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International audience; Embodied views of cognition propose that concepts are grounded in sensorimotor experience. Diverse aspects of sensorimotor experience, like action and context information, could play a key role in the formation and processing of manipulable object concepts. Specifically, contextual information could help to link specific actions experienced with different object exemplars. In this study, the effects of action and context priming on superordinate and basic-level categorization of manipulable objects were directly contrasted in 7- and 9-year-olds and in adults. Across the ages, results revealed a differential effect of hand and scene primes on conceptual processing at the superordinate and basic levels; the disadvantage of superordinate over basic-level categorization was reduced in the context priming condition in comparison to the action priming condition. The nature and role of contextual knowledge are discussed from a cognitive and a neurophysiological point of view. Directions for further developmental research on concepts are also considered.

International audience; The present study aimed to show that bidirectional reading and language exposure influence the position of egocentric reference (ER), the perceived direction of the body's sagittal axis proposed to act as an anchor for movements in extracorporeal space. Directional factors (e.g., visual scanning bias and reading habits) have been proposed to influence visuospatial performance, such as in line bisection and figure drawing. In past studies, bidirectional readers have been less consistent in demonstrating a bias compared to unidirectional readers. Using a straight-ahead pointing task to assess egocentric reference, we compared 14 unidirectional left-to-right readers (Uni-LR) to three bidirectional reading groups that differed in the reading direction of their native language and/or the level of their second language literacy: 16 low-English literate, native right-to-left, bidirectional readers (Lo-Bi-RL), 13 high-English literate, native right-to-left, bidirectional readers (Hi-Bi-RL), and 15 native left-to-right, bidirectional readers (Bi-LR). Participants were asked to point straight-ahead while blindfolded using either a left-to-right or a right-to-left scanning direction to approach the subjective sagittal midline. Uni-LRs showed left-side spatial bias when scanning left-to-right and right-side bias during right-to-left scanning, Bi-LRs and Lo-Bi-RLs (i.e., intermediate level or less in their second language) demonstrated the opposite pattern, and Hi-Bi-RLs showed left-side spatial bias regardless of scanning direction. Results are discussed in terms of accuracy and spatial bias regarding the interaction between reading direction and spatial cognition based on the level of bidirectional literacy and language exposure.

International audience; Since the observation of Auguste D. by Alöis Alzheimer, it is an acknowledged fact that writing is one of the cognitive functions that are weakened early in Alzheimer's disease (AD). This study aimed to examine the cognitive nature of this disorder and question the hypothesis of a standard progression (Platel et al., 1993) from lexical to other central and more peripheral processes. A large group of mild to moderate AD patients (n=59) and a group of healthy elderly controls were submitted to an extensive assessment of both the central and peripheral components of writing. A comparison of groups indicated that AD patients performed more poorly than controls on a wide range of writing measures. It revealed a predominantly lexical disorder, but also found evidence of associated disorders located at different stages in the spelling system (phonological route, graphemic buffer, allographic store, graphic motor patterns). A multiple single-case analysis, using a specific methodology, allowed us to delimit individual profiles of agraphia. It revealed a wide variety of agraphia syndromes, including a far from negligible number of patients with selective damage to one of the central or peripheral components, as well as patients with multiple writing impairments. A positive correlation was observed between the severity of the dementia and spelling/writing measures (lexical and allographic). This study does not support the hypothesis of a uniform progression. Rather, it points to heterogeneous profiles of agraphia and suggests that the first signs of writing impairment in AD stem from changes at different points in the broad anatomical network subserving spelling and writing abilities.

International audience; Three experiments were conducted to determine if the intention to perform motor sequences in the future results in similar patterns of activation and inhibition as observed for verbal scripts. In Experiments 1 and 2, intention was induced by informing one group that they would be tested on the tasks following acquisition; the other group was not informed of the retention test. Recognition tests administered prior to and after the retention test indicated a strong intention superiority effect. However, intention instructions provided either at the end of acquisition (Experiment 1) or before acquisition (Experiment 2) failed to impact acquisition or retention performance of the motor sequences, but did influence the latency of responding on the retention test. Experiment 3 was designed to replicate the results of Experiments 1 and 2 using a within-subjects design and extend these findings to observation. The results indicated that intention instructions resulted in a strong intention superiority effect for both the physical and observational practice participants, but the performance on the intentional tasks was enhanced only for the observational practice group.

