72 research outputs found

    The perceptual shaping of anticipatory actions

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    Humans display anticipatory motor responses to minimize the adverse effects of predictable perturbations. A widely accepted explanation for this behaviour relies on the notion of an inverse model that, learning from motor errors, anticipates corrective responses. Here, we propose and validate the alternative hypothesis that anticipatory control can be realized through a cascade of purely sensory predictions that drive the motor system, reflecting the causal sequence of the perceptual events preceding the error. We compare both hypotheses in a simulated anticipatory postural adjustment task. We observe that adaptation in the sensory domain, but not in the motor one, supports the robust and generalizable anticipatory control characteristic of biological systems. Our proposal unites the neurobiology of the cerebellum with the theory of active inference and provides a concrete implementation of its core tenets with great relevance both to our understanding of biological control systems and, possibly, to their emulation in complex artefacts

    Annotated Bibliography: Anticipation

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    THE ONENESS OF POSTURE AND VOLUNTARY MOVEMENT

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    During my PhD studies, I have dealt with several aspects of the relationship between posture and voluntary movement. In particular, the main subject of my work has been to analyze the functional role of the Anticipatory Postural Adjustments (APAs) within the motor act and how these are programmed by the central nervous system. In the past literature, it has been described that APAs are unconscious muscular activities aimed to maintain the equilibrium of the whole body (Massion 1992). The role of the APAs has been first disclosed in movements involving relatively large masses, such as an upper-limb flexion (see for a review, Bouisset and Do 2008). In this case, the shoulder flexion may displace the projection of the center of mass to ground, eventually causing an imbalance of the whole body. Therefore, in order to counteract such a perturbation, the recruitment of the prime mover (Anterior Deltoid) is normally preceded by a specific pattern of EMG activities, defined as APAs, developing in the lower limbs, the hips and the trunk. This inter-limb APA chain is thus able to induce a forward displacement which prevents the backward perturbation caused by the focal movement. More recently, Caronni and Cavallari (2009a) demonstrated that an APA chain also develop for very simple movements such as a finger flexion, in which small masses are involved and in which the whole-body equilibrium is not threatened. Indeed, the index-finger flexion, performed with the hand prone, has been found being preceded by an excitatory burst in Triceps Brachii, while Biceps Brachii and Anterior Deltoid showed a concomitant inhibition. This APA pattern, shaped in the primary motor cortex (Caronni and Cavallari 2009b), contrasts the flexion of elbow and shoulder induced by the upward perturbation that the index-finger flexion causes on the metacarpo-phalangeal joint. Caronni and Cavallari papers (2009a, b) contributed to arise three questions: i) do inter-limb and intra-limb APAs share similar control mechanisms? If yes, ii) what is the functional role of intra-limb APAs, since it is hard to keep considering intra-limb APAs simply as a counter-perturbation aiming to maintain the whole-body equilibrium and iii) does the prime mover recruitment and its associated postural adjustments result from two different central commands, as classically proposed (Babinski 1899; Hess 1943; Cordo and Nashner 1982; Brown and Frank 1987) or are they both controlled by a unique motor command, as suggested by more recent evidences (Aruin and Latash 1995; Petersen et al. 2009; Caronni and Cavallari 2009b; Leonard et al. 2011)? Aim of the present thesis is to shed further light on these questions with the specific target of investigating a possible role of APAs in refining movement accuracy and demonstrating the oneness of the motor command for both anticipatory postural adjustments (APAs) and prime mover recruitment. Thus, I will illustrate: i) the key role of a properly-tailored APA chain on prime mover recruitment in refining movement accuracy, ii) the superposition of the neural network responsible for controlling the voluntary movement and the APAs, focusing on Supplementary Motor Area and Cerebellum, iii) the disruption of both the postural chain and the prime mover recruitment after a period of immobilization and iv) the APAs adaptation to the intended movement, i.e. the expected perturbation. These observations have been already published or are at this moment submitted to publication. The thesis has been divided in four sections: 1) the Introduction, which includes a review on the existing literature on inter- and intra-limb APAs, and explains my working hypothesis; 2) the Experimental Procedure, which describes how data were collected and analyzed.; 3) the collection of the original papers, and finally 4) the Conclusion, in which I will explain the interpretation of the present results and develop possible conclusions, with special regards on the relationship between postural and prime mover command

    Applications of EMG in Clinical and Sports Medicine

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    This second of two volumes on EMG (Electromyography) covers a wide range of clinical applications, as a complement to the methods discussed in volume 1. Topics range from gait and vibration analysis, through posture and falls prevention, to biofeedback in the treatment of neurologic swallowing impairment. The volume includes sections on back care, sports and performance medicine, gynecology/urology and orofacial function. Authors describe the procedures for their experimental studies with detailed and clear illustrations and references to the literature. The limitations of SEMG measures and methods for careful analysis are discussed. This broad compilation of articles discussing the use of EMG in both clinical and research applications demonstrates the utility of the method as a tool in a wide variety of disciplines and clinical fields

