale des lettres medievales dans le secondaire en France et particulierement au lycee, nous nous proposons de montrer le paradoxe d’une telle situation, etant donne le profit culturel et didactique que representent les lettres medievales pour l’enseignement de la litterature et pour l’enseignement en general. En effet, les lettres medievales seraient a meme de developper de nombreuses competences litteraires mais aussi de nombreux savoirs culturels au lycee, tout en posant la question des valeurs esthetiques, ethiques, qui definissent une societe. Une fois ces enjeux repertories, nous nous interrogeons sur les obstacles a leur enseignement dans le secondaire depuis les annees 1970, qui semblent desormais s’aplanir au regard d’autres phenomenes culturels susceptibles de favoriser leur presence dans l’enseignement secondaire. Mais surtout, la litterature medievale, par son alterite, ne peut que conduire a un renouvellement de l’approche des textes en classe ; ainsi, elle presente tout particulierement des affinites electives avec les demarches preconisees depuis quelques decennies par la recherche en didactique de la litterature, fondees sur le concept de lecture litteraire. Cette reflexion se termine alors sur quelques modestes propositions pour une veritable place des lettres medievales dans l’enseignement secondaire.

On clearing fields, Ntumu farmers in southern Cameroon leave some large trees. The seed rain beneath 30 such remnant trees (12 species) was compared with that 10 m away from the edges of their crowns. Of a total of 39 765 seeds recorded in 90 seed traps over 2 y, 73.6% were of species different from the tree associated with each set of traps (‘foreign seed rain’). Seed rain included 100 morphospecies, two-thirds of which possessed endozoochorous seeds. Seeds of the pioneer tree Musanga cecropioides accounted for 71.4% of total foreign seed rain; seeds of this and other animal-dispersed species accounted for 94.5% of the total. Seed rain was 25 times higher beneath remnant trees than 10 m away. Mean species richness of monthly seed rain was three times higher beneath remnant trees than 10 m away. Both fleshy-fruited and wind-dispersed species of remnant trees attracted seed-dispersing animals which greatly enhanced the seed rain; attraction thus did not depend solely on presence of fleshy fruits. Seed rain was lower when human activity in fields was intense and increased during the period of growth of the last crops, which were not usually weeded. Heavy seed rain just before fallow may contribute significantly to regeneration, as does the presence of remnant trees.

International audience; Obese people suffer from postural deficits and are more subject to falls than their lean counterpart. To improve prevention and post-fall rehabilitation programs, it seems important to better understand the posturo-kinetic disorders in daily life situations by determining the contribution of some key factors, mainly morphological characteristics and physical activity level, in the apparition of these disorders. Twelve severe android obese and eight healthy non obese adults performed a reaching task mobilizing the whole body. To further determine the origin of the postural and motor behavior differences, non obese individuals also performed an experimental session with additional constraints which simulated some of the obese morphological characteristics. Impact of the sedentary lifestyle was also studied by dissociation of the obese in two subgroups: physically " active " and physically " inactive ". Movement kinetics and kinematics were characterized with an optoelectronic system synchronized to a force platform. The mechanical equilibrium pattern was evaluated through the displacements of the Centre of Mass (CoM) and the centre of foot pressure within the Base of Support (BoS). Results showed that obesity decreased movement speed (≈-23%, p

Several changes in the human sensory systems, like presbycusis or presbyopia, are well-known to occur with physiological ageing. A similar change is likely to occur in proprioception, too, but there are strong and unexplained discrepancies in the literature. It was proposed that assessment of the attentional cost of proprioceptive control could provide information able to unify these previous studies. To this aim, 15 young adults and 15 older adults performed a position matching task in single and dual-task paradigms with different difficulty levels of the secondary task (congruent and incongruent Stroop-type tasks) to assess presumed age-related deficits in proprioceptive control. Results showed that proprioceptive control was as accurate and as consistent in older as in young adults for a single proprioceptive task. However, performing a secondary cognitive task and increasing the difficulty of this secondary task evidenced both a decreased matching performance and/or an increased attentional cost of proprioceptive control in older adults as compared to young ones. These results advocated for an impaired proprioception in physiological ageing. ispartof: Age vol:34 issue:5 pages:1179-94 ispartof: location:Netherlands status: published

