scholarly journals The primacy of rhythm: how discrete actions merge into a stable rhythmic pattern

2019 ◽  
Vol 121 (2) ◽  
pp. 574-587 ◽  
Author(s):  
Zhaoran Zhang ◽  
Dagmar Sternad
Keyword(s):  
Building Blocks ◽  
Periodic Pattern ◽  
Voluntary Movements ◽  
Rhythmic Pattern ◽  
Rhythmic Movements ◽  
Discrete Movements ◽  
Floquet Multipliers ◽  
Physiological Processes ◽  
Rhythmic Behavior ◽  
Virtual Target

This study examined how humans spontaneously merge a sequence of discrete actions into a rhythmic pattern, even when periodicity is not required. Two experiments used a virtual throwing task, in which subjects performed a long sequence of discrete throwing movements, aiming to hit a virtual target. In experiment 1, subjects performed the task for 11 sessions. Although there was no instruction to perform rhythmically, the variability of the interthrow intervals decreased to a level comparable to that of synchronizing with a metronome; furthermore, dwell times shortened or even disappeared with practice. Floquet multipliers and decreasing variability of the arm trajectories estimated in state space indicated an increasing degree of dynamic stability. Subjects who achieved a higher level of periodicity and stability also displayed higher accuracy in the throwing task. To directly test whether rhythmicity affected performance, experiment 2 disrupted the evolving continuity and periodicity by enforcing a pause between successive throws. This discrete group performed significantly worse and with higher variability in their arm trajectories than the self-paced group. These findings are discussed in the context of previous neuroimaging results showing that rhythmic movements involve significantly fewer cortical and subcortical activations than discrete movements and therefore may pose a computationally more parsimonious solution. Such emerging stable rhythms in neuromotor subsystems may serve as building blocks or dynamic primitives for complex actions. The tendency for humans to spontaneously fall into a rhythm in voluntary movements is consistent with the ubiquity of rhythms at all levels of the physiological system. NEW & NOTEWORTHY When performing a series of throws to hit a target, humans spontaneously merged successive actions into a continuous approximately periodic pattern. The degree of rhythmicity and stability correlated with hitting accuracy. Enforcing irregular pauses between throws to disrupt the rhythm deteriorated performance. Stable rhythmic patterns may simplify control of movement and serve as dynamic primitives for more complex actions. This observation reveals that biological systems tend to exhibit rhythmic behavior consistent with a plethora of physiological processes.

Rhythmic Leaf Movements of Some Common Weeds

Weed Science ◽  
1979 ◽  
Vol 27 (4) ◽  
pp. 401-415 ◽  
Author(s):  
Robert N. Andersen ◽  
Willard L. Koukkari
Keyword(s):  
Chenopodium Album ◽  
Continuous Light ◽  
Datura Stramonium ◽  
Amaranthus Retroflexus ◽  
Rhythmic Pattern ◽  
Weed Species ◽  
Rhythmic Movements ◽  
Wild Mustard ◽  
Dark Regime ◽  
Leaf Movements

In growth chamber studies, we measured the movement of cotyledons and leaves or leaflets in seedlings of nine weed species to determine: the magnitude of movement, whether movements followed a rhythmic pattern, and if rhythmic movements were endogenously controlled. Seedlings were always entrained under a 15-h light:9-h dark regime. Measurements were made at 3-h intervals for 3 to 4 days under four light regimes: alternating 15-h light:9-h dark; continuous light; one 15-h light:9-h dark span, followed by continuous light; and a 15-h light:9-h dark regime, in which the dark span was advanced 9 h (phase shift) when measurements were begun. No clearly defined pattern of leaf movement was found in wild mustard [Brassica kaber(DC.) L. C. Wheeler var.pinnatifida(Stokes) L. C. Wheeler]. Daily rhythmic leaf movements that did not appear to be endogenously controlled were found in redroot pigweed (Amaranthus retroflexusL.) and black nightshade (Solanum nigrumL.). Circadian rhythmic leaf movements that appeared to be under endogenous control were found in jimson-weed (Datura stramoniumL.), common lambsquarters (Chenopodium albumL.), common cocklebur (Xanthium pensylvanicumWallr.), prickly sida (Sida spinosaL.), sicklepod (Cassia obtusifoliaL.), and coffee senna (Cassia occidentalisL.).