International audience; Many everyday skills are unconsciously learned through repetitions of the same behaviour by binding independent motor acts into unified sets of actions. However, our ability to be consciously aware of producing newly and highly trained motor skills raises the question of the role played by conscious awareness of action upon skill acquisition. In this study we strengthened conscious awareness of self-produced sequential finger movements by way of asking participants to judge their performance in terms of maximal fluency after each trial. Control conditions in which participants did not make any judgment or performance-unrelated judgments were also included. Findings indicate that conscious awareness of action, enhanced via subjective appraisal of motor efficiency, potentiates sensorimotor learning and skilful motor production in optimising the processing and sequencing of action units, as compared to the control groups. The current work lends support to the claim that the learning and skilful expression of sensorimotor behaviours might be grounded upon our ability to be consciously aware of our own motor capability and efficiency.

The goal of this paper was (1) to investigate if gymnasts have a more stable standing posture than experts in other sports, and (2) to determine how much gymnasts are affected by the removal of vision in different postural tasks. Six expert gymnasts and six experts in other non-gymnastic sports were asked to maintain balance in three standing postures of increasing difficulty: bipedal, unipedal, and unipedal + unstable support (i.e. 7 cm thick foam surface). Each posture was tested successively with and without vision. Based on the displacement of the center of pressure (range and mean average speed), the results showed that when visual cues were available, postural sway increased with the difficulty of the task, but both groups had comparable performance in all the tasks. When vision was removed, although both groups demonstrated larger postural sway in the unipedal tasks, this effect was less accentuated for the gymnasts. We concluded that gymnasts are able to use the remaining sensory modalities to compensate for the lack of vision in unstable postures.

International audience; In this study we sought to determine whether testing promotes the generalization of motor skills during the process of encoding and/or consolidation. We used a dynamic arm movement task that required participants to reproduce a spatial-temporal pattern of elbow extensions and flexions with their dominant right arm. Generalization of motor learning was tested by the ability to transfer the original pattern (extrinsic transformation) or the mirrored pattern (intrinsic transformation) to the unpractised left arm. To investigate the testing effects during both encoding and consolidation processing, participants were administered an initial testing session during early practice before being evaluated on a post-practice testing session administered either 10min (Testing-Encoding group) or 24hr apart (Testing-Consolidation group), respectively. Control groups were required to perform a post-practice testing session administered after either a 10-min (Control-Encoding group) or 24-hr delay (Control-Consolidation group). The findings revealed that testing produced rapid, within-practice skill improvements, yielding better effector transfer at the 10-min testing for the Testing-Encoding group on both extrinsic and intrinsic transformation tests when compared with the Control-Encoding group. Furthermore, we found better performance for the Testing-Consolidation group at the 24-hr testing for extrinsic and intrinsic transformations of the movement pattern when compared with the Control-Consolidation group. However, our results did not indicate any significant testing advantage on the latent, between-session development of the motor skill representation (i.e., from the 10-min to the 24-hr testing). The testing benefits expressed at the 10-min testing were stabilised but did not extend during the period of consolidation. This indicates that testing contributes to the generalisation of motor skills during encoding but not consolidation.

