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Understanding the role of anti-gravity behaviour in fine motor control is crucial to achieving a unified theory of motor control. We compare speech from astronauts before and immediately after microgravity exposure to evaluate the role of anti-gravity posture during fine motor skills. Here we show a generalized lowering of vowel space after space travel, which suggests a generalized postural shift of the articulators. Biomechanical modelling of gravitational effects on the vocal tract supports this analysis—the jaw and tongue are pulled down in 1g, but movement trajectories of the tongue are otherwise unaffected. These results demonstrate the role of anti-gravity posture in fine motor behaviour and provide a basis for the unification of motor control models across domains. [ABSTRACT FROM AUTHOR]

Home advantage in professional sports is a widely accepted phenomenon despite the lack of any controlled experiments at the professional level. The return to play of professional sports during the COVID-19 pandemic presents a unique opportunity to analyze the hypothesized effect of home advantage in neutral settings. While recent work has examined the effect of COVID-19 restrictions on home advantage in European football, comparatively few studies have examined the effect of restrictions in the North American professional sports leagues. In this work, we infer the effect of and changes in home advantage prior to and during COVID-19 in the professional North American leagues for hockey, basketball, baseball, and American football. We propose a Bayesian multi-level regression model that infers the effect of home advantage while accounting for relative team strengths. We also demonstrate that the Negative Binomial distribution is the most appropriate likelihood to use in modelling North American sports leagues as they are prone to overdispersion in their points scored. Our model gives strong evidence that home advantage was negatively impacted in the NHL and NBA during their strongly restricted COVID-19 playoffs, while the MLB and NFL showed little to no change during their weakly restricted COVID-19 seasons. [ABSTRACT FROM AUTHOR]

Purpose: Functional inoperability in advanced oral cancer is difficult to assess preoperatively. To assess functions of lips and tongue, biomechanical models are required. Apart from adjusting generic models to individual anatomy, muscle activation patterns (MAPs) driving patient-specific functional movements are necessary to predict remaining functional outcome. We aim to evaluate how volunteer-specific MAPs derived from surface electromyographic (sEMG) signals control a biomechanical face model. Methods: Muscle activity of seven facial muscles in six volunteers was measured bilaterally with sEMG. A triple camera set-up recorded 3D lip movement. The generic face model in ArtiSynth was adapted to our needs. We controlled the model using the volunteer-specific MAPs. Three activation strategies were tested: activating all muscles $$(\hbox {act}_\mathrm{all})$$ , selecting the three muscles showing highest muscle activity bilaterally $$(\hbox {act}_3)$$ -this was calculated by taking the mean of left and right muscles and then selecting the three with highest variance-and activating the muscles considered most relevant per instruction $$(\hbox {act}_\mathrm{rel})$$ , bilaterally. The model's lip movement was compared to the actual lip movement performed by the volunteers, using 3D correlation coefficients $$(\rho )$$ . Results: The correlation coefficient between simulations and measurements with $$\hbox {act}_\mathrm{rel}$$ resulted in a median $$\rho $$ of 0.77. $$\hbox {act}_3$$ had a median $$\rho $$ of 0.78, whereas with $$\hbox {act}_\mathrm{all}$$ the median $$\rho $$ decreased to 0.45. Conclusion: We demonstrated that MAPs derived from noninvasive sEMG measurements can control movement of the lips in a generic finite element face model with a median $$\rho $$ of 0.78. Ultimately, this is important to show the patient-specific residual movement using the patient's own MAPs. When the required treatment tools and personalisation techniques for geometry and anatomy become available, this may enable surgeons to test the functional results of wedge excisions for lip cancer in a virtual environment and to weigh surgery versus organ-sparing radiotherapy or photodynamic therapy. [ABSTRACT FROM AUTHOR]

Correction to: I Scientific Reports i https://doi.org/10.1038/s41598-023-34854-w, published online 22 May 2023 The original version of this Article contained an error. In the Discussion section, "In the present study, astronauts spent between 10 and 4 days aboard the ISS, much lower than the 90 day threshold necessary to achieve deep adaptation." now reads: "In the present study, astronauts spent between 10 to 14 days aboard the ISS, much lower than the 90 day threshold necessary to achieve deep adaptation.". [Extracted from the article]

Purpose: It is well established that posterior spinal surgery results in damage to the paraspinal musculature. The effects of such iatrogenic changes on spinal loading have not been previously investigated, particularly at levels adjacent to a spinal fusion. Therefore, the objective of this study was to investigate the effect of simulated muscle damage on post-operative spinal loading at the adjacent levels to a spinal fusion during upright postures using a mathematical model.Methods: A musculoskeletal model of the spine using ArtiSynth with 210 muscle fascicles was used to predict spinal loading in an upright posture. The loading at L1-L2 and L5-S1 were estimated before and after simulated paraspinal muscle damage (i.e., removal of muscle attachments at L2-L5) along the lumbar spine, both with a spinal fusion at L2-L5 and without a spinal fusion.Results: The axial compressive forces at the adjacent levels increased after simulated muscle damage, with the largest changes being at the rostral level (78 % increase in presence of spinal fusion; 73 % increase without spinal fusion) compared to the caudal level (41 % in presence of fusion and 32 % without fusion). Shear forces increased in a similar manner at both the rostral and caudal levels. These changes in loading were due to a redistribution of muscle activity from the local lumbar to the global spinal musculature.Conclusions: The results suggest that the paraspinal muscles of the lumbar spine play an important role in adjacent segment loading of a spinal fusion, independent of the presence of rigid spinal instrumentation. [ABSTRACT FROM AUTHOR]

Musculoskeletal simulation has become an essential tool for understanding human locomotion and movement disorders. Muscle-actuated simulations require methods that continuously compute musculotendon paths, their lengths, and their rates of length change to determine muscle forces, moment arms, and the resulting body and joint loads. Musculotendon paths are often modeled as locally length minimizing curves that wrap frictionlessly over moving obstacle surfaces representing bone and tissue. Biologically accurate wrapping surfaces are complex, and a single muscle path may wrap around many obstacles. However, state-of-the-art muscle wrapping methods are either limited to analytical results for a pair of simple surfaces, or they are computationally expensive. In this paper, we introduce the Natural Geodesic Variation (NGV) method for the fast and accurate computation of a musculotendon's shortest path across an arbitrary number of general smooth wrapping surfaces, and an explicit formula for the path's exact rate of length change. The total path is regarded as a concatenation of straight-line segments between local surface geodesics, where each geodesic is naturally parameterized by its starting point, direction, and length. The shortest path is computed by finding the root of a global path-error constraint equation that enforces that the geodesics connect collinearly with adjacent straight-line segments. High computational speed is achieved using Newton's method to zero the path error, with an explicit, banded Jacobian that maps natural variations of the geodesic parameters to path-error variations. Three simulation benchmarks demonstrate that the NGV method computes high-precision solutions for path length and rate of length change, allows for wrapping over biologically accurate surfaces, and is capable of simulating muscle paths over hundreds of surfaces in real time. We thus believe the NGV method will facilitate the development of more accurate yet very efficient musculoskeletal models. [ABSTRACT FROM AUTHOR]