Cerebral cortex (New York, N.Y. : 1991), Jan 4, 2016
Proprioceptive processing is important for appropriate motor control, providing error-feedback an... more Proprioceptive processing is important for appropriate motor control, providing error-feedback and internal representation of movement for adjusting the motor command. Although proprioceptive functioning improves during childhood and adolescence, we still have few clues about how the proprioceptive brain network develops. Here, we investigated developmental changes in the functional organization of this network in early adolescents (n = 18, 12 ± 1 years), late adolescents (n = 18, 15 ± 1), and young adults (n = 18, 32 ± 4), by examining task-evoked univariate activity and patterns of functional connectivity (FC) associated with seeds placed in cortical (supramarginal gyrus) and subcortical (dorsal rostral putamen) regions. We found that although the network is already well established in early adolescence both in terms of topology and functioning principles (e.g., long-distance communication and economy in wiring cost), it is still undergoing refinement during adolescence, including...
Différentes études sur la mise en place de stratégies sensorimotrices d'équilibre chez l'enfant s... more Différentes études sur la mise en place de stratégies sensorimotrices d'équilibre chez l'enfant sont rapportées dans cet article. Sur la base de ces résultats expérimentaux et de deux principes fonctionnels (le choix d'un référentiel stable et la maîtrise progressive des degrés de liberté des différentes articulations du corps), Assaiante et Amblard [7]ont récemment proposé un modèle ontogénétique simple et heuristique de la construction des stratégies d'équilibre depuis la naissance jusqu'à l'âge adulte. Ce modèle propose, au cours de quatre périodes successives de l'ontogenèse, l'existence d'un va-et-vient entre deux modes d'organisation temporelle du contrôle de l'équilibre: ascendant ou descendant, auxquels sont associés deux modes de fonctionnement des ensembles de segments corporels: en bloc ou articulé. De récentes études ont pour but de mettre à l'épreuve le degré de généralité des stratégies déjà identifiées et d'étendre la validation du modèle à des situations nouvelles qui impliquent un contrôle de l'équilibre lors des transitions entre les différentes phases du mouvement. Tout en introduisant un enrichissement des caractéristiques propres à chacune des périodes du modèle, les résultats obtenus lors des études développementales relatives au saut et à l'initiation de la marche sont tout à fait cohérents avec les principes fonctionnels qui sont à la base du modèle ontogénétique.A set of experimental studies showing how head-trunk coordination develops during childhood in various locomotor tasks is reported. On the basis of these results and two functional principles (stable reference frame and gradual mastery of the degrees of freedom of the body joints), an ontogenetic model for the sensorimotor organization of balance control in humans is proposed [7]. In this model, we adopt the hypothesis that the two main modes of equilibrium control (ascending vs descending temporal organization) operate alternatively and are associated with either of two modes of head-trunk linkage (“en bloc” vs articulated) during four successive periods in the course of ontogenesis. The advantage of this model is that is heuristic and therefore open to further improvements, including new subdivisions within the proposal periods, the generalization of these balance strategies to most of the posturo-kinetic activities, the comparison between unperturbed natural balance and reactions to transient postural disturbances. These latter proposal are illustrated by the study of new experimental tasks such as hops using one or two feet and initiation of gait. Although they introduce improvements, these new findings are consistent with the functional principles proposed in the previous ontogenetic model.