International audience; The reserve hypothesis accounts for the lack of direct relationship between brain pathology and its clinical manifestations. Research has mostly focused on cognition; our objective is to examine whether the reserve hypothesis applies to motor function. We investigated whether education, a marker of reserve, modifies the association between white matter lesions (WMLs), a marker of vascular brain damage, and maximum walking speed (WS), an objective measure of motor function. We also examined the cross-sectional and longitudinal association between education and WS. Data are from 4,010 participants aged 65-85 years in the longitudinal Three-City-Dijon Study with up to 4 WS measures over 10 years. We examined the interaction between education and WMLs for baseline WS. We studied the association between education and repeated WS measures using linear mixed models, and the role of covariates in explaining the education-WS association. Education was strongly associated with baseline WS; the difference in mean WS between the high and low education groups (0.145 m/s, 95% confidence interval = 0.125-0.165) was equivalent to 7.4 years of age. WMLs were associated with slow WS only in the low education group (p interaction = 0.026). WS declined significantly over time (-0.194 m/s/10 years, 95% confidence interval = -0.206, -0.182), but education did not influence rate of decline. Anthropometric characteristics, parental education, general health, and cognition had the strongest role in explaining the baseline education-WS association. Participants with more education were less susceptible to WMLs' effect on motor function. Higher education was associated with better motor performances but not with motor decline. These results are consistent with the passive reserve hypothesis.

International audience; X-linked Duchenne muscular dystrophy (DMD) is frequently associated with a nonprogressive, cognitive defect attributed to the absence of dystrophin in the brain of DMD patients. The mutant mdx mouse, lacking in 427-kDa dystrophin in both muscle and brain tissues, is considered to be a valuable model of human DMD. In the present study, we compared mdx and C57BL/10 control mice and showed that mdx mice had impaired retention in a T-maze, delayed spontaneous alternation task 24 h, but not 6 h, after acquisition. mdx mice were not impaired in acquisition of a bar-pressing task on 4 consecutive days but showed poor retention 22 days after the last training session. Mutants and controls showed similar behavioral responses in free exploration and light/dark choice situations and did not differ in spontaneous locomotor activity or motor coordination. Retention impairments at long delays in mdx mice suggest a role of dystrophin in long-term consolidation processes.

International audience; OBJECTIVES: To study the responsiveness (sensitivity to change) of the Motor Function Measure (MFM) in detecting change in neuromuscular disease patients with the intent of using this measure in future clinical trials. DESIGN: Prospective cohort observational study. SETTING: Inpatient and outpatient facilities for follow-up and treatment of neuromuscular diseases. PARTICIPANTS: Patients (N=152) with various neuromuscular diseases aged 6 to 60 years. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE(S): We used the MFM total score and its 3 subscores on 2 measurements grossly 1 year apart. The physicians and the patients (or proxy) were asked to provide their perceived change in functional status since the first MFM. These changes were expressed in 3 outcomes: deterioration, stability, or improvement. RESULTS: The overall 12-month-standardized mean change of the total score mean ± SD annual total score change was -2.4±5.5 points (P

International audience; An experiment was conducted to determine if gating information to different hemispheres during observational training facilitates the development of a movement representation. Participants were randomly assigned to one of three observation groups that differed in terms of the type of visual half-field presentation during observation (right visual half-field (RVF), left visual half-field (LVF), or in central position (CE)), and a control group (CG). On Day 1, visual stimuli indicating the pattern of movement to be produced were projected on the respective hemisphere. The task participants observed was a 1300 ms spatial-temporal pattern of elbow flexions and extensions. On Day 2, participants physically performed the task in an inter-manual transfer paradigm with a retention test, and two contralateral transfer tests; a mirror transfer test which required the same pattern of muscle activation and limb joint angles and a non-mirror transfer test which reinstated the visual-spatial pattern of the sequence. The results demonstrated that participants of the CE, RVF and the LVF groups showed superior retention and transfer performance compared to participants of the CG. Participants of the CE- and LVF-groups demonstrated an advantage when the visual-spatial coordinates were reinstated compared to the motor coordinates, while participants of the RVF-group did not promote specific transfer patterns. These results will be discussed in the context of hemisphere specialization.

