Jean Blouin

Jean Blouin
French National Centre for Scientific Research, Marseille

PhD

About

135
Publications
13,252
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Publications

Publications (135)
Preprint
Being the first stimulated by the relative movement of foot skin and the underneath moving support surface, the plantar tactile receptors (i.e., mechanoreceptors) play an important role in the sensorimotor transformation giving rise to a postural reaction. In this light, a surface (i.e., biomimetic) complying with the characteristics of the mechano...
Preprint
A few years after their bilateral vestibular loss, individuals usually show a motor repertoire that is almost back to normal. This recovery is thought to involve an up-regulation of the visual and proprioceptive information that compensates for the lack of vestibular information. Here, we investigated whether plantar tactile inputs, which provide b...
Article
Full-text available
Most of our knowledge on the human neural bases of spatial updating comes from functional magnetic resonance imaging (fMRI) studies in which recumbent participants moved in virtual environments. As a result, little is known about the dynamic of spatial updating during real body motion. Here, we exploited the high temporal resolution of electroencep...
Preprint
Most of our knowledge on the human neural bases of spatial updating comes from fMRI studies in which recumbent participants moved in virtual environments. As a result, little is known about the dynamic of spatial updating during real body motion. Here, we exploited the high temporal resolution of electroencephalography (EEG) to investigate the dyna...
Article
Full-text available
Cutaneous foot receptors are important for balance control and their activation during quiet standing depends on the speed and the amplitude of postural oscillations. We hypothesized that the transmission of cutaneous input to the cortex is reduced during prolonged small postural sways, due to receptor adaptation during continued skin compression....
Article
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Studies on goal-directed arm movements have shown a close link between feedforward and feedback control in protocols where both planning and online control processes faced a similar type of perturbation, either mechanical or visual. This particular context might have facilitated the use of an adapted internal model by feedforward and feedback contr...
Article
Background The anticipatory postural adjustments (APA) associated with step initiation are impaired in obese patients (e.g. longer duration, greater lateral center of pressure excursion). This could arise from the known altered internal representation of the body in obese individuals as this representation is crucial for enhancing the processing of...
Article
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The way we can correct our ongoing movements to sudden and unforeseen perturbations is key to our ability to rapidly adjust our behavior to novel environmental demands. Referred to as sensorimotor flexibility, this ability can be assessed by the double-step paradigm in which participants must correct their ongoing arm movements to reach targets tha...
Article
Introduction Important for balance control, the activation of the cutaneous foot receptors largely depends on the speed and amplitude of the body oscillations during standing. Material and methods Here, we tested the hypothesis that the transmission of cutaneous inputs to the cortex is reduced during prolonged intervals of small body sways due to...
Article
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A challenge in motor control research is to understand the mechanisms underlying the transformation of sensory information into arm motor commands. Here, we investigated these transformation mechanisms for movements whose targets were defined by information issued from body rotations in the dark (i.e., idiothetic information). Immediately after bei...
Article
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Prior to goal-directed actions, somatosensory target positions can be localized using either an exteroceptive or an interoceptive body representation. The goal of the present study was to investigate if the body representation selected to plan reaches to somatosensory targets is influenced by the sensory modality of the cue indicating the target’s...
Article
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When performing upper limb reaches, the sensorimotor system can adjust to changes in target location even if the reaching limb is not visible. To accomplish this task, sensory information about the new target location and the current position of the unseen limb are used to program online corrections. Previous researchers have argued that, prior to...
Article
Full-text available
When performing upper limb reaches, the sensorimotor system can adjust to changes in target location even if the reaching limb is not visible. To accomplish this task, sensory information about the new target location and the current position of the unseen limb are used to program online corrections. Previous researchers have argued that, prior to...
Article
Somatosensory inputs to the cortex undergo an early and a later stage of processing which are characterized by an early and a late somatosensory evoked potentials (SEP). The early response is highly representative of the stimulus characteristics whereas the late response reflects a more integrative, task specific, stage of sensory processing. We hy...
Data
Estimated source maps on the cortical surface (LORETA) based on the grand average of the 7 left-handers with a left DE following a (A) right visual field (RVF) or (B) left visual field (LVF) stimulation. For each part, the left panel corresponds to the source localization at the latency of N160 peak recorded over the hemisphere contralateral to the...
Data
Estimated source maps on the cortical surface (LORETA) based on the grand average of the 11 right-handers with a left DE after (A) right visual field (RVF) and (B) left visual field (LVF) stimulations. For each part, the left panel corresponds to the source localization at the latency of N160 peak recorded over the hemisphere contralateral to the s...
Data
