Papers by Christophe Bourdin
Éditions de la Maison des sciences de l’homme eBooks, 2012
L’intelligence sensorimotrice Considérer la motricité humaine comme un objet d’étude scientifique... more L’intelligence sensorimotrice Considérer la motricité humaine comme un objet d’étude scientifique est une motivation relativement récente, puisqu’à peine plus d’un siècle s’est écoulé depuis les études de Woodworth (1899). Depuis ces travaux fondateurs, que de chemin parcouru ! Parmi les facteurs pouvant expliquer cet intérêt, le principal est sans doute notre curiosité à comprendre comment nous, êtres humains, bougeons. Bien que certains animaux puissent se déplacer plus vite, quelquefois de..
Neuropsychologia, Aug 1, 2019
Peripersonal space can be considered as the interface between the body and the environment, where... more Peripersonal space can be considered as the interface between the body and the environment, where objects can be reached and which may serve as a reference for the central nervous system with regard to possible actions. Peripersonal space can be studied by assessing the perception of the reachable space, which depends on the body's physical characteristics (i.e., arm length) since their modifications have been shown to be associated with a change in peripersonal space representation. However, it remains unclear whether the representation of limb dynamics also influences the representation of peripersonal space. The present study investigated this issue by perturbing the force-field environment. A novel force field was created by rotating an experimental platform where participants were seated while they reached towards visual targets. Manual reaching performance was assessed before, during and after platform rotation. Crucially, perception of peripersonal space was also assessed, with reachability judgments, before and after platform rotation. As expected, sensori-motor adaptation to the perturbed force field was observed. Our principal finding is that peripersonal space was systematically perceived as closer to the body after force-field adaptation. Two control experiments showed no significant difference in reachability judgments when no reaching movements were performed during platform rotation or when reaching movements were performed without platform rotation, suggesting that the change in perceived peripersonal space resulted from exposure to new limb dynamics. Overall, our findings show that sensori-motor adaptation of reaching movements to a new force field, which does not directly influence arm length but results in the updating of the arm's internal model of limb dynamics, interacts with the perceptual categorisation of space, supporting a motor contribution to the representation of peripersonal space.
HAL (Le Centre pour la Communication Scientifique Directe), 1999
Experimental Brain Research, Oct 23, 2020
Most of our daily interactions with objects occur in the space immediately surrounding the body, ... more Most of our daily interactions with objects occur in the space immediately surrounding the body, i.e. the peripersonal space. The peripersonal space is characterized by multisensory processing of objects which are coded in terms of potential actions, specifying for instance whether objects are within reach or not. Our recent work suggested a link between exposure to a new force field, which changed the effector dynamics, and the representation of peripersonal space. To better understand the interplay between the plasticity of the motor system and peripersonal space representation, the present study examined whether changing the direction of the force field specifically modified the perception of action boundaries. Participants seated at the centre of an experimental platform estimated visual targets' reachability before and after adapting upper-limb reaching movements to the Coriolis force generated by either clockwise or counterclockwise rotation of the platform (120°/s). Opposite spatial after-effects were observed, showing that force-field adaptation depends on the direction of the rotation. In contrast, perceived action boundaries shifted leftward following exposure to the new force field, regardless of the direction of the rotation. Overall, these findings support the idea that abrupt exposure to a new force field results in a direction-specific updating of the central sensorimotor representations underlying the control of arm movements. Abrupt exposure to a new force field also results in a nonspecific shift in the perception of action boundaries which is consistent with a contraction of the peripersonal space and could be related to its protective role. Such effect, which does not appear to be related to state anxiety, and could be related to theits protective role of the peripersonal space in response to the uncertainty of the sensorimotor system induced by the abrupt modification of the environment.