International audience; We investigated the practice-effects on motor skill transfer and the associated representational memory changes that occur during the within-practice and between-practice phases. In two experiments, participants produced extension-flexion movements with their dominant right arm for a limited or prolonged practice session arranged in either a single- or multi-session format. We tested the ability of participants to transfer the original pattern (extrinsic transformation) or the mirrored one (intrinsic transformation) to the non-dominant left arm, 10 min and 24 h after the practice sessions. Results showed that practice induces rapid motor skill improvements that are non-transferable irrespective of the amount of acquisition trials. Furthermore, the extrinsic component of the skill develops early and remains the dominant coding system during practice. Conversely, we found distinct between-practice memory changes: a limited practice induces an off-line development of the extrinsic component, whereas a prolonged practice session subserves the off-line development of the intrinsic component (experiment 2). We provided further evidence that the long-term representation of the motor skill also depends on the nature of the practice session itself: the parsing of practice into multiple sessions narrows the effector-transfer capacities in comparison to a single session (experiment 1). These findings yield theoretical and practical implications that are discussed in the context of recent motor skill learning models.

International audience; The intention to complete an action in the future can improve the learning of this action, but it is unknown whether this effect persists when feedback is manipulated during encoding. In experiment 1, participants were instructed to learn a motor skill with or without intending to reproduce this learning in the future, and feedback on their movements was administrated by self-decision, that is, participants asked for feedback whenever they wanted it. The results showed that intention increased the frequency with which feedback was requested, but did not improve motor performance. In experiment 2, participants had to learn the task with high or few feedbacks, which they could not control. In these conditions, intention was beneficial in promoting motor learning only for a low feedback schedule. We suggest that the beneficial effect of intention on learning can be overshadowed or emphasised by the feedback processing during encoding. These findings are discussed in light of theories surrounding prospective memory.

International audience; The brain easily generates the movement that is needed in a given situation. Yet surprisingly, the results of experimental studies suggest that it is difficult to acquire more than one skill at a time. To do so, it has generally been necessary to link the required movement to arbitrary cues. In the present study, we show that speech motor learning provides an informative model for the acquisition of multiple sensorimotor skills. During training, subjects were required to repeat aloud individual words in random order while auditory feedback was altered in real-time in different ways for the different words. We found that subjects can quite readily and simultaneously modify their speech movements to correct for these different auditory transformations. This multiple learning occurs effortlessly without explicit cues and without any apparent awareness of the perturbation. The ability to simultaneously learn several different auditory-motor transformations is consistent with the idea that, in speech motor learning, the brain acquires instance-specific memories. The results support the hypothesis that speech motor learning is fundamentally local.

International audience; This experiment was designed to assess the combined influence of practice schedule (blocked or random), task similarity (similar or dissimilar), and amount of practice on motor learning. Participants were required to perform three movement times (200, 350, 500 ms) in a blocked or random schedule while pointing towards the target located in the front direction in the similar condition, or towards three targets (left, front, and right) in the dissimilar condition. In each condition, participants completed 99 or 297 acquisition trials before a delayed retention test similar for all participants. Results indicated a contextual interference (CI) effect due to the schedule of practice following 297 trials for similar task: blocked schedule tended to produce better performance early in practice; random schedule enhanced learning for a larger amount of practice. However, when participants experienced dissimilar task variations, no blocked-random difference was found whatever the amount of practice. This suggests that task similarity is a learning variable that modulates the CI effect. Our findings argue for the evidence that the intertask processing evoked by random schedule is not sufficient to improve learning and that there may be a ceiling effect on retention performance due to the extent of additional intertask processing.

International audience; The reported study examined the cognitive processes underlying contextual interference (CI) in motor learning. This experiment was designed to assess the combined influence of practice schedule (blocked or random) and task similarity (similar or dissimilar) on acquisition and retention performance. Participants (N=60) learned a set of three variations of a timing task according to a similar (900, 1000 and 1100ms) or dissimilar parameter condition (700, 1000 and 1300ms) with either a blocked or random practice order: this resulted in 4 experimental groups. Performance in delayed retention demonstrated a typical CI effect due to the schedule of practice for the dissimilar parameter condition with the random practice group outperforming the blocked practice group. Conversely, no blocked-random difference was found for the similar parameter condition. These findings lend support for the reconstruction hypothesis by showing that supplementing random practice with additional intertask elaboration (i.e., similar parameter condition) did not facilitate subsequent retention performance.