In the current study, we adopted the hypothesis that the body scheme disturbances occurring durin... more In the current study, we adopted the hypothesis that the body scheme disturbances occurring during adolescence might lead subjects to transiently neglect proprioceptive information and that adolescents might rely more strongly on vision to control their orientation and stabilize their body. To check this point, we asked adolescents 14-15 years to maintain vertical stance while very slow sinusoidal oscillations in the frontal plane were applied to the supporting platform at 0.01 Hz (below the detection threshold of the semicircular canal system) and at 0.06 Hz (above) with the eyes open and closed. Two postural components, orientation and segmental stabilization, were analyzed at the head, shoulder, trunk, and pelvis levels. At the lowest frequency without vision, the performances of adolescents were much less efficient than those of adults. Moreover, this study showed that vision plays a predominant role in adolescents' control of orientation and body stabilization. At 0.06 Hz without vision, a clearcut difference was observed between the strategies used by girls and boys; specifically, the maturation of the segmental stabilization processes was found to be more advanced in girls than in boys. However, no such difference was observed at 0.01 Hz. Lastly, comparisons between the data obtained in adolescents and those previously obtained in young adults (Vaugoyeau, Viel, Amblard, Azulay, & Assaiante, 2008) clearly show that adolescents use different postural strategies and that they are not yet capable of reaching comparable postural performance levels to those observed in adults. Because adolescents were not able to use the proprioceptive information available to improve their postural control, we concluded that they showed a maturational lag in comparison with adults. This suggests that the mechanisms underlying postural control are still maturing during adolescence, which might constitute a transient period of proprioceptive neglect in sensory integration of postural control.
ABSTRACT Agir avec son environnement nécessite d’être conscient de son propre corps. Cette consci... more ABSTRACT Agir avec son environnement nécessite d’être conscient de son propre corps. Cette conscience corporelle est basée sur le schéma corporel qui correspond à la représentation interne du corps en action. La construction du schéma corporel au cours de l’ontogénèse repose grandement sur la proprioception. La maturation des bases cérébrales sous-jacentes à l’intégration proprioceptive reste encore peu connue. C’est autour de 8 ans que l’intégration d’informations proprioceptives au service du contrôle en ligne du mouvement devient plus opérationnelle, signant une maturation progressive des afférences proprioceptives (Contreras-Vidal et al., 2006). De plus, une immaturité du réseau proprioceptif a été observée chez les adolescents, qui se caractérise par une moindre différentiation en comparaison des adultes (Cignetti et al., 2014 ; Assaiante et al., 2014).
Revue de laryngologie - otologie - rhinologie, 2009
The objective of the study was to assess how posture and vocal acoustics are modified when one ne... more The objective of the study was to assess how posture and vocal acoustics are modified when one needs to communicate despite environmental obstacles (i.e. vocal effort performance). 20 healthy young women participated to this study. They had to communicate numbers to a listener. Environmental obstacles were the distance between the subject and the auditor, and the noise. Segmental posture modifications were recorded and analyzed using the numerical infra-red system for movement analysis SMART. Vocal acoustics and electroglottography were also recorded and analyzed using the EVA system. The study showed the presence of objective postural modifications during vocal effort. Their amplitude increased when the environmental obstacles to communications increased, and they anticipated the vocal production. The vocal effort concept and its relation with the posture, the voice and the subject's feeling are reviewed on the basis of these results. Laryngeal effort is not isolated, but belon...
Journal of vestibular research : equilibrium & orientation
The main purpose of this study was to investigate the development of head-trunk coordination duri... more The main purpose of this study was to investigate the development of head-trunk coordination during single hops using one foot or two feet in children of two ages (5.5 to 6 and 7 to 7.5) and adults (n = 6/group). The kinematics of the subjects' hops were analyzed by means of an automatic optical TV-image processor called the ELITE system. The absolute angular dispersion of the head, trunk, and leg about the pitch and the roll axis were measured. Head and trunk pitch and roll anchoring indexes were calculated in order to compare the stabilization of a given segment with respect both to external space and to the underlying anatomical segment. Results were analyzed separately for 3 phases: take-off, flight, and landing. Only the last two phases, flight and landing, are presented in this paper, and the following was found: 1) During flight, under both unipedal and bipedal conditions, head and trunk stabilization in space about the pitch axis occurred in children as well as in adults...
