839 research outputs found
Testing the Ability to Represent and Control a Contact Force
No full textWhile the concept of force is solidly grounded in Newtonian mechanics, it is not known if it is also represented in a consistent way by our brains as they control interactions of the hand with external objects. For example, a force of 10Â N applied against different springs will cause different amounts of displacement. Are we able to represent 10 N in a way that is independent of the effects of applying such force to different objects? Here, we developed a simple method to address this question by engaging subjects in a task whose success depends critically upon the ability to exert a fixed force against different simulated springs. Our preliminary findings indicate that while this task is difficult, subjects learn after some training to exert the same force against different springs and in different directions
Reorganization of Finger Coordination Patterns During Adaptation to Rotation and Scaling of a Newly Learned Sensorimotor Transformation
No full text We examined how people organize redundant kinematic control variables (finger joint configurations) while learning to make goal-directed movements of a virtual object (a cursor) within a low-dimensional task space (a computer screen). Subjects participated in three experiments performed on separate days. Learning progressed rapidly on day 1, resulting in reduced target capture error and increased cursor trajectory linearity. On days 2 and 3, one group of subjects adapted to a rotation of the nominal map, imposed either stepwise or randomly over trials. Another group experienced a scaling distortion. We report two findings. First, adaptation rates and memory-dependent motor command updating depended on distortion type. Stepwise application and removal of the rotation induced a marked increase in finger motion variability but scaling did not, suggesting that the rotation initiated a more exhaustive search through the space of viable finger motions to resolve the target capture task than did scaling. Indeed, subjects formed new coordination patterns in compensating the rotation but relied on patterns established during baseline practice to compensate the scaling. These findings support the idea that the brain compensates direction and extent errors separately and in computationally distinct ways, but are inconsistent with the idea that once a task is learned, command updating is limited to those degrees of freedom contributing to performance (thereby minimizing energetic or similar costs of control). Second, we report that subjects who learned a scaling while moving to just one target generalized more narrowly across directions than those who learned a rotation. This contrasts with results from whole-arm reaching studies, where a learned scaling generalizes more broadly across direction than rotation. Based on inverse- and forward-dynamics analyses of reaching with the arm, we propose the difference in results derives from extensive exposure in reaching with familiar arm dynamics versus the novelty of the manual task. </jats:p
Utility and usability of a wearable system and progressive-challenge cued exercise program for encouraging use of the more involved arm at-home after stroke—a feasibility study with case reports
No full textBackground Understanding the role of adherence to home exercise programs for survivors of stroke is critical to ensure patients perform prescribed exercises and maximize effectiveness of recovery.Methods Survivors of hemiparetic stroke with impaired motor function were recruited into a 7-day study designed to test the utility and usability of a low-cost wearable system and progressive-challenge cued exercise program for encouraging graded-challenge exercise at-home. The wearable system comprised two wrist-worn MetaMotionR+ activity monitors and a custom smartphone app. The progressive-challenge cued exercise program included high-intensity activities (one repetition every 30 s) dosed at 1.5 h per day, embedded within 8 h of passive activity monitoring per day. Utility was assessed using measures of system uptime and cue response rate. Usability and user experience were assessed using well-validated quantitative surveys of system usability and user experience. Self-efficacy was assessed at the end of each day on a visual analog scale that ranged from 0 to 100.Results The system and exercise program had objective utility: system uptime was 92 +/- 6.9% of intended hours and the rate of successful cue delivery was 99 +/- 2.7%. The system and program also were effective in motivating cued exercise: activity was detected within 5-s of the cue 98 +/- 3.1% of the time. As shown via two case studies, accelerometry data can accurately reflect graded-challenge exercise instructions and reveal differentiable activity levels across exercise stages. User experience surveys indicated positive overall usability in the home settings, strong levels of personal motivation to use the system, and high degrees of satisfaction with the devices and provided training. Self-efficacy assessments indicated a strong perception of proficiency across participants (95 +/- 5.0).Conclusions This study demonstrates that a low-cost wearable system providing frequent haptic cues to encourage graded-challenge exercise after stroke can have utility and can provide an overall positive user experience in home settings. The study also demonstrates how combining a graded exercise program with all-day activity monitoring can provide insight into the potential for wearable systems to assess adherence to-and effectiveness of-home-based exercise programs on an individualized basis