International audience; Huntington disease (HD) is caused by an expansion of CAG repeat in the Huntingtin gene. Patients demonstrate a triad of motor, cognitive and psychiatric symptoms. A transgenic rat model (tgHD rats) carrying 51 CAG repeats demonstrate progressive striatal degeneration and polyglutamine aggregates in limbic structures. In this model, emotional function has only been investigated through anxiety studies. Our aim was to extend knowledge on emotional and motivational function in symptomatic tgHD rats. We subjected tgHD and wild-type rats to behavioral protocols testing motor, emotional, and motivational abilities. From 11 to 15 months of age, animals were tested in emotional perception of sucrose using taste reactivity, acquisition, extinction, and re-acquisition of discriminative Pavlovian fear conditioning as well as reactivity to changes in reinforcement values in a runway Pavlovian approach task. Motor tests detected the symptomatic status of tgHD animals from 11 months of age. In comparison to wild types, transgenic animals exhibited emotional blunting of hedonic perception for intermediate sucrose concentration. Moreover, we found emotional alterations with better learning and re-acquisition of discriminative fear conditioning due to a higher level of conditioned fear to aversive stimuli, and hyper-reactivity to a negative hedonic shift in reinforcement value interpreted in term of greater frustration. Neuropathological assessment in the same animals showed a selective shrinkage of the central nucleus of the amygdala. Our results showing emotional blunting and hypersensitivity to negative emotional situations in symptomatic tgHD animals extend the face validity of this model regarding neuropsychiatric symptoms as seen in manifest HD patients, and suggest that some of these symptoms may be related to amygdala dysfunction.

International audience; In 2 experiments, the authors assessed different knowledge of results (KR) schedules for observational and physical practice. In Experiment 1, participants had to learn a sequence timing task under either a bandwidth (KR being delivered when participants' performance was outside a predefined bandwidth or range) or yoked (same number of KRs provided as the bandwidth group) KR procedure. The results show that for both practice conditions the bandwidth KR schedule was more effective in promoting learning than the yoked schedule. During Experiment 2, a KR frequency was controlled (100% or 33% KR) and the data indicate that a reduced KR frequency only enhanced the learning of observers. Because a low KR frequency improves the sensory process controlling motor learning, the authors propose that action observation may be perceptual in nature.

International audience; Previous behavioral data suggest that the salience of taxonomic (e.g., hammer-saw) and thematic (e.g., hammer-nail) conceptual relations depends on object categories. Furthermore, taxonomic and thematic relations would be differentially grounded in the sensory-motor system. Using a picture matching task, we asked adult participants to identify taxonomic and thematic relations for non-manipulable and manipulable natural and artifact targets (e.g., animals, fruit, tools and vehicles, respectively) inside and outside a 3 T MR scanner. Behavioral data indicated that taxonomic relations are identified faster in natural objects while thematic relations are processed faster in artifacts, particularly manipulable ones (e.g., tools). Neuroimaging findings revealed that taxonomic processing specifically activates the bilateral visual areas (cuneus, BA 18), particularly for non-manipulable natural objects (e.g., animals). On the contrary, thematic processing specifically recruited a bilateral temporo-parietal network including the inferior parietal lobules (IPL, BA 40) and middle temporal gyri (MTG, BA 39/21/22). Left IPL and MTG activation was stronger for manipulable than for non-manipulable artifacts (e.g., tools vs. vehicles) during thematic processing. Right IPL and MTG activation was greater for both artifacts compared to natural objects during thematic processing (manipulable and non-manipulable ones, e.g., tools and vehicles). While taxonomic relations would selectively rely on perceptual similarity processing, thematic relations would specifically activate visuo-motor regions involved in action and space processing. In line with embodied views of concepts, our findings show that taxonomic and thematic conceptual relations are based on different sensory-motor processes. It suggests that they may have different roles in concept formation and processing depending on object categories.