International audience; BACKGROUND: In human pathology, the "creeping fat" (CF) of the mesentery is unique to Crohn's disease (CD). CF is usually referred to as an ectopic extension of mesenteric adipose tissue (MAT). However, since no animal model developing CF has ever been established, very little is known about this type of fat-depot expansion and its role in the development of the disease. METHODS: We developed and standardized an experimental protocol in mice that reproducibly induces CF development when a severe colonic inflammation is obtained by intracolonic instillation of DNBS. RESULTS: Macro-microscopic observations revealed a fatty appearance of CF. Yet when compared to MAT from the same animals, CF contains very little triglycerides, few adipocytes, and we observed a very low expression and protein levels of both adipose markers (hormone-sensitive lipase, perilipin) and adipocytokines (leptin, adiponectin). The decreased expression of perilipin in CF was also observed by immunohistochemistry. Conversely, the expression of proinflammatory and fibrous markers (Pref-1) was much higher in CF than in MAT. These observations were fully consistent with those made on CF recovered from five CD patients and compared with subcutaneous and mesenteric fat from the same patients. CONCLUSIONS: Altogether, this work reports an original experimental mice model of CF. In this model we establish for the first time that CF only occurs in severe colonic inflammation and shows an inflammatory, fibrous but not an adipose pattern.

International audience; How sensory organization for postural control matures in children is not clear at this time. The present study examined, in children aged 7 to 11 and in adults, the postural control modifications in quiet standing when somatosensory inputs from the ankle were disturbed. Since the reweighting of sensory inputs is not mature before 10, we hypothesized that postural stability was more affected in children than in adults when somatosensory inputs were altered and that this postural instability decreased as age increased during childhood. 37 children aged 7 to 11 years and 9 adults participated in the experiments. The postural task was a semi-tandem position with the right foot in front of the left one. Postural performance was measured by means of a force platform. Two experimental conditions were presented to the participants to maintain quiet standing: With or without altered somatosensory inputs (i.e., with or without ankles vibration). Results showed that postural stability--and thus how the reweighting process of the visual/somatosensory inputs matured--increased non-monotonically between 7 years of age and adult age: There was a linear improvement of postural stability from 7 to 10, followed by a more steady behaviour between 10 and 11 and then postural stability increased to reach the adults' level of performance.

International audience; In the present study we aimed to determine the attentional cost of postural control during adolescence by studying the influence of a cognitive task on concurrent postural control. 38 teenagers aged 12 to 17 years and 13 young adults (mean age=26.1) stood barefoot on a force platform in a semi-tandem position. A dual-task paradigm consisted of performing a Stroop or a COUNTING BACKWARD task while simultaneously standing quietly on a firm or foam support surface. Different centre of pressure (CoP) measures were calculated (90% confidence ellipse area, mean velocity, root mean square on the antero-posterior (AP) and medio-lateral (ML) axes). The number and percentage of correct responses in the cognitive tasks were also recorded. Our results indicate (1) higher values of surface, ML mean velocity and ML RMS in the COUNTING BACKWARD task in adolescents aged 12 to 15 than in teenagers aged 16 to 17 and in adults, regardless of the complexity of the postural task and, (2) better cognitive performances in the Stroop than in the COUNTING BACKWARD task. The difference in the dual-task performance between the different age groups and particularly the existence of a turning point around 14-15 years of age might be due to 1) difficulties in properly allocating attentional resources to two simultaneous tasks and/or, 2) the inability to manage increased cognitive requests because of a limited information processing capacity in adolescents aged 14-15 years.

