Motor imagery in amyotrophic lateral Sclerosis: An fMRI study of postural control

BACKGROUND: The functional reorganization of brain networks sustaining gait is poorly characterized in amyotrophic lateral sclerosis (ALS) despite ample evidence of progressive disconnection between brain regions. The main objective of this fMRI study is to assess gait imagery-specific networks in ALS patients using dynamic causal modeling (DCM) complemented by parametric empirical Bayes (PEB) framework. METHOD: Seventeen lower motor neuron predominant (LMNp) ALS patients, fourteen upper motor neuron predominant (UMNp) ALS patients and fourteen healthy controls participated in this study. Each subject performed a dual motor imagery task: normal and precision gait. The Movement Imagery Questionnaire (MIQ-rs) and imagery time (IT) were used to evaluate gait imagery in each participant. In a neurobiological computational model, the circuits involved in imagined gait and postural control were investigated by modelling the relationship between normal/precision gait and connection strengths. RESULTS: Behavioral results showed significant increase in IT in UMNp patients compared to healthy controls (P(corrected) < 0.05) and LMNp (P(corrected) < 0.05). During precision gait, healthy controls activate the model's circuits involved in the imagined gait and postural control. In UMNp, decreased connectivity (inhibition) from basal ganglia (BG) to supplementary motor area (SMA) and from SMA to posterior parietal cortex (PPC) is observed. Contrary to healthy controls, DCM detects no cerebellar-PPC connectivity in neither UMNp nor LMNp ALS. During precision gait, bilateral connectivity (excitability) between SMA and BG is observed in the LMNp group contrary to UMNp and healthy controls. CONCLUSIONS: Our findings demonstrate the utility of implementing both DCM and PEB to characterize connectivity patterns in specific patient phenotypes. Our approach enables the identification of specific circuits involved in postural deficits, and our findings suggest a putative excitatory–inhibitory imbalance. More broadly, our data demonstrate how clinical manifestations are underpinned by network-specific disconnection phenomena in ALS

Au Monaco Dance Forum, les bienfaits de la danse sont démontrés.

à veni

Incidence de la posture initiale sur la programmation de la marche (contrôle du centre des masses lors de l'initiation de la marche sur l'avant-pied)

Par rapport à un objectif vitesse, la progression du corps au cours de l'initiation de la marche (IM) résulte du contrôle des forces gravitaires par les forces musculaires et du choix des paramètres locomoteurs. Dans ce travail, nous utilisons le modèle d'analyse de l'IM pour comprendre l'incidence de la posture initiale sur la programmation de la marche: d'une part, chez le sujet sain à qui on impose une posture, talons décollés du sol et d'autre part, chez le sujet avec la Dystrophie Musculaire de Becker (BMD), qui présente fréquemment naturellement cette posture. Celle-ci a pour conséquence de réduire la base posturale, restreindre l'amplitude de recul du centre des pressions des pieds (CP) au cours des Ajustements Posturaux Anticipateurs (APA). En associant les techniques dynamique, électromyographique (EMG) et dynamométrique, nous mettons en évidence, dans chacune des phases de l'IM, des modifications mais aussi des invariances des paramètres biomécaniques et EMG. Le contrôle des forces gravitaires par les forces musculaires chez le sujet sain adoptant la posture, talons décollés du sol diffère de celui mis en évidence chez le sujet présentant la BMD. Cette différence de contrôle est à l'origine de la perturbation de la séquence motrice normalement observée. Chez le sujet adoptant la posture, talons décollés du sol comme chez le patient, des synergies musculaires autres que celles normalement observées assistent la mise en place de cette séquence motrice, dans le but de conserver des APA adéquats pour la progression. Ceux-ci préparent la configuration posturale pour le mouvement à venir, assistent la performance motrice et présentent des caractéristiques dépendant des paramètres de la posture et du mouvement. De plus, l'ajustement entre vitesse du centre de gravité et du CP traduit des adaptations du schéma corporel dynamique. La stratégie de modulation de la vitesse du CP permet de discerner un comportement locomoteur spécifique des contraintes posturales.According to a velocity objective, body progression during gait initiation results from a control of the gravity forces by the muscular forces and a choice of the locomotor parameters. In this study, we use a gait initiation analysis model in order to understand the incidence of the initial posture on gait programming: on one hand, on the healthy subject to whom a heel-off posture is imposed and on the other hand, on the subject with Becker Muscular Dystrophy (BMD), who naturally frequently displays this posture. This latter consequently reduces the postural basis, limits the centre of foot pressure (CP) backward shift during the Anticipatory Postural Adjustments (APA). Using dynamic, electromyographical (EMG) and dynamometric techniques, we show, in each of the gait initiation phases, some modifications but also some invariances of the biomechanical and EMG parameters. The control of the gravity forces by the muscular forces in the healthy subject, adopting the heel-off posture differs from the one displayed by the subject with BMD. This difference of control is at the origin of the perturbation on the motor sequence normally observed. In the healthy subject adopting the heel-off posture as well as in the patient, muscular synergies other than the ones normally observed assist the occurence of this motor sequence in order to preserve appropriate APA for progression. These prepare the postural configuration for the forthcoming movement, assist the motor performance and present characteristics in relation with the parameters of the posture and movement. Moreover, the adjustement between centre of gravity and CP velocities may represent adaptations of the dynamic body scheme. The strategy of CP velocity modulation allows to distinguish a locomotor behaviour specific to the postural constraints.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Does Somatosensory Loss Induce Adaptation of the Gait Initiation Process?