This study examined age-related differences in the coordinative mechanism of the reach-to-grasp movement in three groups of children aged 6, 8, and 11 year, and in healthy adults. Three prehension conditions were manipulated: an unimanual and a bimanual self-driven tasks in which the reaching and grasping of the object were performed by participants, and a bimanual externally-driven task, in which the experimenter brought the object into the vicinity of the participant which grasped it. Classical kinematics data-peak velocities of the reaching and the grasping, the time to onset grip opening, maximum grip opening and grip closure-were calculated. Moreover, to obtain equivalent kinematics variables for all age groups, relative time to peak velocity (% of reaching duration), relative maximum grip opening (% of object size), and percentage of the four types of phase plans between reaching velocity and grip size have been calculated for each group of age. Our main results showed (1) a high variability at age 6, (2) an age-related change between the 6- and 8-year old for almost all of the dependent variables, and (3) a significant difference between the 11-year olds and adults. In summary, at 6 years, the interdependence between the reaching and grasping programs was unstable. A transitory feedback-based coordination between reaching and grasping appeared at 8 years of age. Finally, the adults' relationship between reaching and grasping was not attained at the age of 11.

International audience; Excitotoxic lesion of the striatum provides a useful model for evaluating the excitotoxic processes involved in neurological disorders, in particular stroke diseases. The behavioural outcome after such injury is however poorly described. We have therefore investigated the potential behavioural deficits induced by a NMDA-induced excitotoxic unilateral lesion of the lateral part of the striatum, by comparison with a PBS striatal injection (sham procedure), and non-operated mice behaviour. Three groups of male adult Swiss mice were constituted: unilateral NMDA (20 nmol striatal NMDA injection), sham (striatal PBS injection), and control (healthy non-operated mice). From 14 to 29 days post-surgery, sensorimotor and mnesic tests were performed in all groups. After euthanasia, immunohistochemical stainings (NeuN and GFAP) were performed in order to assess the size of the lesion. Straight runway and passive avoidance performances revealed mild deficits related to the excitotoxic NMDA-induced lesion as compared to the sham procedure. Moreover, accelerated rotarod and Morris water maze acquisition performances also revealed deficits related to the surgery, i.e. observed in sham-operated as compared to control mice. NeuN staining revealed no striatal lesion in the sham and non-operated groups in contrast to the NMDA-injected group in which the volume of infarcted striatum was 2.4±0.3mm3. GFAP staining revealed a glial reaction in the lesioned striatum of NMDA animals and at the PBS injection site in sham animals. These results suggest that NMDA-induced excitotoxic lesion induces subtle long-term behavioural deficits in mice. Moreover, this study shows the importance of the sham group to investigate the behavioural deficits after excitotoxic lesion models in mice.

International audience; Systematic behavioral phenotyping of genetically modified mice is a powerful method with which to identify the molecular factors implicated in control of animal behavior, with potential relevance for research into neuropsychiatric disorders. A number of such disorders display sex differences, yet the use of female mice in phenotyping strategies has been a rare practice because of the potential variability related to the estrous cycle. We have now investigated the behavioral effects of the estrous cycle in a battery of behavioral tests in C57BL/6J and BALB/cByJ inbred strains of mice. Whereas the performance of BALB/cByJ female mice varied significantly depending on the phase of the estrous cycle in the open field, tail flick and tail suspension tests, the behavior of C57BL/6J females, with the exception of the tail suspension performance, remained stable across all four phases of the estrous cycle in all of the tests including open field, rotarod, startle reflex and pre-pulse inhibition, tail flick and hot plate. We also found that irrespective of the estrous cycle, the behavior of C57BL/6J females was different from that of BALB/cByJ groups in all of the behavioral paradigms. Such strain differences were previously reported in male comparisons, suggesting that the same inter-group differences can be revealed by studying female or male mice. In addition, strain differences were evident even for behaviors that were susceptible to estrous cycle modulations, although their detection might necessitate the constitution of large experimental groups.

International audience; The purpose of this experiment was to determine whether a faded knowledge of results (KR) frequency during observation of a model's performance enhanced error detection capabilities. During the observation phase, participants observed a model performing a timing task and received KR about the model's performance on each trial or on one of two trials. Delayed retention and transfer tests were used to assess the observer's ability to detect error in the model's performance and in the participant's performance while physically practicing the task. Results indicated a beneficial effect of a reduced KR frequency for performance stability and the ability to detect errors in both the model and the participant's own performance. The results suggest that aspects of the processing mechanism(s) developed in observational learning and related to KR are probably similar to those developed through physical practice.