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 print

Balance problems are often related to a loss of plantar-sensitivity in elderly people. The purpose of this study was to explore the contribution of plantar cutaneous inputs induced by a spike support surface to the control of stance. Nineteen elderly (mean age 69.0 years, range 62-80) and 19 young adults (mean age 25.9 years, range 21-32) were instructed to stand (standing session) or to walk (walking session) for 5 min with sandals equipped with spike insoles (spike condition). Both sessions also involved a no spike condition in which participants stood or walked for 5 min without these insoles (no spike condition). In all conditions, postural responses were assessed during unperturbed stance and were performed (1) immediately after putting the spike or the no spike insoles, and (2) 5 min after standing or walking with them. Sway parameters, such as centre of foot pressure mean location, surface area, mean speed, root mean square and median frequency on the antero-posterior and medio-lateral axes, were calculated. As postural performances are often related to plantar-surface sensitivity, cutaneous sensitivity threshold was also evaluated with Semmes-Weinstein monofilaments. Although no immediate effect of the spike insoles was found, results indicated that standing or walking for 5 min with sandals equipped with spike insoles led to a significant improvement of quiet standing in the elderly. Balance improvement was also observed in young adults. The results provided evidence that wearing sandals with spike insoles can contribute, at least temporarily, to the improvement of unperturbed stance in elderly people with relatively intact plantar cutaneous sensation. Further research is needed to assess the effects of longer and discontinuous stimulations with spike insoles on postural control.

The present study examined, in children aged 4-11 and in adults, the postural control modifications when attention was oriented voluntary on postural sway. Since (1) there are less attentional resources in children than in adults, (2) the selective attention processing improves with age, i.e., children use a different strategy to focus their attention than adults, and (3) adults' postural stability decreases when attention is focused on postural sway, we hypothesized that postural stability was less affected in children than in adults when attention was focused on postural sway. Fourty four children aged 4- to 11-year-old and 11 adults participated in the experiments. The postural control task was executed in a Romberg position. Two experimental conditions were presented to the subjects, (1) to look at a video on a TV screen without instruction about the posture, and (2) to fixate a cross placed at the center of the TV screen with the instruction to remain as stable as possible. Postural performance was measured by means of a force platform. Results from this study (1) confirmed a non-monotonic improvement of postural stability during the ontogenetic period without reaching the adults' level at the age of 11, (2) suggested that children, aged 4-11, are able to focus their attention on the control of posture, and (3) showed that the automatic control of posture increases postural stability since the age of 4.

The aim of this article is to overview the literature about the development of a gross motor skill in children. This revue focuses on catching and intercepting ball in flight by children from 5 to 13 years old. We analyse the development of cognitive and motor processes and their interaction. After the description of the general mechanisms involved in catching and intercepting, we successively analyse operations involved in : predicting the ball's trajectory, synchronizing the spatio-temporal characteristics of the stimulus with the movement, starting, carrying out and controlling the movement. We also examine the influence of« conative » factors, or factor of personality, on the behavior. We show that these operations are changing as a result of the increase of the information processing capacities across the development., L'objet de cet article consiste en une revue de littérature qui concerne le développement du comportement moteur de l'enfant. Nous avons focalisé cette analyse sur l'exemple des saisies et des interceptions de balle et plus précisément chez l'enfant entre 5 ans et 13 ans. L'intérêt de ce type de tâche réside dans le fait qu'elle exige l'intervention d'opérations cognitives et de mécanismes sensor imoteur s complexes et interdépendants. Après avoir décrit les mécanismes généraux impliqués dans ce type de tâche, nous avons successivement décrit les opérations impliquées dans : l'estimation des caractéristiques cinémati- ques de la trajectoire, la planification du mouvement, les coordinations spatio-temporelles entre le stimulus et le mouvement, l'exécution et le contrôle du geste, les déterminants conatifs du comportement. Nous montrons que l'évolution de ces opérations est sous-tendue par un accroissement des capacités de traitement au cours du développement., Ripoll Hubert, Keller Jean, Olivier Isabelle. Le développement du comportement moteur de l'enfant : l'exemple des saisies et des interceptions de balle. In: Enfance, n°2-3, 1994. pp. 265-284.