    Multimodal Sensory Integration for Perception and Action in High Functioning Children with Autism Spectrum Disorder

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    Movement disorders are the earliest observed features of autism spectrum disorder (ASD) present in infancy. Yet we do not understand the neural basis for impaired goal-directed movements in this population. To reach for an object, it is necessary to perceive the state of the arm and the object using multiple sensory modalities (e.g. vision, proprioception), to integrate those sensations into a motor plan, to execute the plan, and to update the plan based on the sensory consequences of action. In this dissertation, I present three studies in which I recorded hand paths of children with ASD and typically developing (TD) controls as they grasped the handle of a robotic device to control a cursor displayed on a video screen. First, participants performed discrete and continuous movements to capture targets. Cursor feedback was perturbed from the hand\u27s actual position to introduce visuo-spatial conflict between sensory and proprioceptive feedback. Relative to controls, children with ASD made greater errors, consistent with deficits of sensorimotor adaptive and strategic compensations. Second, participants performed a two-interval forced-choice discrimination task in which they perceived two movements of the visual cursor and/or the robot handle and then indicated which of the two movements was more curved. Children with ASD were impaired in their ability to discriminate movement kinematics when provided visual and proprioceptive information simultaneously, suggesting deficits of visuo-proprioceptive integration. Finally, participants made goal-directed reaching movements against a load while undergoing simultaneous functional magnetic resonance imaging (MRI). The load remained constant (predictable) within an initial block of trials and then varied randomly within four additional blocks. Children with ASD exhibited greater movement variability compared to controls during both constant and randomly-varying loads. MRI analysis identified marked differences in the extent and intensity of the neural activities supporting goal-directed reaching in children with ASD compared to TD children in both environmental conditions. Taken together, the three studies revealed deficits of multimodal sensory integration in children with ASD during perception and execution of goal-directed movements and ASD-related motor performance deficits have a telltale neural signature, as revealed by functional MR imaging

    Biofeedback Based Physical Rehabilitation in Parkinson's Disease Aimed at Self-Enhancement

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    Parkinson’s disease (PD) is a progressive neuromotor disorder that results in a progressive deterioration of balance and motor abilities with a consequent increase of the risk of falls and a reduction of quality of life. Physical therapy revealed to be fit for the symptomatic treatment of the disease and the adoption of biofeedback signals showed to be effective in prolonging the benefits of the therapy. Thus, this doctoral project has been designed to assess the benefits that wearable technologies for biofeedback generation could have in physical therapy. To further improve the developed biofeedback-based system, the assessment of new methods for the objective evaluation of balance control was included into the study. The dissertation is divided into three different set of studies, respectively aimed at: 1) presenting new wearable systems specifically designed for biofeedback-based rehabilitation; 2) assessing proprioceptive impairments in PD subjects through the adoption of a robotic platform to destabilize the base of support; 3) discussing new methods for the evaluation of balance preceding the execution of voluntary movements. The efficacy of the main proposed solution was assessed in a 6-months RCT study by comparison of subjects with PD trained with the biofeedback system and patients that received usual care. Both clinical and instrumental outcomes supported the higher efficacy of the biofeedback-based approach. The developed instrumented tests showed good sensitivity in discriminating patients and in detecting changes induced by physical therapy. The results reported in this thesis lead to the conclusion that the adoption of biofeedback based physical rehabilitation systems is promising in the treatment of Parkinson’s disease. The availability of a set of fast, easy-to-manage tests for the evaluation of balance and motor control might be useful in the design of home-delivered, user-tailored exercises for both healthy elderly and neurological subjects