Estimated source maps on the cortical surface (LORETA) based on the grand average of the 7 left-handers with a right DE after (A) right visual field (RVF) or (B) left visual field (LVF) stimulations. For each part, the left panel corresponds to the source localization at the latency of N160 peak recorded over the hemisphere contralateral to the sti...
Article
Full-text available
The interhemispheric transfer of information is a fundamental process in the human brain. When a visual stimulus appears eccentrically in one visual-hemifield, it will first activate the contralateral hemisphere but also the ipsilateral one with a slight delay due to the interhemispheric transfer. This interhemispheric transfer of visual informatio...
Research
Full-text available
A classical visuo-manual adaptation protocol carried out on a rotating platform was used to test the ability of subjects to adapt to centrifugal and Coriolis forces when visual feedback of the arm is manipulated. Three main results emerge: (a) an early modi®cation of the initial trajectory of the movements takes place even without visual feedback o...
Research
Full-text available
The present study tested whether vestibular input can be processed on-line to control goal-directed arm movements towards memorized visual targets when the whole body is passively rotated during movement execution. Subjects succeeded in compensating for current body rotation by regulating ongoing arm movements.This performance was compared to the a...
Research
Full-text available
Using galvanic vestibular stimulation (GVS), we tested whether a change in vestibular input at the onset of goal-directed arm movements induces deviations in arm trajectory. Eight head-fixed standing subjects were instructed to reach for memorized visual targets in complete darkness. In half of the trials, randomly-selected, a 3 mA bipolar binaural...
Article
Previous studies have revealed that visual and somatosensory information is processed as a function of its relevance during movement execution. We thus performed spectral decompositions of ongoing neural activities within the somatosensory and visual areas while human participants performed a complex visuomotor task. In this task, participants foll...
Article
Unlike handedness, sighting eye dominance, defined as the eye unconsciously chosen when performing monocular tasks, is very rarely considered in studies investigating cerebral asymmetries. We previously showed that sighting eye dominance has an influence on visually triggered manual action with shorter reaction time (RT) when the stimulus appears i...
Article
Full-text available
Adolescent idiopathic scoliosis is a multifactorial disorder including neurological factors. A dysfunction of the sensorimotor networks processing vestibular information could be related to spine deformation. This study investigates whether feed-forward vestibulomotor control or sensory reweighting mechanisms are impaired in adolescent scoliosis pa...
Article
The contribution of vestibular signals to motor control has been evidenced in postural, locomotor, and oculomotor studies. Here, we review studies showing that vestibular information also contributes to the control of arm movements during whole-body motion. The data reviewed suggest that vestibular information is used by the arm motor system to mai...
Poster
Full-text available
Our dominant eye is the one we unconsciously choose when performing a monocular task. Several studies revealed that the stimulation of this dominant eye activates a larger cerebral network than the stimulation of the non-dominant eye. Nevertheless, the consequences of this lateralization of the visual system in sensorimotor tasks has been poorly ex...
Article
Full-text available
It has been shown that during the planning of a voluntary movement, the transmission of cutaneous afferent inputs to the somatosensory cortex is attenuated shortly before the motor output, as well as during movement execution. However, it is not known if the sensory suppression observed during the planning phase (i.e., before any execution) is a sy...
Article
Notre œil dominant est celui que nous choisissons inconsciemment lorsque nous avons à réaliser des tâches monoculaires. Dans le domaine de la clinique neuro-ophtalmologique, il est démontré que la dominance oculaire (DO) joue un rôle de premier plan dans bon nombre de pathologies de l’œil. Par ailleurs, la quantification précise de cette DO s’avère...
Article
Full-text available
Introduction.- The dominant eye is defined as the one we unconsciously choose when we have to perform monocular tasks. In the field of clinical neuro-ophthalmology it is well-established that eye dominance plays a key role in several eye diseases. Furthermore, the accurate quantification of eye dominance might be relevant within the framework of so...
Article
Full-text available
We recently found that the cortical response to proprioceptive stimulation was greater when participants were planning a step than when they stood still, and that this sensory facilitation was suppressed in microgravity. The aim of the present study was to test whether the absence of gravity-related sensory afferents during movement planning in mic...
Article
Full-text available
Behavioral studies have suggested that the brain uses a visual estimate of the hand to plan reaching movements towards visual targets and somatosensory inputs in the case of somatosensory targets. However, neural correlates for distinct coding of the hand according to the sensory modality of the target have not yet been identified. Here we tested t...
Article
Full-text available
When tracing a template with mirror-reversed vision (or distorted vision), the sensory information arising from the movement does not match the expected sensory consequences. In such situations, participants have to learn a new visuomotor mapping in order to trace the template with an accuracy and speed approaching that observed when tracing with d...
Article
Full-text available
Several studies have investigated whether vestibular signals can be processed to determine the magnitude of passive body motions. Many of them required subjects to report their perceived displacements offline, i.e., after being submitted to passive displacements. Here, we used a protocol that allowed us to complement these results by asking subject...
Article
Full-text available