Le present article s’efforce de faire une synthese des differents travaux lies au cout attentionnel du controle postural. Dans un contexte de double tâche, la mobilisation des ressources attentionnelles associees au controle de la posture depend de plusieurs facteurs tels que (1) la focalisation attentionnelle volontaire ou automatique sur le controle postural, (2) les informations sensorielles disponibles, (3) la nature et la complexite de la tâche posturale, (4) l’âge, ou encore (5) le niveau d’expertise ou de handicap des sujets. Apres une rapide presentation du paradigme de la double tâche dans le cadre du controle postural, les effets de ces differents facteurs sont analyses plus specifiquement.

International audience; The purpose of the present study was to explore the lasting effects of a tactile sensitivity enhancement induced by spike insoles on the control of stance in the elderly. Healthy elderly subjects (n = 19, mean age = 68.8) and young adults (n = 17, mean age = 24.3) were instructed to stand or to walk for 5 minutes with sandals equipped with spike insoles. Postural control was evaluated four times during unperturbed stance: (1) before putting on the sandals equipped with spike insoles, (2) 5 minutes after standing or walking with them, (3) immediately after placing thin, smooth, and flexible insoles (no spike insoles) into the sandals to avoid the cutaneous contact with the spikes, and (4) after a sitting rest of 5 minutes with the no spike insoles. Sway parameters such as surface area, mean speed and root mean square were recorded. The present results suggest that (1) whatever the session (i.e. standing or walking) and the population, the artificial sensory message elicited by the spikes improved postural sway and, (2) the elderly were particularly perturbed when the tactile sensitivity enhancement device was removed. Whatever the age, the enriched sensory context provided by this tactile sensitivity enhancement device led to a better postural control; its suppression entailed a reweighting of the plantar cutaneous information. The difficulty that the elderly had to adjust the relative contribution of the different inputs probably reflected their poorer central integrative mechanisms for the reconfiguration of the postural set. A reduced peripheral sensitivity may also explain these postural deficits.

