scholarly journals The speed–curvature power law in Drosophila larval locomotion

2016 ◽  
Vol 12 (10) ◽  
pp. 20160597 ◽  
Author(s):  
Myrka Zago ◽  
Francesco Lacquaniti ◽  
Alex Gomez-Marin
Keyword(s):  
Power Law ◽  
Scaling Laws ◽  
Central Pattern Generators ◽  
Dynamic Effects ◽  
Muscle Properties ◽  
Wide Range ◽  
Behavioural Tracking ◽  
The Law ◽  
Pattern Generators ◽  
Almost All

We report the discovery that the locomotor trajectories of Drosophila larvae follow the power-law relationship between speed and curvature previously found in the movements of human and non-human primates. Using high-resolution behavioural tracking in controlled but naturalistic sensory environments, we tested the law in maggots tracing different trajectory types, from reaching-like movements to scribbles. For most but not all flies, we found that the law holds robustly, with an exponent close to three-quarters rather than to the usual two-thirds found in almost all human situations, suggesting dynamic effects adding on purely kinematic constraints. There are different hypotheses for the origin of the law in primates, one invoking cortical computations, another viscoelastic muscle properties coupled with central pattern generators. Our findings are consistent with the latter view and demonstrate that the law is possible in animals with nervous systems orders of magnitude simpler than in primates. Scaling laws might exist because natural selection favours processes that remain behaviourally efficient across a wide range of neural and body architectures in distantly related species.

scholarly journals The velocity-curvature power law in Drosophila larval locomotion

2016 ◽  
Author(s):  
Myrka Zago ◽  
Francesco Lacquaniti ◽  
Alex Gomez-Marin
Keyword(s):  
Power Law ◽  
Scaling Laws ◽  
Scaling Law ◽  
Fruit Fly ◽  
Pattern Generation ◽  
Geometric Constraints ◽  
Muscle Properties ◽  
Wide Range ◽  
The Law ◽  
Almost All

AbstractWe report the discovery that the locomotor trajectories generated by crawling fruit fly larvae follow the same power law relationship between speed and curvature previously found in the human motor control of hand-drawing, walking, eye movements and speech. Using high resolution behavioral tracking of individual flies in different sensory environments, we tested the power law by making maggots trace different trajectory types in naturalistic conditions, from reaching-like movements to scribbles. In all these conditions, we found that the law holds, and also that the exponent of the larval scaling law approaches 3/4, rather than the usual 2/3 exponent found in almost all human situations. This is consistent with recent findings on humans drawing ellipses on water, where dynamic effects related to medium viscosity have been shown to increase the exponent that would emerge from purely kinematic-geometric constraints. To our knowledge, the speed-curvature power law has only been studied in human and non-human primates, our work then being the first demonstration of the speed-curvature scaling principle in other species. As there are still different competing hypotheses for the origin of such law in humans (one invoking complex cortical computations in primates; another postulating its emergence from the coupling of viscoelastic muscle properties with simple central pattern generation) our findings in the larva demonstrate that the law is possible in an animal with a nervous system orders of magnitude simpler than that of humans, thus supporting the latter view. Given that our discovery is in Drosophila (amenable to precise genetic manipulations, electron microscopy reconstruction of neural circuits, imaging in behaving animals, electrophysiology, and other techniques) this opens great potential for uncovering the mechanistic implementation of the velocity-curvature power law. Such scaling laws might exist because natural selection favors processes that remain behaviorally efficient across a wide range of contexts in distantly related species. Our work is an effort to search for shared principles of animal behavior across phyla.

A General Rhythmic Pattern Generation Architecture for Legged Locomotion

2011 ◽  
pp. 202-230
Author(s):  
Zhijun Yang ◽  
Felipe M.G. França
Keyword(s):  
Critical Role ◽  
Central Pattern Generators ◽  
Legged Locomotion ◽  
Building Blocks ◽  
Pattern Generation ◽  
Rhythmic Pattern ◽  
Motor Information ◽  
Pattern Generators ◽  
Life Phenomena ◽  
Almost All

As an engine of almost all life phenomena, the motor information generated by the central nervous system (CNS) plays a critical role in the activities of all animals. After a brief review of some recent research results on locomotor central pattern generators (CPG), which is a concrete branch of studies on the CNS generating rhythmic patterns, this chapter presents a novel, macroscopic and model-independent approach to the retrieval of different patterns of coupled neural oscillations observed in biological CPGs during the control of legged locomotion. Based on scheduling by multiple edge reversal (SMER), a simple and discrete distributed synchroniser, various types of oscillatory building blocks (OBB) can be reconfigured for the production of complicated rhythmic patterns and a methodology is provided for the construction of a target artificial CPG architecture behaving as a SMER-like asymmetric Hopfield neural networks.

scholarly journals Age- and speed-dependent modulation of gaits in DSCAM2J mutant mice