Scientific Reports, Dec 1, 2020
Transportation Research Part F: Traffic Psychology and Behaviour
In humans, body segments' position and movement can be estimated from multiple senses such as vis... more In humans, body segments' position and movement can be estimated from multiple senses such as vision and proprioception. It has been suggested that vision and proprioception can influence each other and that upper-limb proprioception is asymmetrical, with proprioception of the non-dominant arm being more accurate and/or precise than proprioception of the dominant arm. However, the mechanisms underlying the lateralization of proprioceptive perception are not yet understood. Here we tested the hypothesis that early visual experience influences the lateralization of arm proprioceptive perception by comparing 8 congenitallyblind and 8 matched, sighted right-handed adults. Their proprioceptive perception was assessed at the elbow and wrist joints of both arms using an ipsilateral passive matching task. Results support and extend the view that proprioceptive precision is better at the nondominant arm for blindfolded sighted individuals. While this finding was rather systematic across sighted individuals, proprioceptive precision of congenitally-blind individuals was not lateralized as systematically, suggesting that lack of visual experience during ontogenesis influences the lateralization of arm proprioception.
PLOS ONE
Introduction Identification of the seat features that could improve driving experience is a main ... more Introduction Identification of the seat features that could improve driving experience is a main issue for automotive companies. Objective Long duration real driving sessions were performed to assess the effect of three seats (soft–S1, firm–S2 and suspended–S3) on perceived discomfort and neuromuscular fatigue (NMF). Materials & methods For each seat, the muscular activity of bilateral Trapezius Descendens (TD), Erector Spinae (ES) and Multifidus (MF) muscles of twenty-one participants was recorded during real driving sessions of 3-hours each lasting approximately 3 hours and following the same itinerary. During each driving session, participants were also regularly asked to self-evaluate their level of whole-body and local discomfort. In addition, an endurance static test (EST) was performed before (ESTpre) and after (ESTpost) each driving session to assess the seat effect on physical capacity. Results Whole-body discomfort increased with driving time for all seats, but this increa...
Frontiers in Human Neuroscience, 2022
Car sickness is a major concern for car passengers, and with the development of autonomous vehicl... more Car sickness is a major concern for car passengers, and with the development of autonomous vehicles, increasing numbers of car occupants are likely to be affected. Previous laboratory studies have used EEG measurements to better understand the cerebral changes linked to symptoms. However, the dynamics of motion in labs/simulators differ from those of a real car. This study sought to identify specific cerebral changes associated with the level of car sickness experienced in real driving conditions. Nine healthy volunteers participated as front passengers in a slalom session inducing lateral movements at very low frequency (0.2 Hz). They were continuously monitored via EEG recordings and subjectively rated their level of symptoms after each slalom, using a 5-point likert scale. Car-sickness symptoms evolved concomitantly with changes in theta and alpha power in the occipital and parietal areas. These changes may reflect altered sensory integration, as well as a possible influence of s...
IEEE Access, 2020
The pedal force effectiveness, an important parameter in cycling performance, is rarely optimal. ... more The pedal force effectiveness, an important parameter in cycling performance, is rarely optimal. Decreased power is generally observed during the recovery phase (the cyclist does not pull enough). An essential part of training for cyclists consists in improving pedaling technique. Visual feedback can be useful but may not be feasible in real life, where the cyclist has to visually focus on the road. We propose auditive feedback as a better way to help cyclists improve their pedal force effectiveness in real-time. In this study, both competitive cyclists and non-cyclists tested different online sonification strategies of force effectiveness, comparing them to a silent control. The ''Squeak'' strategy, generating a squeak when torque was negative, had the most positive impact on Torque Effectiveness: some participants managed to eliminate any negative torque for a full minute. INDEX TERMS Cycling ergometer, movement execution efficiency, torque effectiveness.
Neuroscience, 2016
Astronauts' training is conventionally performed in a pool to reproduce weightlessness by exploit... more Astronauts' training is conventionally performed in a pool to reproduce weightlessness by exploiting buoyancy which is supposed to reduce the impact of gravity on the body. However, this training method has not been scientifically validated yet, and requires first to study the effects of underwater exposure on motor behavior. We examined the influence of neutral buoyancy on kinematic features of whole-body reaching underwater and compared them with those produced on land. Eight professional divers were asked to perform arm reaching movements toward visual targets while standing. Targets were presented either close or far from the subjects (requiring in the latter case an additional whole-body displacement). Reaching movements were performed on land or underwater in two different contexts of buoyancy. The divers either wore a diving suit only with neutral buoyancy applied to their center of mass or were additionally equipped with a submersible simulated space suit with neutral buoyancy applied to their body limbs. Results showed that underwater exposure impacted basic movement features, especially movement speed which was reduced. However, movement kinematics also differed according to the way buoyancy was exerted on the whole-body. When neutral buoyancy was applied to the center of mass only, some focal and postural components of whole-body reaching remained close to land observations, notably when considering the relative deceleration duration of arm elevation and concomitant forward trunk bending when reaching the far target. On the contrary, when neutral buoyancy was exerted on body segments, movement kinematics were close to those reported in weightlessness, as reflected by the arm deceleration phase and the whole-body forward displacement when reaching the far target. These results suggest that astronauts could benefit from the application of neutral buoyancy across the wholebody segments to optimize underwater training and acquire specific motor skills which will be used in space.
