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Melanie A. Mason, Anne C. Russ, Ryan T. Tierney, and Jamie L. Mansell

takes human error out of the blood glucose equation. 6 The closed-loop control system, which eliminates the individual making insulin adjustments, was first approved by the U.S. Food and Drug Administration in 2016. 8 Closed-loop control systems, also known as an artificial pancreas, use a combination

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Leanna Ferrand and Slobodan Jaric

The purpose of this study was to explore the effects of handedness on coordination of grip (G) and load (L) forces in static bimanual manipulation tasks. Participants (N = 10) exerted various L profiles against an externally fixed hand-held device based on presumably open-loop and closed-loop neural control mechanisms, (i.e., mediated and not mediated, respectively, by sensory feedback). Average G/L ratio and the coupling of G and L (i.e., stability of the G/L ratio and correlation between G and L) were separately assessed in each hand. The results revealed a lower average G/L ratio in the non-dominant hand suggesting a more economical grip, while the indices of G and L coupling were similar in two hands. The dominant and non-dominant hand failed to reveal relative advantages in the tasks predominantly based on open- and closed-loop control mechanisms, respectively. We conclude that, due to the static nature of the tested tasks, the particular advantage of the non-dominant hand in G and L coordination could be in line with the recently proposed specialization of the non-dominant limb for control of position. However, the overall results are not in line with classic views of the prevailing open- closed-loop neural mechanisms in the control of the dominant and nondominant limb, respectively.

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Jennifer Campbell, Stephanie Rossit, and Matthew Heath

in conditions that manipulated the availability of visual cues during movement planning and control. Participants completed goal-directed reaches in which visual input was selectively available during movement planning (i.e., open-loop [OL]) or available during movement planning and execution (i.e., closed-loop

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Matthew Heath and David A. Westwood

We investigated whether a representation of a visual target can be stored in memory and used to support the online control of reaching movements. To distinguish between the use of a stored target representation for movement planning versus online control, we employed a novel movement environment in which participants could not fully plan their action in advance of movement initiation; that is, the spatial mapping between the movement of a computer mouse and the on-screen movement of a cursor was randomly varied from trial to trial. As such, participants were required to use online control to reach the target position. Reaches were examined in full-vision and three memory-dependent conditions (0, 2, and 5 s of delay). Absolute constant error did not accumulate between full-vision and brief delay trials (i.e., the 0-s delay), suggesting a stored representation of the visual target can be used for online control of reaching given a sufficiently brief delay interval. Longer delay trials (2 and 5 s) were less accurate and more variable than brief delay trials; however, the residual accuracy of these memory-dependent actions suggests that the motor system may have access to a stored representation of the visual target for online control processes for upwards of 5 s following target occlusion.

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Florian Van Halewyck, Ann Lavrysen, Oron Levin, Digby Elliott, and Werner F. Helsen

Older adults traditionally adapt their discrete aiming movements, thereby traveling a larger proportion of the movement under closed-loop control. As the beneficial impact of a physically active lifestyle in older age has been described for several aspects of motor control, we compared the aiming performance of young controls to active and sedentary older adults. To additionally determine the contribution of visual feedback, aiming movements were executed with and without saccades. Results showed only sedentary older adults adopted the typical movement changes, highlighting the impact of a physically active lifestyle on manual aiming in older age. In an attempt to reveal the mechanism underlying the movement changes, evidence for an age-related decline in force control was found, which in turn resulted in an adapted aiming strategy. Finally, prohibiting saccades did not affect older adults’ performance to a greater extent, suggesting they do not rely more on visual feedback than young controls.

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Rahman Davoodi and Gerald E. Loeb

Computer models of the neuromusculoskeletal systems can be used to study different aspects of movement and its control in humans and animals. SIMM with Dynamics Pipeline (Musculographics Inc., Chicago) and SD-Fast (Symbolic Dynamics Inc., Mountain View, CA) are software packages commonly used for graphic and dynamic simulation of movement in musculoskeletal systems. Building dynamic models with SIMM requires substantial C programming, however, which limits its use. We have developed Musculoskeletal Modeling in Simulink (MMS) software to convert the SIMM musculoskeletal and kinetics models to Simulink (Mathworks Inc., Natick, MA) blocks. In addition, MMS removes SIMM’s run-time constraints so that the resulting blocks can be used in simulations of closed-loop sensorimotor control systems.

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John F. Swigart, Arthur G. Erdman, and Patrick J. Cain

A new method for quantifying shoe cushioning durability was developed. This method used a computer-controlled, closed-loop materials testing system to subject the shoes to force-time profiles that were indicative of running. The change in the magnitude of the maximum energy absorbed by a shoe and the change in the magnitude of the energy balance of the shoe were quantified after the shoe had been worn running for a given distance. A shoe that changed very little in these quantities had a small energy wear factor and was deemed to have durable cushioning. The test method was roughly validated through comparison of three shoes of different midsole constructions with known relative durabilities. The shoes were tested at four simulated running speeds for energy properties when they were new and after they were run in for 161 km. The relative durabilities of the tested shoes were consistent with expectations based on the shoes' materials and constructions, showing that the new method has promise in predicting shoe cushioning durability, and thus more complete studies of the method may prove useful.

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Robert W. Christina

By 1967, motor control and learning researchers had adopted an information processing (IP) approach. Central to that research was understanding how movement information was processed, coded, stored, and represented in memory. It also was centered on understanding motor control and learning in terms of Fitts’ law, closed-loop and schema theories, motor programs, contextual interference, modeling, mental practice, attentional focus, and how practice and augmented feedback could be organized to optimize learning. Our constraints-based research from the 1980s into the 2000s searched for principles of “self-organization”, and answers to the degrees-of-freedom problem, that is, how the human motor system with so many independent parts could be controlled without the need for an executive decision maker as proposed by the IP approach. By 2007 we were thinking about where the IP and constraints-based views were divergent and complementary, and whether neural-based models could bring together the behavior and biological mechanisms underlying the processes of motor control and learning.

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to be between 70 and 180 mg/dl. a. True b. False 2. Moderate and vigorous exercise sessions increase the risk of hyperglycemia in individuals with Type 1 diabetes. a. True b. False 3. There is significant evidence supporting that the closed-loop control system keeps blood glucose in the ideal range

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Shani Batcir and Itshak Melzer

postural sway, including open- and closed-loop control mechanisms. The mean-square CoP displacement versus time interval was used to plot the linear SDA plots that were suggested to present two different sway behaviors, that is, mechanisms depending on the time interval of interest. In short time intervals