Spatial and Temporal Influences on Discrimination of Vibrotactile Stimuli on The Arm
No full textBody–machine interfaces (BMIs) provide a non-invasive way to control devices. Vibrotactile stimulation has been used by BMIs to provide performance feedback to the user, thereby reducing visual demands. To advance the goal of developing a compact, multivariate vibrotactile display for BMIs, we performed two psychophysical experiments to determine the acuity of vibrotactile perception across the arm. The first experiment assessed vibration intensity discrimination of sequentially presented stimuli within four dermatomes of the arm (C5, C7, C8, and T1) and on the ulnar head. The second experiment compared vibration intensity discrimination when pairs of vibrotactile stimuli were presented simultaneously vs. sequentially within and across dermatomes. The first experiment found a small but statistically significant difference between dermatomes C7 and T1, but discrimination thresholds at the other three locations did not differ. Thus, while all tested dermatomes of the arm and hand could serve as viable sites of vibrotactile stimulation for a practical BMI, ideal implementations should account for small differences in perceptual acuity across dermatomes. The second experiment found that sequential delivery of vibrotactile stimuli resulted in better intensity discrimination than simultaneous delivery, independent of whether the pairs were located within the same dermatome or across dermatomes. Taken together, our results suggest that the arm may be a viable site to transfer multivariate information via vibrotactile feedback for body–machine interfaces. However, user training may be needed to overcome the perceptual disadvantage of simultaneous vs. sequentially presented stimuli
Supplemental Vibrotactile Feedback of Real-Time Limb Position Enhances Precision of Goal-Directed Reaching
No full textWe examined vibrotactile stimulation as a form of supplemental limb state feedback to enhance planning and ongoing control of goal-directed movements. Subjects wore a two-dimensional vibrotactile display on their nondominant arm while performing horizontal planar reaching with the dominant arm. The vibrotactile display provided feedback of hand position such that small hand displacements were more easily discriminable using vibrotactile feedback than with intrinsic proprioceptive feedback. When subjects relied solely on proprioception to capture visuospatial targets, performance was degraded by proprioceptive drift and an expansion of task space. By contrast, reach accuracy was enhanced immediately when subjects were provided vibrotactile feedback and further improved over 2 days of training. Improvements reflected resolution of proprioceptive drift, which occurred only when vibrotactile feedback was active, demonstrating that benefits of vibrotactile feedback are due, in part to its integration into the ongoing control of movement. A partial resolution of task space expansion persisted even when vibrotactile feedback was inactive, demonstrating that training with vibrotactile feedback also induced changes in movement planning. However, the benefits of vibrotactile feedback come at a cognitive cost. All subjects adopted a stereotyped strategy wherein they attempted to capture targets by moving first along one axis of the vibrotactile display and then the other. For most subjects, this inefficient approach did not resolve over two bouts of training performed on separate days, suggesting that additional training is needed to integrate vibrotactile feedback into the planning and online control of goal-directed reaching in a way that promotes smooth and efficient movement
On The Precision Of Markerless 3d Semantic Features: An Experimental Study On Violin Playing
No full textHuman motion analysis is an essential task in several domains and, depending on the application field, it requires different level of accuracy. In the motor control field it is commonly performed with motion capture systems and infrared markers that guarantee a high accuracy. However, these systems are expensive, cumbersome, and may induce bias. An alternative to marker-based technologies are image-based markerless systems, that are cheaper and do not affect the naturalness of the motion. Although their accuracy level seems to limit their use in motor control field, a thorough quantitative comparison with marker-based techniques does not appear to be available yet. We compare the estimates of a 3D image-based marker-less pipeline we propose, with a standard marker-based system; the analysis is carried out on a multi-sensor dataset acquired to study the motion of violin players. The results we obtain on the precision level are suggesting that marker-less systems may successfully track performances in real-world settings