International audience; While experimental studies in the monkey have shown that motor recovery after partial destruction of the hand motor cortex was based on adjacent motor reorganization, functional MRI (fMRI) studies with isolated primary motor cortical stroke have not yet been reported in humans. Based on experimental data, we designed a study to test if recovery after stroke within primary motor cortex (M1) was associated with reorganization within the surrounding motor cortex, i.e. the motor cortex was able to vicariate. Since motor recovery is time-dependent and might be inflected according to the tested task, the delay after stroke and two motor tasks were included in our design. We examined four patients with one ischaemic stroke limited to M1, and four sex- and age-matched healthy controls in a temporally balanced prospective longitudinal fMRI study over three sessions

International audience; The authors investigated whether bandwidth knowledge of results (KR) during observation of a model's performance enhances motor skill learning. Following a pretest, 2 groups of participants (N = 28) observed a model practicing a timing task. The bandwidth group received KR about the model's performance only when his performance fell outside the criteria for a correct response. The yoked group received KR on the same trials as the bandwidth group did but were not told that the KR was only about incorrect performances. In that way, the authors avoided a confound between bandwidth and relative frequency effects on performance and learning. Following the observation phase, both groups of participants performed 10-min and 24-hr retention tests. Bandwidth KR enabled that group to reduce its performance variability and, to a lesser extent, to enhance its performance accuracy. The authors discuss the results with respect to the powerful effect of qualitative KR through observation.

International audience; OBJECTIVES: Comparatively little research has been conducted on right neglect after left brain damage. The authors sought to assess contralateral neglect in subacute left hemisphere stroke patients using a comprehensive test battery validated in a large control group after right hemisphere stroke. METHODS: Seventy-eight left hemisphere stroke patients were assessed. The test battery included a preliminary assessment of anosognosia and visual extinction, a clinical assessment of gaze orientation and personal neglect, and paper-and-pencil tests of spatial neglect in the peripersonal space. Only nonverbal tests were used. RESULTS: Drawing and cancellation tasks revealed neglect in 10 to 13% of patients. The combined battery was more sensitive than any single test alone. A total of 43.5% of patients showed some degree of neglect on at least one measure. Anatomic analyses showed that neglect was more common and severe when the posterior association cortex was damaged. CONCLUSIONS: The frequency of occurrence of right neglect was, as expected, much lower than that reported in a study using the same assessment battery in right brain damage stroke patients. Nevertheless, neglect was found in a substantial proportion of patients at a subacute stage, suggesting that it should be considered in the rehabilitation planning of left brain damage stroke patients.

International audience; Reorganization of motor execution and imagination networks was studied in six patients with unilateral dystonia secondary to a subcortical stroke and compared with seven control subjects using fMRI. Patients performed imagined and real auditory-cued hand movements. Movements of the dystonic hand resulted in overactivity in bilateral motor, premotor, and prefrontal cortex, insula, precuneus, and cerebellum, in parietal areas and the striatum contralateral to the lesion. Movements of the unaffected hand resulted in overactivity in bilateral preSMA, prefrontal, and parietal areas, insula and cerebellum, the ipsilateral premotor cortex and the contralateral striatum to the lesion. Mental representation of movements with each hand resulted in overactivity in bilateral parietal, premotor and prefrontal areas. These results suggest that execution and mental representation of movement are altered in these patients.

International audience; The authors examined whether reduced knowledge of results (KR) frequency during observation of a model's performance enhances learning. As they viewed a timing task, observers (n = 54) received KR about the model's performance on each trial (100% KR) or on 1 out of 3 trials (33% KR). Controls (n = 18) received only physical practice; they did not take part in the observation session. The authors also wanted to dissociate the guidance effect of KR during physical practice from the guidance role played by the representation acquired during observation. Therefore, following the observation phase, participants physically performed the task with either the same or a different KR frequency than that experienced during observation. The effects of observation and physical practice on learning were assessed in delayed retention tests. The beneficial effect of reduced KR frequency during observation continued for the following physical practice phases. Possible explanations as to why KR influences observational learning are discussed.