The feeling of illusory movement is considered important in the study of human behavior because i... more The feeling of illusory movement is considered important in the study of human behavior because it is deeply related to motor consciousness. However, the neural basis underlying the illusion of movement remains to be understood. Following optimal vibratory stimulation of muscle tendon, certain subjects experience illusory movements while others do not. In the present fMRI study, we sought to uncover the neural basis of illusory movement awareness by contrasting a posteriori these two types of subjects. Examining fMRI data using leave-one-subject-out general linear models and region of interest analyses, we found that a non-limb-specific associative network, including the opercular part of the right inferior frontal gyrus and the right inferior parietal lobule, was more active in subjects with illusions. On the other hand, levels of activation in other brain areas involved in kinaesthetic processing were rather similar between the two subsamples of subjects. These results suggest that activation of the right inferior frontoparietal areas, once passed a certain threshold, forms the basis of illusory movements. This is consistent with the global neuronal workspace hypothesis that associates conscious processing with surges of frontoparietal activity.
The aim of this study was to explore, during adolescence, alterations in the use of a sensori-mot... more The aim of this study was to explore, during adolescence, alterations in the use of a sensori-motor representation as unveiled by the measurement of anticipatory postural control in a bimanual load-lifting task. We hypothesised that adolescence constitutes a period of refinement of anticipatory postural control due to on-going updates of the body schema and sensori-motor representations. The anticipatory postural control was assessed using a bimanual load-lifting paradigm in which subjects stabilise their left postural forearm, which is supporting an object, while they use their right hand to lift up the object. Kinematics and electromyographic data were recorded in two groups of adolescents (11-13 and 14-16 years of age) and a group of adults. Age and gender effects were tested. During voluntary unloading, the postural forearm stabilisation in adolescents was still different from the adult one, suggesting that further improvement of the postural forearm stabilisation must take place after the age of 16. No differences occur in the two adolescent groups. Moreover, girls presented a better stabilisation of the postural forearm than boys, indicating an earlier refinement of anticipatory postural control. The decrease of activity over postural flexors, which ensure postural stabilisation, appeared later in adolescents with respect to adults. Delayed timing adjustments and increased variability could reflect intense developmental processes underlain by an intense period of CNS maturation during adolescence. We discuss the role of brain maturation in the refinement of sensori-motor representations and the update of body schema.
Cerebral cortex (New York, N.Y. : 1991), Jan 4, 2016
Proprioceptive processing is important for appropriate motor control, providing error-feedback an... more Proprioceptive processing is important for appropriate motor control, providing error-feedback and internal representation of movement for adjusting the motor command. Although proprioceptive functioning improves during childhood and adolescence, we still have few clues about how the proprioceptive brain network develops. Here, we investigated developmental changes in the functional organization of this network in early adolescents (n = 18, 12 ± 1 years), late adolescents (n = 18, 15 ± 1), and young adults (n = 18, 32 ± 4), by examining task-evoked univariate activity and patterns of functional connectivity (FC) associated with seeds placed in cortical (supramarginal gyrus) and subcortical (dorsal rostral putamen) regions. We found that although the network is already well established in early adolescence both in terms of topology and functioning principles (e.g., long-distance communication and economy in wiring cost), it is still undergoing refinement during adolescence, including...