Atividade antinociceptiva do sesquiterpeno drimanial isolado das cascas de Drimys Winteri (winteraceae): estudo do mecanismo de ação
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-Graduação em Farmacologia.O sesquiterpeno drimanial isolado das cascas da planta brasileira Drimys winteri, apresentou importante atividade antinociceptiva, quando administrado por via sistêmica, intraplantar, espinhal e supraespinhal em diferentes modelos de nocicepção em camundongos. Além disso, o drimanial, apresentou marcante atividade anti-hiperalgésica quando avaliado na hiperalgesia induzida pelo glutamato. Os experimentos realizados com agonistas e antagonistas seletivos, e com o auxílio da técnica de união específica (binding) sugerem que a atividade antinociceptiva causada pelo drimanial esta relacionada com uma interação com o sistema glutamatérgico, mais especificamente, via interação com receptores glutamatérgicos metabotrópicos. Os resultados do presente estudo também indicam que os receptores vanilóides parecem contribuir para a atividade antinociceptiva do sesquiterpene drimanial. Além disso, os resultados do presente estudo indicam que o drimanial não apresentou atividade antinociceptiva quando avaliado em modelos de nocicepção t~ermica, como o teste da placa-quente ou da retirada de cauda (tail-flick). Por outro lado, sua atividade antinociceptiva não foi revertida pelo pré-tratamento dos animais com naloxona (antagonista opióide não-seletivo) ou com PCPA (inibidor da síntese de seotonina). Dessa forma, a atividade antinociceptiva do composto drimanial não parece depender de uma interação direta ou indireta com os sistemas opióide e serotoninérgico. Estes resultados não só confirmam, mas também estendem os resultados anteriores descritos em nosso laboratório, que demonstram que ambos os sesquiterpenos presentes nas cascas da D. winteri , o poligodial e o drimanial, contribuem de maneira importante para o uso desta planta na medicina popular
Supplemental vibrotactile feedback control of stabilization and reaching actions of the arm using limb state and position error encodings
No full textAbstract Background Deficits of kinesthesia (limb position and movement sensation) commonly limit sensorimotor function and its recovery after neuromotor injury. Sensory substitution technologies providing synthetic kinesthetic feedback might re-establish or enhance closed-loop control of goal-directed behaviors in people with impaired kinesthesia. Methods As a first step toward this goal, we evaluated the ability of unimpaired people to use vibrotactile sensory substitution to enhance stabilization and reaching tasks. Through two experiments, we compared the objective and subjective utility of two forms of supplemental feedback – limb state information or hand position error – to eliminate hand position drift, which develops naturally during stabilization tasks after removing visual feedback. Results Experiment 1 optimized the encoding of limb state feedback; the best form included hand position and velocity information, but was weighted much more heavily toward position feedback. Upon comparing optimal limb state feedback vs. hand position error feedback in Experiment 2, we found both encoding schemes capable of enhancing stabilization and reach performance in the absence of vision. However, error encoding yielded superior outcomes - objective and subjective - due to the additional task-relevant information it contains. Conclusions The results of this study have established the immediate utility and relative merits of two forms of vibrotactile kinesthetic feedback in enhancing stabilization and reaching actions performed with the arm and hand in neurotypical people. These findings can guide future development of vibrotactile sensory substitution technologies for improving sensorimotor function after neuromotor injury in survivors who retain motor capacity, but lack proprioceptive integrity in their more affected arm
Survey findings
No full textPears, K.C., Miao, A.J., Burton, M., Green, B.L., Hatfield, B. & Scheidt, D. ; submitted to the Oregon Early Learning Division and Early Learning Council.Title from PDF cover (viewed on July 23, 2021)."The Partnership for Preschool Improvement Project (PPI) is a multi-year partnership between the Oregon Early Learning Division (ELD); researchers from OSLC Developments, Inc., Portland State University, and Oregon State University; Start Early (™); the University of Washington; and the Alliance for Early Success. PPI is funded by the Bill and Melinda Gates Foundation"--Page 2.This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
FANFARES ET DANCERIES DE LA RENAISSANCE / ENSEMBLE PHILHARMONIQUE DE PARIS ; Dir. DOUATTE (R.)
No full textTitre uniforme : [Galliard "battaglia" : 2 trp, cuivres]Comprend : GAILLARDE DE BATAILLE / SCHEIDT (S.) - BRANLE DE BOURGOGNE / Anonyme - BRANLE DE POITOU / GERVAISE (C.) - FANFARES DE CEREMONIES / SCHEIDT (S.) - AIR DE COUR / BOESSET (A. de...) - AIR DE COUR / TESSIER (Charles)BnF-Partenariats, Collection sonore - BelieveContient une table des matière
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