2018 ◽  
Vol 119 (2) ◽  
pp. 723-737 ◽  
Author(s):  
Louise Thiry ◽  
Maxime Lemieux ◽  
Frédéric Bretzner
Keyword(s):  
Neural Networks ◽  
Down Syndrome ◽  
Central Pattern Generators ◽  
Mutant Mice ◽  
Dependent Manner ◽  
Molecular Signaling ◽  
Behavioral Repertoire ◽  
Cell Adherence ◽  
Wide Range ◽  
Pattern Generators

Gaits depend on the interplay between distributed spinal neural networks, termed central pattern generators, generating rhythmic and coordinated movements, primary afferents, and descending supraspinal inputs. Recent studies demonstrated that the mouse displays a rich repertoire of gaits. Changes in gaits occur in mutant mice lacking particular neurons or molecular signaling pathways implicated in the normal establishment of these neural networks. Given the role of the Down syndrome cell adherence molecule (DSCAM) to the formation and maintenance of spinal interneuronal circuits and sensorimotor integration, we have investigated its functional contribution to gaits over a wide range of locomotor speeds using freely walking mice. We show in this study that the DSCAM2J mutation, while not precluding any gait, impairs the age- and speed-dependent modulation of gaits. It impairs the ability of mice to maintain their locomotion at high treadmill speeds. DSCAM2J mutation induces the dominance of lateral walk over trot and the emergence of aberrant gaits for mice, such as pace and diagonal walk. Gaits were also more labile in DSCAM2J mutant mice, i.e., less stable, less attractive, and less predictable than in their wild-type littermates. Our results suggest that the DSCAM mutation affects the behavioral repertoire of gaits in an age- and speed-dependent manner. NEW & NOTEWORTHY Gaits evolve throughout development, up to adulthood, and according to the genetic background. Using mutant mice lacking DSCAM (a cell adherence molecule associated with Down syndrome), we show that the DSCAM2J mutation alters the repertoire of gaits according to the mouse’s age and speed, and prevents fast gaits. Such an incapacity suggests a reorganization of spinal, propriospinal, and supraspinal neuronal circuits underlying locomotor control in DSCAM2J mutant mice.

scholarly journals Evaluating the energetics of entrainment in a human–machine coupled oscillator system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryan T. Schroeder ◽  
James L. Croft ◽  
John E. A. Bertram
Keyword(s):  
Central Pattern Generators ◽  
Metabolic Cost ◽  
The Body ◽  
Vertical Force ◽  
Wide Range ◽  
Metabolic Expenditure ◽  
Pattern Generators ◽  
Positive Work ◽  
Phase Relationships

AbstractDuring locomotion, humans sometimes entrain (i.e. synchronize) their steps to external oscillations: e.g. swaying bridges, tandem walking, bouncy harnesses, vibrating treadmills, exoskeletons. Previous studies have discussed the role of nonlinear oscillators (e.g. central pattern generators) in facilitating entrainment. However, the energetics of such interactions are unknown. Given substantial evidence that humans prioritize economy during locomotion, we tested whether reduced metabolic expenditure is associated with human entrainment to vertical force oscillations, where frequency and amplitude were prescribed via a custom mechatronics system during walking. Although metabolic cost was not significantly reduced during entrainment, individuals expended less energy when the oscillation forces did net positive work on the body and roughly selected phase relationships that maximize positive work. It is possible that individuals use mechanical cues to infer energy cost and inform effective gait strategies. If so, an accurate prediction may rely on the relative stability of interactions with the environment. Our results suggest that entrainment occurs over a wide range of oscillation parameters, though not as a direct priority for minimizing metabolic cost. Instead, entrainment may act to stabilize interactions with the environment, thus increasing predictability for the effective implementation of internal models that guide energy minimization.

scholarly journals The Role of Entrainment in Human Walking: Energy Minimization in Oscillating Environments

2020 ◽  
Author(s):  
Ryan Schroeder ◽  
James Croft ◽  
John Bertram
Keyword(s):  
Energy Minimization ◽  
Central Pattern Generators ◽  
Metabolic Cost ◽  
Vertical Force ◽  
Effective Implementation ◽  
Wide Range ◽  
Metabolic Expenditure ◽  
Pattern Generators ◽  
Phase Relationships

Abstract During locomotion, humans often entrain (i.e. synchronize) their steps to external oscillations: e.g. swaying bridges, tandem walking, bouncy harnesses, vibrating treadmills, exoskeletons. Previous studies have discussed the role of nonlinear oscillators (e.g. central pattern generators) in facilitating entrainment. However, the underlying benefits of entrainment are unknown. Given substantial evidence that humans prioritize economy during locomotion, we tested whether reduced metabolic expenditure accompanies human entrainment to vertical force oscillations, where frequency and amplitude were prescribed via a custom mechatronics system during walking. Although metabolic cost was not significantly reduced during entrainment, individuals who experienced negative work from oscillations had a higher cost than those who experienced positive work, and subjects generally selected phase relationships indicating the latter. It is possible that individuals use mechanical cues to infer energy cost and inform effective gait strategies. If so, an accurate prediction may rely on the relative stability of interactions with the environment. Our results suggest that entrainment is preferred over a wide range of oscillation parameters, though not as a direct priority for minimizing metabolic cost. Instead, entrainment may act to stabilize interactions with the environment, thus increasing predictability for the effective implementation of internal models that guide energy minimization.