The walking acquisition in toddlers involves different complex processes organized into a progressive but non linear way. The child requires several steps to acquire a postural balance, then the propulsion, and the anticipative muscle activation. To understand the gait development of a toddler is fascinating but a very complex work. Indeed, the most of current studies don’t take into account the effects of wearing diapers or clothes on the learning in bipedal locomotion. Regarding step width, which is relatively substantial for the beginner walker, we could wonder it's a strategy in order to improve the supports surface to best control the balance or on the other hand, does wearing diapers cause discomfort in crotch area children, and therefore bring out that postural strategy?Moreover, concerning the gait acquisition, it is known that the child needs well-fitting shoes to avoid any future postural or locomotive pathology. The same approach can be used for clothes. But, we can easily observe that currently most of children clothes are just a copy of adult models in miniature. These clothes don’t consider the morphological, postural and motor features of the beginner walker.The study introduced in this thesis manuscript will not only evaluate the importance of clothing on children walking but also propose possible solution and improvement for the conception of children clothes.Results are related to three studies all regarding children with less than 36 month of walking experience. First study is an analysis of the effect of wearing diaper or trousers on the children walking using spatiotemporal parameters. It has shown a greater influence from trousers than diapers. It has opened the second study. After how many months of experience the effect got the greater influence? Results show influence of trousers starting 3 month of walking but above all from 6 to 18 months. Finally, a prototype of trousers conceived in regards of children characteristics and walking acquisition has been used for around twenty children. Goal of this third study was to evaluate and to understand the importance of clothing on muscular activities of the lower limb. Utilization of the prototype has been conclusive. The muscular co-contractions which highlight the lack of experience in walking are less present when children use the prototype. Discomfort is reduced and walking with the prototype is close to the one performed with underwear., L'acquisition de la marche chez l'enfant comprend différents processus complexes, s'organisant de façon progressive mais non linéaire. Plusieurs étapes sont en effet nécessaires à l'enfant pour acquérir l'équilibre postural, puis la propulsion, ou encore l'activation musculaire anticipatrice. La compréhension du développement de la marche de l'enfant revêt un intérêt passionnant mais d'une grande complexité. Cependant, la plupart des études n'ont pas pris en compte l'effet que pourrait avoir la couche ou la tenue vestimentaire sur l'apprentissage de la locomotion bipédique chez l'enfant. L'écartement latéral des appuis, qui est relativement conséquent chez le marcheur débutant, est-il une stratégie afin d'augmenter sa surface d'appui pour mieux contrôler son équilibre ? Ou bien estce le port de la couche qui provoque une gêne au niveau de l'entrejambe de l'enfant et engendre ou accentue cette stratégie posturale ? Par ailleurs, en ce qui concerne l'acquisition de la marche, il est établit que l'enfant doit être bien chaussé afin d'éviter toute pathologie posturale et/ou locomotrice futures. La même approche peut être abordée pour le vêtement. Or, il est aisé de constater qu'actuellement la plupart des vêtements portés par les enfants ne sont que des répliques miniatures de vêtements d'adultes. Ceuxci ne tiennent pas compte des particularités morphologiques, posturales et motrices du jeune marcheur. Les travaux détaillés dans cette thèse ont pour objectif, non seulement d'évaluer l'impact d'une tenue vestimentaire sur la marche de l'enfant mais également de proposer des pistes de réponses et d'améliorations dans la conception de vêtements d'enfants. Ainsi, ces travaux s'organisent selon trois études portant sur des enfants ayant tous moins de 36 mois d'expérience de marche. La première a consisté en la vérification de l'impact du port d'une couche et/ou d'un pantalon sur la marche de jeunes enfants à partir de l'analyse de paramètres spatio-temporels. Ces travaux révèlent un effet plus prononcé du pantalon que de la couche sur la marche de l'enfant. Puis, nous nous sommes demandés à partir de combien de mois d'expérience de marche cet effet avait-il le plus d'impact. Cette question a fait l'objet de la seconde étude. Enfin, après avoir élaboré un prototype de pantalon prenant en considération les particularités de l'enfant et de l'apprentissage de la marche, celui-ci a été testé sur une vingtaine d'enfants. Cette dernière étude avait pour objectif d'évaluer et de comprendre l'impact de la tenue sur l'activité musculaire du membre inférieur. Les résultats obtenus avec le prototype sont concluants. Les contraintes sont amoindries et la locomotion avec un tel prototype se rapproche de celle observée en sous-vêtement.

ALK1 is a TGF-β family receptor, mainly expressed on endothelial cells. The physiologic and circulating ligand of ALK1, BMP9, was discovered by our laboratory in 2007, which opened opportunities for studying the function of ALK1. The first part of my thesis was on the functional analysis of ALK1 mutants from HHT-2 patients in response to BMP9. This study allowed us to: 1) propose functional haploinsufficiency as a model for HHT-2; 2) develop a diagnostic tool to discriminate pathogenic mutations from rare polymorphisms, based on their BMP9 response; 3) increase our knowledge of important amino acids in ALK1 for the BMP9 response. A second work was on the production of the mature form of BMP9 and of the extracellular domain of ALK1 in order to study the crystallographic structure of the complex. The expression of these proteins and their purification are in optimization phase. Lastly, a third project was on the analysis of the role of BMP9 in angiogenesis in vivo. Neutralization of BMP9 using two strategies induces an increase of the vascular density of the retina in mouse. Mechanism of action is under investigation., ALK1 est un récepteur de la famille du TGF-β, principalement exprimé dans les cellules endothéliales. Le ligand physiologique et circulant d'ALK1, BMP9, a été découvert par notre laboratoire en 2007, ce qui a ouvert des possibilités d'étude de la fonction d'ALK1. La première partie de ma thèse a été consacrée à l'analyse fonctionnelle de mutants d'ALK1, retrouvés sur des patients atteints de la maladie de Rendu-Osler de type 2, en réponse à BMP9. Cette étude a permis de : 1) proposer l'haploinsuffisance fonctionnelle comme modèle de la maladie ; 2) développer un test diagnostique pour discriminer les mutations pathogènes des polymorphismes rares, basé sur leur réponse à BMP9 ; 3) d'avoir une meilleure connaissance des acides aminés d'ALK1 importants dans la réponse à BMP9. Un second travail a consisté en la production de la forme mature de BMP9 et du domaine extracellulaire d'ALK1 en vue de l'étude de la structure cristallographique du complexe. L'expression des protéines et leur purification sont en phase d'optimisation. Enfin, un troisième projet consistait en l'analyse du rôle de BMP9 dans l'angiogenèse in vivo. La neutralisation de BMP9 par deux stratégies distinctes induit une augmentation de la densité vasculaire dans la rétine de la souris. Le mécanisme est en cours d'investigation.