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

The ability of experts in motor skills requiring a fine postural control to keep a stable upright posture while facing the task of reinserting proprioceptive information was investigated. Seven expert gymnasts and seven experts in other non-gymnastics sports were asked to stand as immobile as possible in two conditions of vision and no-vision. Within a trial, ankle proprioceptive input was modified by means of tendon vibration of both antagonistic ankle muscles. Center of foot pressure (COP) displacements were recorded using a force platform. Contrasting with the non-gymnasts, the gymnasts were able to rapidly take advantage of the reinsertion of proprioceptive information to decrease their COP displacements. These results suggest that the efficiency of the integration process leading to the reweighting of sensory information can be significantly improved through a specific training.

International audience; Cognitive deficits are frequently associated with Duchenne muscular dystrophy (DMD). They might be due to a deficiency in the brain isoforms of the 427 kDa full-length dystrophin, and/or to altered expression of other C-terminal dystrophin-gene products (Dp71, Dp140) also found in brain. Mdx mice, which only lack full-length dystrophin in both muscle and brain, were previously shown to have moderate learning and memory deficits. In the present study, we investigated behavioral responses in mdx3cv mutants, which have altered expression of all the dystrophin-gene products. Contrary to the original mdx mice, mdx3cv mice showed enhanced anxiety-related behaviors and reduced locomotion as compared to control mice. Although those perturbations might be related to the lack in C-terminal dystrophins, they do not seem sufficient to induce strong learning deficits in this mutant. Indeed, we showed that mdx3cv mice may display similar or weaker deficits during the learning of a bar-pressing task, as compared to mdx mice. The relevance of the mdx3cv mutant as a model to study the cognitive deficits associated with DMD is discussed.

(1998). Attentional Demands and the Organization of Reaching Movements in Rock Climbing. Research Quarterly for Exercise and Sport: Vol. 69, No. 4, pp. 406-410.

The present experiment examined the development of programming interception of a ball's movement across three groups of children ages 6, 8, and 10 years, who were compared with adults. In an interception task we manipulated the subjects' preparation by using Rosenbaum's 1980 precuing procedure. Two levels of precued information were used concerning the effector specified (right or left arm) and the direction of the arm projection (outside or inside). We focused particularly on RT and response errors. Analysis indicated RT decreased across the age groups and errors decreased mainly in the nonprecued condition. A critical period in improvement might be at age 8 as children use precue information to program their movements as efficiently as adults. The duration of effector programming was similar for children and adults but was more precise for the older subjects. For children as well as for adults, the specification of direction occurs after movement initiation and not before.

Background Vascular risk factors are associated with increased risk of cognitive impairment and dementia, but their association with motor function, another key feature of aging, has received little research attention. We examined the association between trajectories of the Framingham general cardiovascular disease risk score (FRS) over midlife and motor function later in life. Methods A total of 5376 participants of the Whitehall II cohort study (29% women) who had up to four repeat measures of FRS between 1991–1993 (mean age = 48.6 years) and 2007–2009 (mean age = 65.4 years) and without history of stroke or coronary heart disease in 2007–2009 were included. Motor function was assessed in 2007–2009 through objective tests (walking speed, chair rises, balance, finger tapping, grip strength). We used age- and sex-adjusted linear mixed models. Results Participants with poorer performances for walking speed, chair rises, and balance in 2007–2009 had higher FRS concurrently and also in 1991–1993, on average 16 years earlier. These associations were robust to adjustment for cognition, socio-economic status, height, and BMI, and not explained by incident mobility limitation prior to motor assessment. No association was found with finger tapping and grip strength. Conclusions Cardiovascular risk early in midlife is associated with poor motor performances later in life. Vascular risk factors play an important and under-recognized role in motor function, independently of their impact on cognition, and suggest that better control of vascular risk factors in midlife may prevent physical impairment and disability in the elderly.