International audienceGait initiation (GI) is the transient period between posture and movement. Its central programming takes into account the environmental constraints as well as the constraints induced by the body itself. Patients with peripheral sensory neuropathies display a severe proprioceptive deficit leading to balance and gait impairments and rely on a variety of compensatory mechanisms and are known to be dependent on vision. GI was studied on eight healthy subjects and five patients in order to assess the effect of somatosensory loss on the different phases of GI, combined with a manipulation of the visual inputs. Our main hypothesis is that the proprioceptive deficit would induce an adaptation of the GI process, especially when modifying the lower part of peripheral vision. The results show that the pathology induces some adaptations of the GI process, characterized by a decrease of the motor performance (assessed by the maximal anteroposterior velocity of the center of gravity at the end of the first step), a decrease in the spatial parameters (assessed by the peak amplitude of the backward shift of the center of foot pressure during the anticipation phase and the length of the first step), and a non-modification of the temporal parameters (assessed by the duration of the anticipation phase and of the first step). The suppression of the lower part of peripheral vision has no effect on the GI process. The role of the lower part of peripheral vision seems therefore to be less critical for GI, than for balance and locomotion

Pelvic Floor Muscle Training for Urinary Incontinence with or without Biofeedback or Electrostimulation in Women: A Systematic Review

To determine the effectiveness of pelvic floor muscle training (PFMT) with or without biofeedback or electrostimulation in reducing urinary incontinence and pelvic floor muscle con-traction in non-pregnant women with urinary incontinence. Methods: The following electronic databases were searched: PubMed, Cochrane Central, ClinicalTrials.gov, EU Clinical Trials Register, and sources from NICE, FDA, EMA, and SMC (articles only in English, 2000&ndash;2021). Search terms were: urinary incontinence, pelvic floor muscle training or exercises, biofeedback, electrostimulation. We used the PRISMA statement (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) for this systematic review. Relevant articles were selected, data were extracted, and quality was assessed. Data were extracted in predesigned form, followed by narrative synthesis. Results: Following the search, 15 RCTs were retrieved using the strict inclusion and exclusion criteria, assessing 2441 non-pregnant women with urinary incontinence. Of the 15 studies, 7 were low risk, 5 were medium risk, and 3 were high-risk studies. Of the 2441 patients, 970 were in PFMT, 69 were in extracorporeal magnetic innervation (ExMi) or with PFMT + BF, 30 were in electrostimulation (ES), 21 were in whole body vibration training (WBVT), 23 were in pelvic floor muscle + abdominal muscle therapy (PFM + AMT), 326 were in PFMT + biofeedback, 93 were in vaginal cones (VC), 362 were in PFMT + education, 318 were in education, and 229 were in control groups. The most often measures employed were pad tests, bladder diary, and questionnaire on the quality of life. Stress, urge and mixed urinary incontinence were studied. In all RCT, PFMT significantly reduced urinary incontinence, essentially SIU and MUI, when compared with the control group before and after treatment. Overall, out of 997 PFMT or PFMT + education patients, 504 patients (50.5%) showed improvement in urinary incontinence, and 218 became continent (21.8%) (negative pad test). In total, 62% of patients significantly reduced their urinary incontinence or cured it and improved their pelvic floor muscle contraction. All other physiotherapist techniques also significantly reduced urinary leakages, e.g., vaginal cones, biofeedback, ExMI, and WBVT when compared with the control group. There were no significant differences between these methods in reducing the severity of urinary incontinence. Conclusion: PFMT alone or with bio-feedback or electrostimulation was effective in reducing urinary incontinence and improving pelvic floor muscle contraction. PFMT when compared with other interventions such as bio-feedback, VC, and WBVT did not show significant differences but was superior to the control group. RCT studies with similar parameters used for measuring the outcomes need to be included

Exploring the Effects of Kinesiological Awareness and Mental Imagery on Movement Intention in the Performance of Demi-Plié

International audienceThis study was designed to assess the ability of a practitioner intervention using kinesiological explanations and mental imagery techniques to optimize the performance of demi-plié in dancers. Seven professional female ballet dancers were involved in the study. Biomechanical and electromyographical parameters (maximum knee flexion, jump height, maximal vertical acceleration and its duration, ratio of sagittal acceleration variation, and ratio of muscle activity in four muscles of the lower limb) were analyzed before and after the practitioner intervention. Results demonstrated no significant difference in the depth of the demi-plié, nor in the height of the jump that followed, nor in the maximal vertical acceleration and its duration, leading to the suggestion that the technical potential of the dancers was preserved. Significant differences were found in the SEMG of the hamstrings during the demi-plié and the jump, implying that an improvement in the dynamic alignment of the dancers was present. A correlation was also found between the ratio of sagittal acceleration variation and the hamstring activity, suggesting that increased hamstring engagement produces decreased disruption of dynamic alignment. However, the intervention was not assimilated equally by all of the dancers

Is What We Think Is Happening Really Happening ? What Can Electromyography (EMG) Tell Us about How We Move ?

International audienceforthcomin