The prevention of falls in elderly is a major focus of medical research. Although the mechanisms underlying the effect of aging on the postural control system are varied and complex, impaired sensory function is likely to be an important contributing factor to the deterioration in postural balance and may increase the likelihood of falling. Age-related loss of cutaneous sensation, in particular, is pervasive, and appears to correlate with impaired postural control. As the feet interface directly with the ground, cutaneous cues provide relevant information about the support surface properties, and about the body position in reference to verticality. The purpose of this study was to explore the effects of a mechanical stimulation of the plantar mechanoreceptors, by means of spikes within the footwear insole, on postural stability. Our results provide evidence that applying a mechanical stimulation reduce, to some extent, postural sway in most of the young adults, the elderly and the patients with diabetic neuropathy. The benefits are not correlated with the cutaneous sensitivity or the initial postural performances of the subject. There was also a significant inter-individual variability. The enriched sensory context provided by the spikes is an original method of stimulation that may be appropriated for subjects with balance problems. This stimulation may reproduce, to some extent, the effects of a massage without requiring a systematic therapeutic intervention. Further research is needed to find the best compromise between the duration, the intensity, the frequency of the stimulation and the comfort of the insoles., La prévention des chutes chez les personnes âgées constitue aujourd'hui un objectif prioritaire en matière de santé publique. Bien que les mécanismes associés au vieillissement soient complexes et variables selon les individus, la détérioration des fonctions sensorielles semble être un des facteurs majeurs de la dégradation du contrôle postural. Cette diminution des performances posturales augmente la probabilité de chute. L'altération de la sensibilité cutanée qui apparaît avec l'âge est, en particulier, à l'origine de problèmes d'équilibre. Compte tenu de leur localisation à l'interface du corps et du support podal, les capteurs tactiles plantaires fournissent des informations très pertinentes sur les oscillations du corps par rapport à la verticale. Dans le cadre de ce travail de thèse, nous nous sommes particulièrement intéressés aux effets d'une stimulation mécanique de la sole plantaire par le port de semelles à picots. Nos travaux ont mis en évidence que ce type de stimulation améliore dans certaines conditions la stabilité posturale chez les jeunes, chez les personnes âgées saines ou atteintes d'une neuropathie diabétique. Les bénéfices observés ne sont ni corrélés à la sensibilité cutanée plantaire, ni aux performances posturales initiales du sujet et varient selon les individus. L'enrichissement du contexte sensoriel apporté par les picots pourrait constituer une méthode de stimulation originale et particulièrement appropriée pour les personnes qui présentent des problèmes d'équilibre. Elle permettrait de reproduire dans une certaine mesure les effets bénéfiques d'un massage de la sole plantaire, ce qui éviterait ainsi l'intervention systématique d'un thérapeute. Les perspectives de ce travail sont nombreuses et nous permettront de déterminer le meilleur compromis en termes de durée, d'intensité, de fréquence de stimulation et de confort afin de pouvoir quantifier plus précisément la stimulation optimale.