Interaction attention-motricité chez le sujet sain et parkinsonien : mécanismes et modulation

Gait initiation is a motor program not fully automatized which varies according to attentional capacities. Motor deficits and cognitive decline, including attention, develops with ageing and Parkinson’s disease and may lead to risk of falls.The main objective was to better characterize and modulate the interaction between step initiation and visuospatial attention at behavioral and cortical level.We first produced a state of the art in the literature on dual tasks’ paradigms with gait initiation and a cognitive task. A very limited number of studies on this topic were carried out despite a promising potential for risk of falls’ prediction.To analyze the attention-locomotion interplay, we tested a paradigm combining the Attention Network Test with gait initiation on young subjects. Accordingly, the interaction could be characterized.After validating abnormal coupling between initial posture, preparation phases and gait execution in patients with freezing of gait, the attention-step initiation interplay was investigated. An impairment in executive control does exist, but without any specific repercussion on step initiation.A functional connectivity EEG analysis at resting state and during an attentional task allowed to investigate further cognitive decline in patients with freezing of gait. An overdependence on the environment as potential compensatory mechanism was observed.Eventually, a research protocol that aims to modulate the attention-locomotion interaction via a combination of structured cognitive training and methylphenidate treatment was initiated.L’initiation de la marche est un programme moteur qui n’est pas entièrement automatisé et varie selon les capacités attentionnelles. Des troubles moteurs et un déclin cognitif, notamment attentionnel, se développent avec le vieillissement et la maladie de Parkinson, ce qui entraîne un risque de chute.L’objectif principal a été de mieux caractériser et de moduler l’interaction entre initiation du pas et attention visuo-spatiale au niveau comportemental et cortical.Nous avons d’abord fait un état des lieux de la littérature sur les paradigmes de double tâche avec initiation de la marche et tâche cognitive. Ceux-ci ont été peu étudiés malgré un potentiel prometteur pour la prédiction du risque de chute.Pour analyser l’interaction attention-locomotion, nous avons testé un paradigme combinant l’Attention Network Test avec l’initiation du pas chez de jeunes adultes. L’interaction a pu être caractérisée.Après validation du couplage anormal entre posture initiale et phases de préparation et exécution de la marche chez les patients avec enrayage cinétique, l’interaction attention-initiation du pas y a été étudiée. Un défaut de contrôle exécutif existe, mais sans répercussion spécifique sur l’initiation du pas.Une analyse de la connectivité fonctionnelle EEG à l’état de repos et lors d’une tâche attentionnelle a permis d’investiguer davantage le déclin cognitif chez les patients avec enrayage cinétique. Une sur-dépendance à l’environnement comme potentiel mécanisme compensateur a été observée.Enfin, un protocole de recherche qui vise à moduler l’interaction attention-locomotion via la combinaison d’un entraînement cognitif structuré et un traitement au méthylphénidate a été entamé

Interaction attention-motricity in healthy subjects and people with Parkinson’s disease : mechanisms and modulation