Différentes études sur la mise en place de stratégies sensorimotrices d'équilibre chez l'enfant s... more Différentes études sur la mise en place de stratégies sensorimotrices d'équilibre chez l'enfant sont rapportées dans cet article. Sur la base de ces résultats expérimentaux et de deux principes fonctionnels (le choix d'un référentiel stable et la maîtrise progressive des degrés de liberté des différentes articulations du corps), Assaiante et Amblard [7]ont récemment proposé un modèle ontogénétique simple et heuristique de la construction des stratégies d'équilibre depuis la naissance jusqu'à l'âge adulte. Ce modèle propose, au cours de quatre périodes successives de l'ontogenèse, l'existence d'un va-et-vient entre deux modes d'organisation temporelle du contrôle de l'équilibre: ascendant ou descendant, auxquels sont associés deux modes de fonctionnement des ensembles de segments corporels: en bloc ou articulé. De récentes études ont pour but de mettre à l'épreuve le degré de généralité des stratégies déjà identifiées et d'étendre la validation du modèle à des situations nouvelles qui impliquent un contrôle de l'équilibre lors des transitions entre les différentes phases du mouvement. Tout en introduisant un enrichissement des caractéristiques propres à chacune des périodes du modèle, les résultats obtenus lors des études développementales relatives au saut et à l'initiation de la marche sont tout à fait cohérents avec les principes fonctionnels qui sont à la base du modèle ontogénétique.A set of experimental studies showing how head-trunk coordination develops during childhood in various locomotor tasks is reported. On the basis of these results and two functional principles (stable reference frame and gradual mastery of the degrees of freedom of the body joints), an ontogenetic model for the sensorimotor organization of balance control in humans is proposed [7]. In this model, we adopt the hypothesis that the two main modes of equilibrium control (ascending vs descending temporal organization) operate alternatively and are associated with either of two modes of head-trunk linkage (“en bloc” vs articulated) during four successive periods in the course of ontogenesis. The advantage of this model is that is heuristic and therefore open to further improvements, including new subdivisions within the proposal periods, the generalization of these balance strategies to most of the posturo-kinetic activities, the comparison between unperturbed natural balance and reactions to transient postural disturbances. These latter proposal are illustrated by the study of new experimental tasks such as hops using one or two feet and initiation of gait. Although they introduce improvements, these new findings are consistent with the functional principles proposed in the previous ontogenetic model.
In the current study, we adopted the hypothesis that the body scheme disturbances occurring durin... more In the current study, we adopted the hypothesis that the body scheme disturbances occurring during adolescence might lead subjects to transiently neglect proprioceptive information and that adolescents might rely more strongly on vision to control their orientation and stabilize their body. To check this point, we asked adolescents 14-15 years to maintain vertical stance while very slow sinusoidal oscillations in the frontal plane were applied to the supporting platform at 0.01 Hz (below the detection threshold of the semicircular canal system) and at 0.06 Hz (above) with the eyes open and closed. Two postural components, orientation and segmental stabilization, were analyzed at the head, shoulder, trunk, and pelvis levels. At the lowest frequency without vision, the performances of adolescents were much less efficient than those of adults. Moreover, this study showed that vision plays a predominant role in adolescents' control of orientation and body stabilization. At 0.06 Hz without vision, a clearcut difference was observed between the strategies used by girls and boys; specifically, the maturation of the segmental stabilization processes was found to be more advanced in girls than in boys. However, no such difference was observed at 0.01 Hz. Lastly, comparisons between the data obtained in adolescents and those previously obtained in young adults (Vaugoyeau, Viel, Amblard, Azulay, & Assaiante, 2008) clearly show that adolescents use different postural strategies and that they are not yet capable of reaching comparable postural performance levels to those observed in adults. Because adolescents were not able to use the proprioceptive information available to improve their postural control, we concluded that they showed a maturational lag in comparison with adults. This suggests that the mechanisms underlying postural control are still maturing during adolescence, which might constitute a transient period of proprioceptive neglect in sensory integration of postural control.
ABSTRACT Agir avec son environnement nécessite d’être conscient de son propre corps. Cette consci... more ABSTRACT Agir avec son environnement nécessite d’être conscient de son propre corps. Cette conscience corporelle est basée sur le schéma corporel qui correspond à la représentation interne du corps en action. La construction du schéma corporel au cours de l’ontogénèse repose grandement sur la proprioception. La maturation des bases cérébrales sous-jacentes à l’intégration proprioceptive reste encore peu connue. C’est autour de 8 ans que l’intégration d’informations proprioceptives au service du contrôle en ligne du mouvement devient plus opérationnelle, signant une maturation progressive des afférences proprioceptives (Contreras-Vidal et al., 2006). De plus, une immaturité du réseau proprioceptif a été observée chez les adolescents, qui se caractérise par une moindre différentiation en comparaison des adultes (Cignetti et al., 2014 ; Assaiante et al., 2014).