Background Rotation of the torso while reaching produces torques (e.g., Coriolis torque) that deviate the arm from its planned trajectory. To ensure an accurate reaching movement, the brain may take these perturbing torques into account during movement planning or, alternatively, it may correct hand trajectory during movement execution. Irrespectiv...
Article
Full-text available
Several studies showed that the transmission of afferent inputs from the periphery to the somatosensory cortex is attenuated during the preparation of voluntary movements. Here, we tested whether sensory attenuation is also observed during the preparation of a voluntary step. It would appear dysfunctional to suppress somatosensory information which...
Article
Full-text available
Gait initiation is preceded by initial postural adjustments whose goal is to set up the condition required for the execution of the focal stepping movement. For instance, the step is preceded by a shift of the body's center of mass towards the stance foot unloading the stepping leg. This displacement is produced by exerting forces on the ground (i....
Article
Full-text available
Gravitational force level is well-known to influence arm motor control. Specifically, hyper- or microgravity environments drastically change pointing accuracy and kinematics, particularly during initial exposure. These modifications are thought to partly reflect impairment in arm position sense. Here we investigated whether applying normogravitatio...
Article
Anticipatory postural adjustments (APAs) prior to step execution are thought to be immutable once released. Here we challenge this assumption by testing whether APAs can be modified online if a body perturbation occurs during execution. Two directions of perturbation (resisting and assisting) relative to the body weight transfer were used during th...
Article
Reaching for a target while rotating the trunk generates substantial Coriolis and centrifugal torques that push the arm in the opposite direction of the rotations. These torques rarely perturb movement accuracy, suggesting that they are compensated for during the movement. Here we tested whether signals generated during body motion (e.g., vestibula...
Article
In the absence of visual supervision, tilting the head sideways gives rise to deviations in spatially defined arm movements. The purpose of this study was to determine whether these deviations are restricted to situations with impoverished visual information. Two experiments were conducted in which participants were positioned supine and reproduced...
Article
Full-text available
The ability to control locomotion through the environment and to intercept, or avoid objects is fundamental to the survival of all locomotor species. The extent to which this control relies upon optic flow, visual direction cues or non-visual sensory inputs has long been debated. Here we look at the use of sensory information in young and middle-ag...
Article
Full-text available
Most reaching arm movements have amplitude and direction constraints. Here we investigated the interdependence of these movement parameters in terms of visual control. To do so, we asked human adults to look and reach toward targets such that, in a first experiment, both movement amplitude and direction had to be controlled. Randomly, hand visual f...
Article
Full-text available
A synergistic inclination of the whole body towards the supporting leg is required when producing a stepping movement. It serves to shift the centre of mass towards the stance foot. While the importance of sensory information in the setting of this postural adjustment is undisputed, it is currently unknown the extent to which proprioceptive afferen...
Article
Recent studies have revealed that vestibulomotor transformations contribute to maintain the hand stationary in space during trunk rotation. Here we tested whether these vestibulomotor transformations have the same latencies and whether they are subject to similar cognitive control than the visuomotor transformations during manual tracking of a visu...
Article
Full-text available
Adolescent idiopathic scoliosis is characterized by a three-dimensional deviation of the vertebral column and its etiopathogenesis is unknown. Various factors cause idiopathic scoliosis, and among these a prominent role has been attributed to the vestibular system. While the deficits in sensorimotor transformations have been documented in idiopathi...
Article
The parieto-frontal network plays a crucial role in the transformations that convert visual information into motor commands for hand reaching movements. Here we use electroencephalography to determine whether the planning of reaching movements to visual and somatosensory targets involves a similar spatio-temporal pattern of neural activity. Subject...
Article
Full-text available
Upon exposure to novel visuomotor relationships, the information carried by visual and proprioceptive signals becomes discrepant, often disrupting motor execution. It has been shown that degradation of the proprioceptive sense (arising either from disease or experimental manipulation) enhances performance when drawing with mirror-reversed vision. G...
Article
Stepping over an obstacle is preceded by a center of pressure (CoP) shift, termed anticipatory postural adjustments (APAs). It provides an acceleration of the center of mass forward and laterally prior to step initiation. The APAs are characterized in the lateral direction by a force exerted by the moving leg onto the ground, followed by an unloadi...
Article
Full-text available
Recent evidence suggests that planning a reaching movement entails similar stages and common networks irrespective of whether the target location is defined through visual or proprioceptive cues. Here we test whether the transformations that convert the sensory information regarding target location into the required motor output are common for both...
Data
Movie 2. Dynamic representations of the deafferented subject's CoP displacements for representative single trials of the GVS conditions.
Data
Full-text available
Table 1. T-tests comparing the length of the CoP displacements of the deafferented subject in all experimental conditions.
Data
Movie 1. Dynamic representations of the deafferented subject's CoP displacements for representative single trials of the Head centered and Head rotated eyes closed conditions.
Data
Full-text available
Table 2. T-tests comparing the maximal CoP lateral shifts produced by the deafferented subject in the GVS conditions.