scholarly journals Evolution of a high-performance and functionally robust musculoskeletal system in salamanders

2020 ◽  
Vol 117 (19) ◽  
pp. 10445-10454 ◽  
Author(s):  
Stephen M. Deban ◽  
Jeffrey A. Scales ◽  
Segall V. Bloom ◽  
Charlotte M. Easterling ◽  
Mary Kate O’Donnell ◽  
...  
Keyword(s):  
Musculoskeletal System ◽  
High Performance ◽  
Neural Control ◽  
Animal Movement ◽  
Thermal Sensitivity ◽  
Emergent Properties ◽  
Plethodontid Salamanders ◽  
Elastic Systems ◽  
Extreme Performance ◽  
Muscle Contractile

The evolution of ballistic tongue projection in plethodontid salamanders—a high-performance and thermally robust musculoskeletal system—is ideal for examining how the components required for extreme performance in animal movement are assembled in evolution. Our comparative data on whole-organism performance measured across a range of temperatures and the musculoskeletal morphology of the tongue apparatus were examined in a phylogenetic framework and combined with data on muscle contractile physiology and neural control. Our analysis reveals that relatively minor evolutionary changes in morphology and neural control have transformed a muscle-powered system with modest performance and high thermal sensitivity into a spring-powered system with extreme performance and functional robustness in the face of evolutionarily conserved muscle contractile physiology. Furthermore, these changes have occurred in parallel in both major clades of this largest family of salamanders. We also find that high-performance tongue projection that exceeds available muscle power and thermal robustness of performance coevolve, both being emergent properties of the same elastic-recoil mechanism. Among the taxa examined, we find muscle-powered and fully fledged elastic systems with enormous performance differences, but no intermediate forms, suggesting that incipient elastic mechanisms do not persist in evolutionary time. A growing body of data from other elastic systems suggests that similar coevolution of traits may be found in other ectothermic animals with high performance, particularly those for which thermoregulation is challenging or ecologically costly.

Animal movement, mechanical tuning and coupled systems

1999 ◽  
Vol 202 (23) ◽  
pp. 3415-3421 ◽  
Author(s):  
T.L. Daniel ◽  
M.S. Tu
Keyword(s):  
Molecular Basis ◽  
Animal Studies ◽  
Neural Control ◽  
Animal Movement ◽  
Coupled Systems ◽  
Force Generation ◽  
Muscle Physiology ◽  
The Past ◽  
Animal Physiology ◽  
Mechanical Tuning

Over the past two decades, there has been a growing interest in developing predictive models of animal movement and force generation in fluids. In a departure from past studies that have asked how prescribed motions of a propulsor (wing or fin) generate lift and thrust during swimming and flying, we are increasingly interested in predicting the propulsor's movement as well as the forces generated by it. This interest, motivated by a need to understand the control and dynamics of locomotion and its applications to robotics and animal physiology, requires that we develop integrative models and analyses of swimming and flying that incorporate neural control and muscle physiology into more traditional biomechanical studies of locomotion in fluids. This approach extends from whole-animal studies to the molecular basis of force generation. In this paper, we explore mechanical tuning from the level of the whole animal to the proteins driving force generation in muscle.

scholarly journals An integrated multiscale, multicellular skin model

2019 ◽  
Author(s):  
Ryan Tasseff ◽  
Boris Aguilar ◽  
Simon Kahan ◽  
Seunghwa Kang ◽  
Charles C. Bascom ◽  
...  
Keyword(s):  
Differential Equations ◽  
Cell Biology ◽  
High Performance ◽  
Skin Barrier ◽  
Skin Barrier Function ◽  
Emergent Properties ◽  
Skin Model ◽  
Environmental Chemical ◽  
Software Models

ABSTRACTSkin is our primary barrier to the outside world, protecting us from physical, biological and chemical threats. Developing innovative products that preserve and improve skin barrier function requires a thorough understanding of the mechanisms underlying barrier response to topical applications. In many fields, computer simulations already facilitate understanding, thus accelerating innovation. Simulations of software models allow scientists to test hypothesized mechanisms by comparing predicted results to physical observations. They also enable virtual product optimization, without physical experiments, once mechanisms have been validated. The physical accessibility and abundant knowledge of skin structure makes it a prime candidate for computational modeling. In this article, we describe a computational multiscale multicellular skin model used to simulate growth and response of the epidermal barrier. The model integrates several modeling styles and mathematical frameworks including ordinary differential equations, partial differential equations, discrete agent-based modeling and discrete element methods. Specifically, to capture cell biology and physical transport, we combined four distinct sub-models from existing literature. We also implemented methods for elastic biomechanics. Our software implementation of the model is compatible with the high-performance computing simulation platform Biocellion. The integrated model recapitulates barrier formation, homeostasis and response to environmental, chemical and mechanical perturbation. This work exemplifies methodology for integrating models of vastly different styles. The methodology enables us to effectively build on existing knowledge and produce “whole-system” tissue models capable of displaying emergent properties. It also illustrates the inherent technical difficulties associated with the mounting complexity of describing biological systems at high fidelity. Among the challenges are validation of the science, the mathematical representations approximating the science and the software implementing these representations. Responsibility for a discrepancy observed between in silico and in vitro results may as easily lie at one of these three levels as at another, demanding that any sustainable modeling endeavor engage expertise from biology, mathematics and computing.

