Complexity of modular neuromuscular control increases and variability decreases during human locomotor development

Sylos-Labini, Francesca; Scaleia, Valentina La; Cappellini, Germana; Dewolf, Arthur H.; Fabiano, Adele; Солопова, И. А.; Mondı̀, Vito; Ivanenko, Yuri P.; Lacquaniti, Francesco

doi:10.1038/s42003-022-04225-8

Cited by 17 publications

(19 citation statements)

References 73 publications

(177 reference statements)

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“…A core modular repertoire is already present in the new-born, and skilled locomotion and different gaits emerge through recombination and constructive adaptation of this prenatally developed core motor repertoire, in interaction with evolving biomechanical constraints and environmental conditions [82]. This recent evidence of a conservative adaptive architecture is exactly what we would expect to see if adaptation of early developing (i.e.…”

Section: What Happens Next? Post-buoyancy Adaptation and Sensorimotor...mentioning

confidence: 74%

Hanging in there: Uterine Buoyancy Defines Homeostatic Set-Points for Gravity Adaptation in Humans

Wilkinson¹,

Ciaunica²

2023

Preprint

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Gravity is a fundamental force of nature, to which all biological systems, including human bodies, must adapt to survive. Maintaining bodily and behavioural integrity in the vertical spatial dimension whilst under continuous perturbation from gravity is a universal task for all living systems. However, gravity adaptation in human embodiment in utero and beyond is often overlooked. This paper suggests that prenatal buoyancy (i.e. adaptation to fluid medium) provides foundational set-points for antigravity homeostatic self-regulatory processes in humans. The concepts of homeostasis and allostasis are central to understanding biological self-organisation and adaptivity to the external environment. Organisms must maintain essential variables within certain bounds or ‘set-points’ in order to self-maintain and survive, despite ambient variation and entropic pressures. We propose a novel characterisation of antigravity adaptation as a core homeostatic drive, analogous to body temperature regulation. This proposal is based on a reconceptualization of self-regulation in relation to gravity constraints as a problem of density/buoyancy, not just mass/weight as it is typically considered. Specifically, we suggest a hypothetical foundational set-point for gravity homeostasis in prenatal neutral buoyancy via suspension of the foetus in amniotic fluid. Our proposal provides a principled route to naturalise the strong links between antigravity adaptation and emotionally valenced perceptions as expressions of satisfying core bodily needs. By highlighting the role of prenatal buoyancy in scaffolding self-regulatory processes in development, this paper aims to pave the way towards more accurate picture of how key developmental stages of human embodiment unfold across the sensorimotor lifespan.

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Section: What Happens Next? Post-buoyancy Adaptation and Sensorimotor...mentioning

confidence: 74%

Hanging in there: Uterine Buoyancy Defines Homeostatic Set-Points for Gravity Adaptation in Humans

Wilkinson¹,

Ciaunica²

2023

Preprint

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“…A recently method proposed by Ballarini et al (2021) where the consistency and similarity of both activation patterns and weighting coefficients were determined may shed light on this. However, most methods of determining the number of synergies require setting some threshold which leaves this an open issue for future research ( Sylos-Labini et al, 2022 ); see Supplementary material 5 for an alternative to the reconstruction accuracy (RA) used here.…”

Section: Discussionmentioning

confidence: 99%

Development of running is not related to time since onset of independent walking, a longitudinal case study

Bach

Zandvoort

Cappellini

et al. 2023

Front. Hum. Neurosci.

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IntroductionChildren start to run after they master walking. How running develops, however, is largely unknown.MethodsWe assessed the maturity of running pattern in two very young, typically developing children in a longitudinal design spanning about three years. Leg and trunk 3D kinematics and electromyography collected in six recording sessions, with more than a hundred strides each, entered our analysis. We recorded walking during the first session (the session of the first independent steps of the two toddlers at the age of 11.9 and 10.6 months) and fast walking or running for the subsequent sessions. More than 100 kinematic and neuromuscular parameters were determined for each session and stride. The equivalent data of five young adults served to define mature running. After dimensionality reduction using principal component analysis, hierarchical cluster analysis based on the average pairwise correlation distance to the adult running cluster served as a measure for maturity of the running pattern.ResultsBoth children developed running. Yet, in one of them the running pattern did not reach maturity whereas in the other it did. As expected, mature running appeared in later sessions (>13 months after the onset of independent walking). Interestingly, mature running alternated with episodes of immature running within sessions. Our clustering approach separated them.DiscussionAn additional analysis of the accompanying muscle synergies revealed that the participant who did not reach mature running had more differences in muscle contraction when compared to adults than the other. One may speculate that this difference in muscle activity may have caused the difference in running pattern.

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“…Additional to the overall trial-to-trial similarity of each condition, we aimed to reveal, if differences in the variability just occur in some synergies. To classify similar synergy vectors among participants, we used k-means clustering (kmeans function in Octave – see supplementary material) similar to recent synergy studies [24, 26, 30, 48, 74]. We computed the k-means clustering solution for a range of two to twelve clusters and repeated the process 100 times.…”

Section: Methodsmentioning

confidence: 99%

“…To date, only few studies have examined the role of muscle synergies in movement learning. For instance, Sylos-Labini et al [24] compared walking trial-to-trial variability of temporal synergy activations across different age groups, ranging from neonates to adults. They observed a decrease in variability during locomotor development.…”

Section: Introductionmentioning

confidence: 99%

Trial-to-trial similarity and distinctness of muscle synergy activation coefficients increases during learning and with a higher level of movement proficiency

Kaufmann,

Koller,

Wallnöfer

et al. 2023

Preprint

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Muscle synergy analyses are used to increase our understanding of motor control. Spatially fixed synergy vectors coordinate multiple co-active muscles through activation commands, known as activation coefficients. To better understand motor learning, it is crucial to know how synergy recruitment varies during a learning task and different levels of movement proficiency. Within one session participants walked on a line, a beam, and learned to walk on a tightrope – tasks that represent different levels of proficiency. Muscle synergies were extracted over all conditions and the number of synergies was determined through the knee-point of the total variance accounted for (tVAF) curve. We found that the tVAF of one synergy decreased with task proficiency (line < beam < tightrope). Additionally, trial-to-trial similarity and distinctness of synergy activation coefficients increased with proficiency and after a learning process. We conclude that precise adjustment and refinement of synergy activation coefficients play a crucial role in motor learning.

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Complexity of modular neuromuscular control increases and variability decreases during human locomotor development

Cited by 17 publications

References 73 publications

Hanging in there: Uterine Buoyancy Defines Homeostatic Set-Points for Gravity Adaptation in Humans

Hanging in there: Uterine Buoyancy Defines Homeostatic Set-Points for Gravity Adaptation in Humans

Development of running is not related to time since onset of independent walking, a longitudinal case study

Trial-to-trial similarity and distinctness of muscle synergy activation coefficients increases during learning and with a higher level of movement proficiency

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