L’initiation de la marche est un programme moteur qui n’est pas entièrement automatisé et varie selon les capacités attentionnelles. Des troubles moteurs et un déclin cognitif, notamment attentionnel, se développent avec le vieillissement et la maladie de Parkinson, ce qui entraîne un risque de chute.L’objectif principal a été de mieux caractériser et de moduler l’interaction entre initiation du pas et attention visuo-spatiale au niveau comportemental et cortical.Nous avons d’abord fait un état des lieux de la littérature sur les paradigmes de double tâche avec initiation de la marche et tâche cognitive. Ceux-ci ont été peu étudiés malgré un potentiel prometteur pour la prédiction du risque de chute.Pour analyser l’interaction attention-locomotion, nous avons testé un paradigme combinant l’Attention Network Test avec l’initiation du pas chez de jeunes adultes. L’interaction a pu être caractérisée.Après validation du couplage anormal entre posture initiale et phases de préparation et exécution de la marche chez les patients avec enrayage cinétique, l’interaction attention-initiation du pas y a été étudiée. Un défaut de contrôle exécutif existe, mais sans répercussion spécifique sur l’initiation du pas.Une analyse de la connectivité fonctionnelle EEG à l’état de repos et lors d’une tâche attentionnelle a permis d’investiguer davantage le déclin cognitif chez les patients avec enrayage cinétique. Une sur-dépendance à l’environnement comme potentiel mécanisme compensateur a été observée.Enfin, un protocole de recherche qui vise à moduler l’interaction attention-locomotion via la combinaison d’un entraînement cognitif structuré et un traitement au méthylphénidate a été entamé.Gait initiation is a motor program not fully automatized which varies according to attentional capacities. Motor deficits and cognitive decline, including attention, develops with ageing and Parkinson’s disease and may lead to risk of falls.The main objective was to better characterize and modulate the interaction between step initiation and visuospatial attention at behavioral and cortical level.We first produced a state of the art in the literature on dual tasks’ paradigms with gait initiation and a cognitive task. A very limited number of studies on this topic were carried out despite a promising potential for risk of falls’ prediction.To analyze the attention-locomotion interplay, we tested a paradigm combining the Attention Network Test with gait initiation on young subjects. Accordingly, the interaction could be characterized.After validating abnormal coupling between initial posture, preparation phases and gait execution in patients with freezing of gait, the attention-step initiation interplay was investigated. An impairment in executive control does exist, but without any specific repercussion on step initiation.A functional connectivity EEG analysis at resting state and during an attentional task allowed to investigate further cognitive decline in patients with freezing of gait. An overdependence on the environment as potential compensatory mechanism was observed.Eventually, a research protocol that aims to modulate the attention-locomotion interaction via a combination of structured cognitive training and methylphenidate treatment was initiated

Cortical Oscillations during Gait: Wouldn’t Walking Be So Automatic?

International audienceGait is often considered as an automatic movement but cortical control seems necessary to adapt gait pattern with environmental constraints. In order to study cortical activity during real locomotion, electroencephalography (EEG) appears to be particularly appropriate. It is now possible to record changes in cortical neural synchronization/desynchronization during gait. Studying gait initiation is also of particular interest because it implies motor and cognitive cortical control to adequately perform a step. Time-frequency analysis enables to study induced changes in EEG activity in different frequency bands. Such analysis reflects cortical activity implied in stabilized gait control but also in more challenging tasks (obstacle crossing, changes in speed, dual tasks…). These spectral patterns are directly influenced by the walking context but, when analyzing gait with a more demanding attentional task, cortical areas other than the sensorimotor cortex (prefrontal, posterior parietal cortex, etc.) seem specifically implied. While the muscular activity of legs and cortical activity are coupled, the precise role of the motor cortex to control the level of muscular contraction according to the gait task remains debated. The decoding of this brain activity is a necessary step to build valid brain–computer interfaces able to generate gait artificially

Initial center of pressure position prior to anticipatory postural adjustments during gait initiation in people with Parkinson's disease with freezing of gait

Introduction: Freezing of gait (FOG) in Parkinson's disease (PD) is associated with an altered posture during quiet stance as well as an impaired preparation and execution of the gait initiation process. We aimed to investigate whether an altered initial posture impacts anticipatory postural adjustments (APAs) and first-step execution during gait initiation in people with PD with FOG (PD + FOG).Methods: Twenty-seven PD+FOG, 30 PD patients without FOG and 27 age-matched healthy controls performed self-generated gait initiation. Initial mean center of pressure (COP) position prior to APA onset, characteristics of APAs and features of first-step execution were investigated.Results: Contrarily to controls, PD patients showed a COP that was initially positioned more towards the stance leg (p = 0.007). Moreover, significantly smaller backward COP shift, longer duration of swing-foot unloading phase, and lower first-step length and velocity characterized PD+FOG compared to controls. While size and duration of backward COP shift during APA and lateral COP shift during the unloading phase were main predictors of first-step length and velocity in all groups, the medio-lateral shift of the initial COP position in PD+FOG was a main predictor of first-step execution (β = −0.191, p = 0.001 for velocity).Conclusion: In PD+FOG, the more the COP was initially positioned towards the stance foot, the slower and shorter the first step. The initial medio-lateral COP position may be a compensatory strategy to address postural instability of PD+FOG. A specific training regarding postural control prior to gait preparation and execution could improve functional mobility in PD+FOG