scholarly journals Locomotor kinematics and EMG activity during quadrupedal versus bipedal gait in the Japanese macaque

2019 ◽  
Vol 122 (1) ◽  
pp. 398-412 ◽  
Author(s):  
Yasuo Higurashi ◽  
Marc A. Maier ◽  
Katsumi Nakajima ◽  
Kazunori Morita ◽  
Soichiro Fujiki ◽  
...  
Keyword(s):  
Neural Control ◽  
Japanese Monkey ◽  
Japanese Macaque ◽  
Spatial Optimization ◽  
Joint Kinematics ◽  
Emg Activity ◽  
Emergent Properties ◽  
Bipedal Locomotion ◽  
Double Support ◽  
Bipedal Gait

Several qualitative features distinguish bipedal from quadrupedal locomotion in mammals. In this study we show quantitative differences between quadrupedal and bipedal gait in the Japanese monkey in terms of gait patterns, trunk/hindlimb kinematics, and electromyographic (EMG) activity, obtained from 3 macaques during treadmill walking. We predicted that as a consequence of an almost upright body axis, bipedal gait would show properties consistent with temporal and spatial optimization countering higher trunk/hindlimb loads and a less stable center of mass (CoM). A comparatively larger step width, an ~9% longer duty cycle, and ~20% increased relative duration of the double-support phase were all in line with such a strategy. Bipedal joint kinematics showed the strongest differences in proximal, and least in distal, hindlimb joint excursions compared with quadrupedal gait. Hindlimb joint coordination (cyclograms) revealed more periods of single-joint rotations during bipedal gait and predominance of proximal joints during single support. The CoM described a symmetrical, quasi-sinusoidal left/right path during bipedal gait, with an alternating shift toward the weight-supporting limb during stance. Trunk/hindlimb EMG activity was nonuniformally increased during bipedal gait, most prominently in proximal antigravity muscles during stance (up to 10-fold). Non-antigravity hindlimb EMG showed altered temporal profiles during liftoff or touchdown. Muscle coactivation was more, but muscle synergies less, frequent during bipedal gait. Together, these results show that behavioral and EMG properties of bipedal vs. quadrupedal gait are quantitatively distinct and suggest that the neural control of bipedal primate locomotion underwent specific adaptations to generate these particular behavioral features to counteract increased load and instability. NEW & NOTEWORTHY Bipedal locomotion imposes particular biomechanical constraints on motor control. In a within-species comparative study, we investigated joint kinematics and electromyographic characteristics of bipedal vs. quadrupedal treadmill locomotion in Japanese macaques. Because these features represent (to a large extent) emergent properties of the underlying neural control, they provide a comparative, behavioral, and neurophysiological framework for understanding the neural system dedicated to bipedal locomotion in this nonhuman primate, which constitutes a critical animal model for human bipedalism.

scholarly journals Is My Model Good Enough? Best Practices for Verification and Validation of Musculoskeletal Models and Simulations of Movement

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Jennifer L. Hicks ◽  
Thomas K. Uchida ◽  
Ajay Seth ◽  
Apoorva Rajagopal ◽  
Scott L. Delp
Keyword(s):  
Modeling And Simulation ◽  
Neural Control ◽  
Software Verification ◽  
Animal Movement ◽  
Human Mobility ◽  
Research Question ◽  
Contact Forces ◽  
Verification And Validation ◽  
Major Barrier ◽  
General Process

Computational modeling and simulation of neuromusculoskeletal (NMS) systems enables researchers and clinicians to study the complex dynamics underlying human and animal movement. NMS models use equations derived from physical laws and biology to help solve challenging real-world problems, from designing prosthetics that maximize running speed to developing exoskeletal devices that enable walking after a stroke. NMS modeling and simulation has proliferated in the biomechanics research community over the past 25 years, but the lack of verification and validation standards remains a major barrier to wider adoption and impact. The goal of this paper is to establish practical guidelines for verification and validation of NMS models and simulations that researchers, clinicians, reviewers, and others can adopt to evaluate the accuracy and credibility of modeling studies. In particular, we review a general process for verification and validation applied to NMS models and simulations, including careful formulation of a research question and methods, traditional verification and validation steps, and documentation and sharing of results for use and testing by other researchers. Modeling the NMS system and simulating its motion involves methods to represent neural control, musculoskeletal geometry, muscle–tendon dynamics, contact forces, and multibody dynamics. For each of these components, we review modeling choices and software verification guidelines; discuss variability, errors, uncertainty, and sensitivity relationships; and provide recommendations for verification and validation by comparing experimental data and testing robustness. We present a series of case studies to illustrate key principles. In closing, we discuss challenges the community must overcome to ensure that modeling and simulation are successfully used to solve the broad spectrum of problems that limit human mobility.