    Human inspired humanoid robots control architecture

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    This PhD Thesis tries to present a different point of view when talking about the development of control architectures for humanoid robots. Specifically, this Thesis is focused on studying the human postural control system as well as on the use of this knowledge to develop a novel architecture for postural control in humanoid robots. The research carried on in this thesis shows that there are two types of components for postural control: a reactive one, and other predictive or anticipatory. This work has focused on the development of the second component through the implementation of a predictive system complementing the reactive one. The anticipative control system has been analysed in the human case and it has been extrapolated to the architecture for controlling the humanoid robot TEO. In this way, its different components have been developed based on how humans work without forgetting the tasks it has been designed for. This control system is based on the composition of sensorial perceptions, the evaluation of stimulus through the use of the psychophysics theory of the surprise, and the creation of events that can be used for activating some reaction strategies (synergies) The control system developed in this Thesis, as well as the human being does, processes information coming from different sensorial sources. It also composes the named perceptions, which depend on the type of task the postural control acts over. The value of those perceptions is obtained using bio-inspired evaluation techniques of sensorial inference. Once the sensorial input has been obtained, it is necessary to process it in order to foresee possible disturbances that may provoke an incorrect performance of a task. The system developed in this Thesis evaluates the sensorial information, previously transformed into perceptions, through the use of the “Surprise Theory”, and it generates some events called “surprises” used for predicting the evolution of a task. Finally, the anticipative system for postural control can compose, if necessary, the proper reactions through the use of predefined movement patterns called synergies. Those reactions can complement or substitute completely the normal performance of a task. The performance of the anticipative system for postural control as well as the performance of each one of its components have been tested through simulations and the application of the results in the humanoid robot TEO from the RoboticsLab research group in the Systems Engineering and Automation Department from the Carlos III University of Madrid. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Esta Tesis Doctoral pretende aportar un punto de vista diferente en el desarrollo de arquitecturas de control para robots humanoides. En concreto, esta Tesis se centra en el estudio del sistema de control postural humano y en la aplicación de este conocimiento en el desarrollo de una nueva arquitectura de control postural para robots humanoides. El estudio realizado en esta Tesis pone de manifiesto la existencia de una componente de control postural reactiva y otra predictiva o anticipativa. Este trabajo se ha centrado en el desarrollo de la segunda componente mediante la implementación de un sistema predictivo que complemente al sistema reactivo. El sistema de control anticipativo ha sido estudiado en el caso humano y extrapolado para la arquitectura de control del robot humanoide TEO. De este modo, sus diferentes componentes han sido desarrollados inspirándose en el funcionamiento humano y considerando las tareas para las que dicho robot ha sido concebido. Dicho sistema está basado en la composición de percepciones sensoriales, la evaluación de los estímulos mediante el uso de la teoría psicofísica de la sorpresa y la generación de eventos que sirvan para activar estrategias de reacción (sinergias). El sistema de control desarrollado en esta Tesis, al igual que el ser humano, procesa información de múltiples fuentes sensoriales y compone las denominadas percepciones, que dependen del tipo de tarea sobre la que actúa el control postural. El valor de estas percepciones es obtenido utilizando técnicas de evaluación bioinspiradas de inferencia sensorial. Una vez la entrada sensorial ha sido obtenida, es necesario procesarla para prever posibles perturbaciones que puedan ocasionar una incorrecta realización de una tarea. El sistema desarrollado en esta Tesis evalúa la información sensorial, previamente transformada en percepciones, mediante la ‘Teoría de la Sorpresa’ y genera eventos llamados ‘sorpresas’ que sirven para predecir la evolución de una tarea. Por último, el sistema anticipativo de control postural puede componer, si fuese necesario, las reacciones adecuadas mediante el uso de patrones de movimientos predefinidos llamados sinergias. Dichas reacciones pueden complementar o sustituir por completo la ejecución normal de una tarea. El funcionamiento del sistema anticipativo de control postural y de cada uno de sus componentes ha sido probado tanto por medio de simulaciones como por su aplicación en el robot humanoide TEO del grupo de investigación RoboticsLab en el Departamento de Ingeniería de Sistemas y Automática de la Universidad Carlos III de Madrid

    Proceedings SIAMOC 2019

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    Il congresso annuale della Società Italiana di Analisi del Movimento in Clinica, giunto quest'anno alla sua ventesima edizione, ritorna a Bologna, che già ospitò il terzo congresso nazionale nel 2002. Il legame tra Bologna e l'analisi del movimento è forte e radicato, e trova ampia linfa sia nel contesto accademico che nel ricco panorama di centri clinici d'eccellenza. Il congresso SIAMOC, come ogni anno, è l’occasione per tutti i professionisti dell’ambito clinico, metodologico ed industriale di incontrarsi, presentare le proprie ricerche e rimanere aggiornati sulle più recenti innovazioni nell’ambito dell’applicazione clinica dei metodi di analisi del movimento. Questo ha contribuito, in questi venti anni, a fare avanzare sensibilmente la ricerca italiana nel settore, conferendole un respiro ed un impatto internazionale, e a diffonderne l'applicazione clinica per migliorare la valutazione dei disordini motori, aumentare l'efficacia dei trattamenti attraverso l'analisi quantitativa dei dati e una più focalizzata pianificazione dei trattamenti, ed inoltre per quantificare i risultati delle terapie correnti

    Proceedings SIAMOC 2019

    Get PDF
    Il congresso annuale della Società Italiana di Analisi del Movimento in Clinica, giunto quest'anno alla sua ventesima edizione, ritorna a Bologna, che già ospitò il terzo congresso nazionale nel 2002. Il legame tra Bologna e l'analisi del movimento è forte e radicato, e trova ampia linfa sia nel contesto accademico che nel ricco panorama di centri clinici d'eccellenza. Il congresso SIAMOC, come ogni anno, è l’occasione per tutti i professionisti dell’ambito clinico, metodologico ed industriale di incontrarsi, presentare le proprie ricerche e rimanere aggiornati sulle più recenti innovazioni nell’ambito dell’applicazione clinica dei metodi di analisi del movimento. Questo ha contribuito, in questi venti anni, a fare avanzare sensibilmente la ricerca italiana nel settore, conferendole un respiro ed un impatto internazionale, e a diffonderne l'applicazione clinica per migliorare la valutazione dei disordini motori, aumentare l'efficacia dei trattamenti attraverso l'analisi quantitativa dei dati e una più focalizzata pianificazione dei trattamenti, ed inoltre per quantificare i risultati delle terapie correnti
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