The interaction between cognition and motor control: A theoretical framework for dual-task interference effects on posture, gait initiation, gait and turning

Studies of dual tasks (i.e. situations during which an individual performs two tasks simultaneously) and the subsequent inter-task interference have shown that locomotion and posture involves motor and cognitive components. Dual tasks therefore constitute a promising avenue for improving the diagnosis, prevention and management of falls or cognitive impairment in populations at risk. However, tackling these major public health concerns with dual-task interventions requires a better understanding of the mechanisms underlying dual-task interference. In this context, we review (i) the main dual-task theories proposed to date and (ii) the factors that can influence dual-task interference effects in healthy young individuals and might therefore explain the current lack of consensus on the mechanisms of dual tasks. We also consider cognitive-motor dual tasks in which the motor task is a less frequently studied transition movement (such as gait initiation or turning), rather than only the often-studied gait and posture tasks. In general, the review focuses on the behavioral effects of dual tasking

Motor Preparation of Step Initiation: Error-related Cortical Oscillations

"European Union (EU)" - "Horizon 2020" - "MSCA-ITN-ETN" - "Keep Control" - "Grant number 721577"Gait initiation can vary as a function of the available and engaged attentional resources. Conflict resolution can disrupt movement preparation and lead to ‘‘errors” in motor programming. These ‘‘errors” are physiologically useful by enabling us to adapt our motor behavior to situations with conflicting information. The objective of the present study was to analyze the patterns of cortical activation associated with motor programming errors and the corresponding error corrections. Incongruent flankers around a target arrow were used to trigger errors in anticipatory postural adjustments (APAs) prior to gait initiation; i.e. perturbed motor programming but normal execution. Thirty healthy adults performed a gait initiation task. The event-related potentials (ERPs) and event-related desynchronization (ERD) after target presentation were analyzed according to the presence or absence of an APA error. The ERP was similar in both conditions, except that the Ne and P300 peak latencies were longer for APA errors. Motor programming errors during gait initiation were characterized by longer, less intense low-beta-band ERD over the sensorimotor cortex and alpha ERS followed by stronger alpha ERD during errors. APA errors were associated with a specific alpha/beta oscillation profile over the sensorimotor cortex; these beta oscillations might be sensitive markers of non-conscious motor error and correction monitoring

The frontostriatal subtype of mild cognitive impairment in Parkinson's disease, but not the posterior cortical one, is associated with specific EEG alterations

BACKGROUND: The 'dual syndrome' hypothesis states that two cognitive subtypes can be distinguished in mild cognitive impairment in Parkinson's disease (PD-MCI): a frontostriatal one, characterized by attentional and/or executive deficits, and a posterior cortical one, characterized by visuospatial, memory and/or language deficits. The latter type has been associated with a higher risk of earlier development of PD dementia. The functional bases of these subtypes remain partly unknown. OBJECTIVE: To identify EEG modifications associated with PD-MCI subtypes. METHODS: 75 non-demented PD patients underwent a comprehensive neuropsychological assessment and a high-density EEG. They were classified as having normal cognition (PD-NC; n = 37), PD-MCI with a frontostriatal subtype (PD-FS; n = 11) or PD-MCI with a posterior cortical subtype (PD-PC; n = 27). Two EEG analyses were performed: (a) spectral powers quantification and (b) functional connectivity analysis. RESULTS: PD-FS patients displayed spectral and functional EEG alterations, namely (a) higher powers in the theta and delta bands, (b) lower powers in the beta2 band and (c) lower functional connectivity in the beta2 band compared to PD-NC and PD-PC patients. These alterations were mainly located in the frontal, limbic and parietal regions. There were no significant differences between PD-NC and PD-PC. CONCLUSION: EEG alterations previously reported in PD-MCI may only concern the frontostriatal subtype, and not the posterior-cortical subtype. This provides evidence for the dual syndrome hypothesis and emphasizes the importance of identifying PD-MCI subtypes. It also shows the promising potential of EEG to discriminate between PD-MCI subtypes