scholarly journals Stellar coronal X-ray emission and surface magnetic flux

2020 ◽  
Vol 640 ◽  
pp. A119 ◽  
Author(s):  
J. Zhuleku ◽  
J. Warnecke ◽  
H. Peter
Keyword(s):  
Magnetic Flux ◽  
Analytical Model ◽  
Power Law ◽  
Scaling Laws ◽  
Alfven Wave ◽  
The Sun ◽  
X Ray ◽  
Wide Range ◽  
Wave Heating ◽  
Power Law Index

Context. Observations show that the coronal X-ray emission of the Sun and other stars depends on the surface magnetic field. Aims. Using power-law scaling relations between different physical parameters, we aim to build an analytical model to connect the observed X-ray emission to the surface magnetic flux. Methods. The basis for our model are the scaling laws of Rosner, Tucker & Vaiana (RTV) that connect the temperature and pressure of a coronal loop to its length and energy input. To estimate the energy flux into the upper atmosphere, we used scalings derived for different heating mechanisms, such as field-line braiding or Alfvén wave heating. We supplemented this with observed relations between active region size and magnetic flux and derived scalings of how X-ray emissivity depends on temperature. Results. Based on our analytical model, we find a power-law dependence of the X-ray emission on the magnetic flux, LX ∝ Φm, with a power-law index m being in the range from about one to two. This finding is consistent with a wide range of observations, from individual features on the Sun, such as bright points or active regions, to stars of different types and varying levels of activity. The power-law index m depends on the choice of the heating mechanism, and our results slightly favor the braiding and nanoflare scenarios over Alfvén wave heating. In addition, the choice of instrument will have an impact on the power-law index m because of the sensitivity of the observed wavelength region to the temperature of the coronal plasma. Conclusions. Overall, our simple analytical model based on the RTV scaling laws gives a good representation of the observed X-ray emission. Therefore we might be able to understand stellar coronal activity though a collection of basic building blocks, like loops, which we can study in spatially resolved detail on the Sun.

Peranan Hukum Dalam Pembangunan Ekonomi Negara Menurut Pandangan Ibnu Khaldun

Al-Risalah ◽  
2018 ◽  
Vol 11 (02) ◽  
pp. 75
Author(s):  
M Lohot Hasibuan
Keyword(s):  
Economic System ◽  
National Economy ◽  
External Factors ◽  
Economic Productivity ◽  
Law System ◽  
The Law ◽  
Almost All

 The law is no longer a record of behaviors which shape  the live of society; instead the law is expected to reveal the new  powers which expect the prosperity of the society. As the result,  almost all aspects of life are tied by law. The law should also realize  that there are external factors which effect the law and in the  application in reality. In that way, when designing the law policy,  the designer needs to consider some aspects such as psychology,  sociology,  and  geography.  Concerning  on  the  development  of  national economy, Ibnu Khaldun stated that law system should be  based on religion rule for the reason that the law will organize the  economic  system  well  to  be  balance  and  develop  the  economic  productivity 

Effect of Central Pattern Generators Depended Different Walking Strategies on Gait Ability of Patients after Stroke

2017 ◽  
Vol 27 (2) ◽  
pp. 40
Author(s):  
Hua WU ◽  
Zaihua RU ◽  
Congying XU ◽  
Xudong GU ◽  
Jianming FU
Keyword(s):  
Central Pattern Generators ◽  
Pattern Generators

First Detection of Tobacco Mosaic Virus in Tobacco Fields in Northern Lebanon

2020 ◽  
Vol 20 ◽  
Author(s):  
Rami Obeid ◽  
Elias Wehbe ◽  
Mohamad Rima ◽  
Mohammad Kabara ◽  
Romeo Al Bersaoui ◽  
...  
Keyword(s):  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Viral Genome ◽  
Virus Genome ◽  
Enzyme Linked Immunosorbent Assay ◽  
Virus Family ◽  
Crop Fields ◽  
Wide Range ◽  
Almost All ◽  
Das Elisa

Background: Tobacco mosaic virus (TMV) is the most known virus in the plant mosaic virus family and is able to infect a wide range of crops, in particularly tobacco, causing a production loss. Objectives: Herein, and for the first time in Lebanon, we investigated the presence of TMV infection in crops by analyzing 88 samples of tobacco, tomato, cucumber and pepper collected from different regions in North Lebanon. Methods: Double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), revealed a potential TMV infection of four tobacco samples out of 88 crops samples collected. However, no tomato, cucumber and pepper samples were infected. The TMV+ tobacco samples were then extensively analyzed by RT-PCR to detect viral RNA using different primers covering all the viral genome. Results and Discussion: PCR results confirmed those of DAS-ELISA showing TMV infection of four tobacco samples collected from three crop fields of North Lebanon. In only one of four TMV+ samples, we were able to amplify almost all the regions of viral genome, suggesting possible mutations in the virus genome or an infection with a new, not yet identified, TMV strain. Conclusion: Our study is the first in Lebanon revealing TMV infection in crop fields, and highlighting the danger that may affect the future of agriculture.

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