Building blocks

2018 ◽  
Author(s):  
Nathan F. Lepora
Keyword(s):  
Neural Circuits ◽  
Animal Movement ◽  
Building Blocks ◽  
Rhythmic Movements ◽  
Artificial System ◽  
The Senses ◽  
The Individual ◽  
Animal Skin ◽  
Taste And Smell

This chapter introduces the “building blocks” section of the Handbook of Living Machines which explores the individual sensory and motor components that when pieced together can comprise a complete biological or artificial system. The first six chapters cover the senses of vision, audition, touch, taste, and smell (considered together as chemosensing, proprioception, and electrosensing). The remaining chapters review aspects of the biomimetics of animal movement. First, that biological muscle has many performance benefits compared with conventional electric, second, how oscillations in neural circuits can drive rhythmic movements, and finally the capacity of animal skin, in species such as geckos, to adhere to surfaces and support behaviors such as climbing.

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 Amino Acids as Building Blocks for Carbonic Anhydrase Inhibitors

2018 ◽  
Author(s):  
Niccolò Chiaramonte ◽  
Maria Novella Romanelli ◽  
Elisabetta Teodori ◽  
Claudiu Supuran
Keyword(s):  
Organic Chemistry ◽  
Amino Acids ◽  
Carbonic Anhydrase ◽  
Chemical Properties ◽  
Building Blocks ◽  
Carbonic Anhydrases ◽  
Carbonic Anhydrase Inhibitors ◽  
Physiological Processes ◽  
Long Time ◽  
Reversible Hydration

Carbonic Anhydrases (CAs) are a superfamily of metalloenzymes widespread in all life kingdoms, classified into seven genetically different families (α-θ). These enzymes catalyse the reversible hydration of carbonic anhydride (CO2), generating bicarbonate (HCO3-) and protons (H+). Fifteen isoforms of human CA (hCA I-XV) have been isolated, their presence being fundamental for the regulation of many physiological processes. In addition, overexpression of some isoforms has been associated with the outbreak or the progression of several diseases. For this reason, for a long time CA inhibitors (CAIs) are used in the control of glaucoma and as diuretics. Furthermore, the search for new potential CAIs for other pharmacological applications is a very active field. Amino acids constitute the smallest fundamental monomers of protein and, due to their useful bivalent chemical properties, are widely used in organic chemistry. Both proteinogenic and non-proteinogenic amino acids have been extensively used to synthesize CAIs. This article provides an overview of the different strategies that have been used to design new CAIs containing amino acids, and how these bivalent molecules influence the properties of the inhibitors.

scholarly journals Fitts' law is not continuous in reciprocal aiming

2009 ◽  
Vol 277 (1685) ◽  
pp. 1179-1184 ◽  
Author(s):  
Raoul Huys ◽  
Laure Fernandez ◽  
Reinoud J. Bootsma ◽  
Viktor K. Jirsa
Keyword(s):  
Task Difficulty ◽  
Control Mechanism ◽  
Movement Time ◽  
Control Mechanisms ◽  
Rhythmic Movements ◽  
Discrete Movements ◽  
Explicit Formulation ◽  
Fitts Law ◽  
Aiming Movement ◽  
Human Nervous System

It takes longer to accomplish difficult tasks than easy ones. In the context of motor behaviour, Fitts' famous law states that the time needed to successfully execute an aiming movement increases linearly with task difficulty. While Fitts' explicit formulation has met criticism, the relation between task difficulty and movement time is invariantly portrayed as continuous. Here, we demonstrate that Fitts' law is discontinuous in reciprocal aiming owing to a transition in operative motor control mechanisms with increasing task difficulty. In particular, rhythmic movements are implemented in easy tasks and discrete movements in difficult ones. How movement time increases with task difficulty differs in both movement types. It appears, therefore, that the human nervous system abruptly engages a different control mechanism when task difficulty increases.