Revue de laryngologie - otologie - rhinologie, 2009
The objective of the study was to assess how posture and vocal acoustics are modified when one ne... more The objective of the study was to assess how posture and vocal acoustics are modified when one needs to communicate despite environmental obstacles (i.e. vocal effort performance). 20 healthy young women participated to this study. They had to communicate numbers to a listener. Environmental obstacles were the distance between the subject and the auditor, and the noise. Segmental posture modifications were recorded and analyzed using the numerical infra-red system for movement analysis SMART. Vocal acoustics and electroglottography were also recorded and analyzed using the EVA system. The study showed the presence of objective postural modifications during vocal effort. Their amplitude increased when the environmental obstacles to communications increased, and they anticipated the vocal production. The vocal effort concept and its relation with the posture, the voice and the subject's feeling are reviewed on the basis of these results. Laryngeal effort is not isolated, but belon...
Journal of vestibular research : equilibrium & orientation
The main purpose of this study was to investigate the development of head-trunk coordination duri... more The main purpose of this study was to investigate the development of head-trunk coordination during single hops using one foot or two feet in children of two ages (5.5 to 6 and 7 to 7.5) and adults (n = 6/group). The kinematics of the subjects' hops were analyzed by means of an automatic optical TV-image processor called the ELITE system. The absolute angular dispersion of the head, trunk, and leg about the pitch and the roll axis were measured. Head and trunk pitch and roll anchoring indexes were calculated in order to compare the stabilization of a given segment with respect both to external space and to the underlying anatomical segment. Results were analyzed separately for 3 phases: take-off, flight, and landing. Only the last two phases, flight and landing, are presented in this paper, and the following was found: 1) During flight, under both unipedal and bipedal conditions, head and trunk stabilization in space about the pitch axis occurred in children as well as in adults...
The feeling of illusory movement is considered important in the study of human behavior because i... more The feeling of illusory movement is considered important in the study of human behavior because it is deeply related to motor consciousness. However, the neural basis underlying the illusion of movement remains to be understood. Following optimal vibratory stimulation of muscle tendon, certain subjects experience illusory movements while others do not. In the present fMRI study, we sought to uncover the neural basis of illusory movement awareness by contrasting a posteriori these two types of subjects. Examining fMRI data using leave-one-subject-out general linear models and region of interest analyses, we found that a non-limb-specific associative network, including the opercular part of the right inferior frontal gyrus and the right inferior parietal lobule, was more active in subjects with illusions. On the other hand, levels of activation in other brain areas involved in kinaesthetic processing were rather similar between the two subsamples of subjects. These results suggest that activation of the right inferior frontoparietal areas, once passed a certain threshold, forms the basis of illusory movements. This is consistent with the global neuronal workspace hypothesis that associates conscious processing with surges of frontoparietal activity.
The aim of this study was to explore, during adolescence, alterations in the use of a sensori-mot... more The aim of this study was to explore, during adolescence, alterations in the use of a sensori-motor representation as unveiled by the measurement of anticipatory postural control in a bimanual load-lifting task. We hypothesised that adolescence constitutes a period of refinement of anticipatory postural control due to on-going updates of the body schema and sensori-motor representations. The anticipatory postural control was assessed using a bimanual load-lifting paradigm in which subjects stabilise their left postural forearm, which is supporting an object, while they use their right hand to lift up the object. Kinematics and electromyographic data were recorded in two groups of adolescents (11-13 and 14-16 years of age) and a group of adults. Age and gender effects were tested. During voluntary unloading, the postural forearm stabilisation in adolescents was still different from the adult one, suggesting that further improvement of the postural forearm stabilisation must take place after the age of 16. No differences occur in the two adolescent groups. Moreover, girls presented a better stabilisation of the postural forearm than boys, indicating an earlier refinement of anticipatory postural control. The decrease of activity over postural flexors, which ensure postural stabilisation, appeared later in adolescents with respect to adults. Delayed timing adjustments and increased variability could reflect intense developmental processes underlain by an intense period of CNS maturation during adolescence. We discuss the role of brain maturation in the refinement of sensori-motor representations and the update of body schema.
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Papers by Christine Assaiante