scholarly journals Optimize the Power Consumption and SNR of the 3D Photonic High-Radix Switch Architecture Based on Extra Channels and Redundant Rings

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Jie Jian ◽  
Mingche Lai ◽  
Liquan Xiao
Keyword(s):  
High Performance ◽  
Process Variation ◽  
Optical Switch ◽  
Signal To Noise Ratio ◽  
Thermal Sensitivity ◽  
Optical Network ◽  
Research Field ◽  
Switch Architecture ◽  
Static Power ◽  
High Radix

The demand from exascale computing has made the design of high-radix switch chips an attractive and challenging research field in EHPC (exascale high-performance computing). The static power, due to the thermal sensitivity and process variation of the microresonator rings, and the cross talk noise of the optical network become the main bottlenecks of the network’s scalability. This paper proposes the analyze model of the trimming power, process variation power, and signal-to-noise ratio (SNR) for the Graphein-based high-radix optical switch networks and uses the extra channels and the redundant rings to decrease the trimming power and the process variation power. The paper also explores the SNR under different configurations. The simulation result shows that when using 8 extra channels in the 64×64 crossbar optical network, the trimming power reduces almost 80% and the process variation power decreases 65% by adding 16 redundant rings in the 64×64 crossbar optical network. All of these schemes have little influence on the SNR. Meanwhile, the greater channel spacing has great advantages to decrease the static power and increase the SNR of the optical network.

Muscle Contractile Function and Neural Control after Repetitive Endurance Cycling

2010 ◽  
Vol 42 (1) ◽  
pp. 206-212 ◽  
Author(s):  
EMMA Z. ROSS ◽  
WARREN GREGSON ◽  
KAREN WILLIAMS ◽  
COLIN ROBERTSON ◽  
KEITH GEORGE
Keyword(s):  
Neural Control ◽  
Contractile Function ◽  
Endurance Cycling ◽  
Muscle Contractile

scholarly journals Emerging ideas and tools to study the emergent properties of the cortical neural circuits for voluntary motor control in non-human primates

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 749 ◽  
Author(s):  
John F. Kalaska
Keyword(s):  
Motor Control ◽  
Neural Control ◽  
Neural Circuits ◽  
Neuron Activity ◽  
Emergent Properties ◽  
Control Mechanisms ◽  
Single Neurons ◽  
Electrode Arrays ◽  
Voluntary Motor ◽  
Neurophysiological Studies

For years, neurophysiological studies of the cerebral cortical mechanisms of voluntary motor control were limited to single-electrode recordings of the activity of one or a few neurons at a time. This approach was supported by the widely accepted belief that single neurons were the fundamental computational units of the brain (the “neuron doctrine”). Experiments were guided by motor-control models that proposed that the motor system attempted to plan and control specific parameters of a desired action, such as the direction, speed or causal forces of a reaching movement in specific coordinate frameworks, and that assumed that the controlled parameters would be expressed in the task-related activity of single neurons. The advent of chronically implanted multi-electrode arrays about 20 years ago permitted the simultaneous recording of the activity of many neurons. This greatly enhanced the ability to study neural control mechanisms at the population level. It has also shifted the focus of the analysis of neural activity from quantifying single-neuron correlates with different movement parameters to probing the structure of multi-neuron activity patterns to identify the emergent computational properties of cortical neural circuits. In particular, recent advances in “dimension reduction” algorithms have attempted to identify specific covariance patterns in multi-neuron activity which are presumed to reflect the underlying computational processes by which neural circuits convert the intention to perform a particular movement into the required causal descending motor commands. These analyses have led to many new perspectives and insights on how cortical motor circuits covertly plan and prepare to initiate a movement without causing muscle contractions, transition from preparation to overt execution of the desired movement, generate muscle-centered motor output commands, and learn new motor skills. Progress is also being made to import optical-imaging and optogenetic toolboxes from rodents to non-human primates to overcome some technical limitations of multi-electrode recording technology.

scholarly journals High-Performance Piezoresistive MEMS Strain Sensor with Low Thermal Sensitivity

Sensors ◽  
2011 ◽  
Vol 11 (2) ◽  
pp. 1819-1846 ◽  
Author(s):  
Ahmed Mohammed ◽  
Walied Moussa ◽  
Edmond Lou
Keyword(s):  
High Performance ◽  
Thermal Sensitivity ◽  
Strain Sensor
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