scholarly journals A Computational Model for Rhythmic and Discrete Movements in Uni- and Bimanual Coordination

2009 ◽  
Vol 21 (5) ◽  
pp. 1335-1370 ◽  
Author(s):  
Renaud Ronsse ◽  
Dagmar Sternad ◽  
Philippe Lefèvre
Keyword(s):  
Computational Model ◽  
Bimanual Coordination ◽  
Central Pattern Generators ◽  
Unified Model ◽  
Model Complexity ◽  
Rhythmic Movements ◽  
Discrete Movements ◽  
Oscillatory Systems ◽  
Small Set ◽  
Pattern Generators

Current research on discrete and rhythmic movements differs in both experimental procedures and theory, despite the ubiquitous overlap between discrete and rhythmic components in everyday behaviors. Models of rhythmic movements usually use oscillatory systems mimicking central pattern generators (CPGs). In contrast, models of discrete movements often employ optimization principles, thereby reflecting the higher-level cortical resources involved in the generation of such movements. This letter proposes a unified model for the generation of both rhythmic and discrete movements. We show that a physiologically motivated model of a CPG can not only generate simple rhythmic movements with only a small set of parameters, but can also produce discrete movements if the CPG is fed with an exponentially decaying phasic input. We further show that a particular coupling between two of these units can reproduce main findings on in-phase and antiphase stability. Finally, we propose an integrated model of combined rhythmic and discrete movements for the two hands. These movement classes are sequentially addressed in this letter with increasing model complexity. The model variations are discussed in relation to the degree of recruitment of the higher-level cortical resources, necessary for such movements.

Effects of Leg Pedaling on Early Latency Cutaneous Reflexes in Upper Limb Muscles

2010 ◽  
Vol 104 (1) ◽  
pp. 210-217 ◽  
Author(s):  
Syusaku Sasada ◽  
Toshiki Tazoe ◽  
Tsuyoshi Nakajima ◽  
E. Paul Zehr ◽  
Tomoyoshi Komiyama
Keyword(s):  
Upper Limb ◽  
Biceps Brachii ◽  
Lower Limbs ◽  
Functional Coupling ◽  
Isometric Contractions ◽  
Rhythmic Movements ◽  
Discrete Movements ◽  
Cutaneous Reflex ◽  
Limb Muscles ◽  
Control Research

The functional coupling of neural circuits between the upper and lower limbs involving rhythmic movements is of interest to both motor control research and rehabilitation science. This coupling can be detected by examining the effect of remote rhythmic limb movement on the modulation of reflex amplitude in stationary limbs. The present study investigated the extent to which rhythmic leg pedaling modulates the amplitude of an early latency (peak 30–70 ms) cutaneous reflex (ELCR) in the upper limb muscles. Thirteen neurologically intact volunteers performed leg pedaling (60 or 90 rpm) while simultaneously contracting their arm muscles isometrically. Control experiments included isolated isometric contractions and discrete movements of the leg. ELCRs were evoked by stimulation of the superficial radial nerve with a train of rectangular pulses (three pulses at 333 Hz, intensity 2.0- to 2.5-fold perceptual threshold). Reflex amplitudes were significantly increased in the flexor carpi radialis and posterior deltoid and significantly decreased in the biceps brachii muscles during leg pedaling compared with that during stationary isometric contraction of the lower leg muscles. This effect was also sensitive to cadence. No significant modulation was seen during the isometric contractions or discrete movements of the leg. Additionally, there was no phase-dependent modulation of the ELCR. These findings suggest that activation of the rhythm generating system of the legs affects the excitability of the early latency cutaneous reflex pathways in the upper limbs.

scholarly journals On the Multimodal Path to Language: The Relationship Between Rhythmic Movements and Deictic Gestures at the End of the First Year