Perceptual and Motor Skills
Proprioception is the sense of position and movement of body segments. The widespread distributio... more Proprioception is the sense of position and movement of body segments. The widespread distribution of proprioceptors in human anatomy raises questions about proprioceptive uniformity across different body parts. For the upper limbs, previous research, using mostly active and/or contralateral matching tasks, has suggested better proprioception of the non-preferred arm, and at the elbow rather than the wrist. Here we assessed proprioceptive perception through an ipsilateral passive matching task by comparing the elbow and wrist joints of the preferred and non-preferred arms. We hypothesized that upper limb proprioception would be better at the elbow of the non-preferred arm. We found signed errors to be less variable at the non-preferred elbow than at the preferred elbow and both wrists. Signed errors at the elbow were also more stable than at the wrist. Across individuals, signed errors at the preferred and non-preferred elbows were correlated. Also, variable signed errors at the pre...
Journal of vestibular research, Oct 14, 2004
The way in which the head is controlled in roll was investigated by dissociating the body axis an... more The way in which the head is controlled in roll was investigated by dissociating the body axis and the gravito-inertial force orientation. Seated subjects (N = 8) were requested to align their head with their trunk, 30 degrees to the left, 30 degrees to the right or with the gravito-inertial vector, before, during (Per Rotation), after off-center rotation and on a tilted chair without rotation (Tilted). The gravito-inertial vector angle during rotation and the chair tilt angle were identical (17 degrees ). The subjects were either in total darkness or facing a visual frame that was fixed to the trunk. Both final error and within-subject variability of head positioning increased when the body axis and the gravito-inertial vector were dissociated (Per Rotation and Tilted). However, the behavior was different depending on whether the subjects were in the Tilted or Per Rotation conditions. The presentation of the visual frame reduced the within-subject variability and modified the perception of the gravito-inertial vector's orientation on the tilted chair. As head positioning with respect to the body and sensing of the gravito-inertial vector are modified when body axis and gravito-inertial vector orientation are dissociated, the observed decrease in performance while executing motor tasks in a gravito-inertial field may be at least in part attributed to the inaccurate sensing of head position.
Journal of vestibular research, Nov 1, 2006
A major issue in motor control studies is to determine whether and how we use spatial frames of r... more A major issue in motor control studies is to determine whether and how we use spatial frames of reference to organize our spatially oriented behaviors. In previous experiments we showed that simulated body tilt during off-axis rotation affected the performance in verbal localization and manual pointing tasks. It was hypothesized that the observed alterations were at least partly due to a change in the orientation of the egocentric frame of reference, which was indeed centered on the body but aligned with the gravitational vector. The present experiments were designed to test this hypothesis in a situation where no inertial constraints (except the usual gravitational one) exist and where the orientation of the body longitudinal z-axis was not aligned with the direction of the gravity. Eleven subjects were exposed to real static body tilt and were required to verbally localize (experiment 1) and to point as accurately as possible towards (experiment 2) memorized visual targets, in two conditions, Head-Free and Head-Fixed conditions. Results show that the performance was only affected by real body tilt in the localization task performed when the subject's head was tilted relative to the body. Thus, dissociation between gravity and body longitudinal z-axis alone is not responsible for localization nor for pointing errors. Therefore, the egocentric frame of reference seems independent from the orientation of the gravity with regard to body z-axis as expected from our previous studies. Moreover, the use of spatial referentials appears to be less mandatory than expected for pointing movements (motor task) than for localization task (cognitive task).
IEEE Transactions on Intelligent Transportation Systems, Dec 1, 2013
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Neuroreport, Aug 1, 2002
The present study tested whether vestibular input can be processed on-line to control goal-direct... more 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 accuracy with which subjects reached for the target when the rotation occurred before the movement. Subjects were less accurate in updating the internal representation of visual space through vestibular signals than in monitoring on-line body orientation to control arm movement. These results demonstrate that vestibular signals contribute to motor control of voluntary arm movements and suggest that the processes underlying on-line regulation of goal-directed movements are di¡erent from those underlying navigation-like behaviors.
Progress in Brain Research, 2003
This chapter is divided into three main parts. Firstly, on the basis of the literature, we will s... more This chapter is divided into three main parts. Firstly, on the basis of the literature, we will shortly discuss how the recent introduction of the concept of internal models by Daniel Wolpert and Mitsuo Kawato contributes to a better understanding of what is motor learning and what is motor adaptation. Then, we will present a model of eye-hand co-ordination during self-moved target tracking, which we used as a way to specifically address these topics. Finally, we will show some evidence about the use of proprioceptive information for updating the internal models, in the context of eye-hand co-ordination. Motor and afferent information appears to contribute to the parametric adjustment (adaptation) between arm motor command and visual information about arm motion. The study reported here was aimed at assessing the contribution of arm proprioception in building (learning) and updating (adaptation) these representations. The subjects (including a deafferented subject) had to make back and forth movements with their forearm in the horizontal plane, over learned amplitude and at constant frequency, and to track an arm-driven target with their eyes. The dynamical conditions of arm movement were altered (unexpectedly or systematically) during the movement by changing the mechanical properties of the manipulandum. The results showed a significant change of the latency and the gain of the smooth pursuit system, before and after the perturbation for the control subjects, but not for the deafferented subject. Moreover, in control subjects, vibrations of the arm muscles prevented adaptation to the mechanical perturbation. These results suggest that in a self-moved target tracking task, the arm motor system shares with the smooth pursuit system an internal representation of the arm dynamical properties, and that arm proprioception is necessary to build this internal model. As suggested by Ghez et al. (1990) (Cold Spring Harbor Symp. Quant. Biol., 55: 837-8471), proprioception would allow control subjects to learn the inertial properties of the limb.
HAL (Le Centre pour la Communication Scientifique Directe), 2015
Virtual reality (driving simulators) tends to generalize for the study of human behaviour in mobi... more Virtual reality (driving simulators) tends to generalize for the study of human behaviour in mobility. It is thus crucial to ensure that perception of space and motion is little or not affected by the virtual environment (VE). The aim of this study was to determine a metrics of distance perception in VEs and whether this metrics depends on interactive factors: stereoscopy and motion parallax. After a training session, participants were asked, while driving, to estimate the relative location (5 to 80 m) of a car on the same road. The overall results suggest that distance perception in this range does not depend on interactive factors. In average, as generally reported, subjects underestimated the distances whatever the vision conditions. However, the study revealed a large interpersonal variability: two profiles of participants were defined, those who quite accurately perceived distances in VR and those who underestimated distances as usually reported. Overall, this classification was correlated to the level of performance of participants during the training phase. Furthermore, learning performance is predictive of the behavior of participants.
HAL (Le Centre pour la Communication Scientifique Directe), 2011
Shape and mechanical structure of instruments play a large part in the lack of ergonomics during ... more Shape and mechanical structure of instruments play a large part in the lack of ergonomics during laparoscopic surgery. Providing intra-abdominal mobility and rethinking handles design are two solutions to increase comfort and precision of gestures. Based on previous work that determined the optimal intra-abdominal kinematics, this study analyses the influence of handle design on both gesture and ergonomic performance. A virtual reality laparoscopic simulator was developed to perform an experimental comparison between two novel robotized instruments and standard ones. A group of 10 surgeons and 6 researchers in robotics carried out two representative surgical tasks with each instrument. Based on instrument and arm segments tracking, a gesture performance index and an ergonomic performance index were computed. The study demonstrates that distal mobilities combined with improved handle design and integration increase ergonomic level during laparoscopy and facilitate complex gestures.
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Papers by Christophe Bourdin