2021 ◽  
Vol 12 ◽  
Author(s):  
Eva Murillo ◽  
Ignacio Montero ◽  
Marta Casla
Keyword(s):  
Rhythmic Movement ◽  
First Year ◽  
Rhythmic Movements ◽  
Transitional Phenomenon ◽  
Rhythmic Behavior ◽  
Instrumental Action ◽  
Communicative Gestures ◽  
First Year Of Life ◽  
The Relationship ◽  
Rhythmic Behaviors

The aim of this study is to analyze the relationship between rhythmic movements and deictic gestures at the end of the first year of life, and to focus on their unimodal or multimodal character. We hypothesize that multimodal rhythmic movement performed with an object in the hand can facilitate the transition to the first deictic gestures. Twenty-three children were observed at 9 and 12 months of age in a naturalistic play situation with their mother or father. Results showed that rhythmic movements with objects in the hand are a frequent behavior in children's repertoires. Rhythmic behaviors tend to decrease from 9 to 12 months, specifically when they are unimodal. Multimodal rhythmic behavior production at 9 months is positively related with proximal deictic gestures 3 months later. Multimodal rhythmic movements are not directly related to distal deictic gestures, but are indirectly related via proximal deictic gestures. These results highlight the relevance of multimodal behaviors in the transition to the use of early gestures, and can be considered as a transitional phenomenon between the instrumental action and early communicative gestures.

scholarly journals Moving slowly is hard for humans: limitations of dynamic primitives

2017 ◽  
Vol 118 (1) ◽  
pp. 69-83 ◽  
Author(s):  
Se-Woong Park ◽  
Hamal Marino ◽  
Steven K. Charles ◽  
Dagmar Sternad ◽  
Neville Hogan
Keyword(s):  
Motor Control ◽  
Alternative Hypothesis ◽  
Large Body ◽  
Cycle Duration ◽  
Rhythmic Movements ◽  
Discrete Movements ◽  
Human Motor Control ◽  
Neural Communication ◽  
Weak Evidence ◽  
Human Motor

Mounting evidence suggests that human motor control uses dynamic primitives, attractors of dynamic neuromechanical systems that require minimal central supervision. However, advantages for control may be offset by compromised versatility. Extending recent results showing that humans could not sustain discrete movements as duration decreased, this study tested whether smoothly rhythmic movements could be maintained as duration increased. Participants performed horizontal movements between two targets, paced by sounds with intervals that increased from 1 to 6 s by 200 ms per cycle and then decreased again. The instruction emphasized smooth rhythmic movements without interspersed dwell times. We hypothesized that 1) when oscillatory motions slow down, smoothness decreases; 2) slower oscillatory motions are executed as submovements or even discrete movements; and 3) the transition between smooth oscillations and submovements shows hysteresis. An alternative hypothesis was that 4) removing visual feedback restores smoothness, indicative of visually evoked corrections causing the irregularity. Results showed that humans could not perform slow and smooth oscillatory movements. Harmonicity decreased with longer intervals, and dwell times between cycles appeared and became prominent at slower speeds. Velocity profiles showed an increase with cycle duration of the number of overlapping submovements. There was weak evidence of hysteresis in the transition between these two types of movement. Eliminating vision had no effect, suggesting that intermittent visually evoked corrections did not underlie this phenomenon. These results show that it is hard for humans to execute smooth rhythmic motions very slowly. Instead, they “default” to another dynamic primitive and compose motion as a sequence of overlapping submovements. NEW & NOTEWORTHY Complementing a large body of prior work showing advantages of composing primitives to manage the complexity of motor control, this paper uncovers a limitation due to composition of behavior from dynamic primitives: while slower execution frequently makes a task easier, there is a limit and it is hard for humans to move very slowly. We suggest that this remarkable limitation is not due to inadequacies of muscle, nor to slow neural communication, but is a consequence of how the control of movement is organized.

Sign in / Sign up

Export Citation Format

Share Document