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Results for “rhythmic movement”

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PubMed2002

Interaction of discrete and rhythmic movements over a wide range of periods.

This study investigates a complex task in which rhythmic and discrete components have to be combined in single-joint elbow rotations. While previous studies of similar tasks already reported that the initiation of the discrete movement is constrained to a particular phase window of the ongoing rhythmic movement, interpretations have remained contradictory due to differences in paradigms, oscillation frequencies, and data analysis techniques. The present study aims to clarify these findings and further elucidate the bidirectional nature of the interaction between discrete and rhythmic components. Participants performed single-degree-of-freedom elbow oscillatory movements at five prescribed periods (400, 500, 600, 800, 1,000 ms). They rapidly switched the midpoint of oscillation to a second target after an auditory signal that occurred at a random phase of the oscillation, without stopping the oscillation. Results confirmed that the phase of the discrete movement initiation is highly constrained with respect to the oscillation period. Further, the duration, peak velocity, and the overshoot of the discrete movement varied systematically with the period of the rhythmic movement. Effects of the discrete-onto-rhythmic component were seen in a phase resetting of the oscillation and a systematic acceleration after the discrete movement, which also varied as a function of the oscillation period. These results are interpreted in terms of an inhibitory bidirectional coupling between discrete and rhythmic movement. The interaction between discrete and rhythmic movement elements is discussed in comparison to sequential and gating processes suggested previously.

Adult↗

PubMed1999

Bimanual coordination between isometric contractions and rhythmic movements: an asymmetric coupling.

Interactions between rhythmically moving limbs typically result in attraction to a limited number of coordination modes, which are distinguished in terms of their stability. In addition, the stability of coordination typically decreases with elevations in movement frequency. To gain more insight into the neurophysiological mechanisms underlying these stability characteristics, the effects of phasic voluntary muscle activation onto the movement pattern of the contralateral limb as well as onto the stability of interlimb coordination were examined. This was done in circumstances in which a minimal degree of movement-elicited afferent information was available to mediate the coupling influences. The task involved rhythmic application of isometric torque by one hand, while the other hand was moving rhythmically with unconstrained amplitude. The effects of two levels of applied torque, two coordination patterns (inphase and antiphase), and two movement frequencies were determined, both at the behavioural level (movement kinematics and kinetics) and the neuromuscular level (EMG). The isometric applications of torque clearly influenced the muscle-activation profile and movement pattern of the other limb, affecting both temporal variability and amplitude. Surprisingly, there were no differences between the two coordination patterns or between the tempo conditions. As such, the results did not conform to the Haken-Kelso-Bunz model for rhythmic movement coordination. These data suggest that the archetypal differences in stability of rhythmic bimanual coordination are contingent upon a correspondence between the limbs in terms of their respective tasks. This interpretation is elaborated in terms of the role of sensory feedback and the functional specificity of motor unit recruitment in rhythmic interlimb coordination.

Adult↗

PubMedDate not supplied

[Detection of isoenergetic discreteness in various rhythmic movements].

It has been found that phasic trajectories were composed of some few elliptical segments during rhythmic movements of human forearm at the elbow. The control program of the movement was shown to be realised as piece constant functions of two control parameters depending on boundary conditions in junctions of the elliptical segments. The control process at the interval between junctions is characterized by an energetic functional being invariant in respect to the trajectories of movements.

Elbow Joint↗

PubMed1991

Steady-state and perturbed rhythmical movements: a dynamical analysis.

This study examined rhythmic finger movements in the steady state and when momentarily perturbed in order to derive their qualitative dynamical properties. Movement frequency, amplitude, and peak velocity were stable under perturbation, signaling the presence of an attractor, and the topological dimensionality of that attractor was approximately equal to one. The strength of the attractor was constant with increasing movement frequency, and the Fourier spectra of the steady-state trials showed an alternating harmonic pattern. These results are consistent with a previously derived nonlinear oscillator model. However, the oscillation was phase advanced by perturbation overall, and a consistent phase-dependent, phase-shift pattern occurred, which is inconsistent with the model. The overall phase advance also shows that any central pattern generator responsible for generating the rhythm must be nontrivially modulated by the limb being controlled.

Adult↗

PubMedDate not supplied

[Reaction of the muscles to disturbance during single-joint rhythmic movement].

The muscle force action at the human elbow joint was studied during disturbed and non-disturbed horizontal rhythmic movement of forearm. It was shown that at the initial phase of unshocked perturbation++ the muscles efficiently resist the loading because its viscoelastic properties are quickly changed. Then the influence of the changes is almost vanished, apparently, with participation of nervous regulation.

Elbow Joint↗

PubMed1984

A qualitative model of the control of automated rhythmic movements: coupling between EEG and motor systems.

The aim of this study is to show a model of processing control of automated rhythmic movements. On the basis of different tapping tasks (real movements and ideomotor test situation) a scheme will be shown which describes the process control of different process levels with different feedback possibilities and with the influence of slow rhythms. Furthermore, a mathematical approach for the phenomena occurring during a tapping task in the EEG will be discussed. The model test and the scheme are the first attempts to describe the whole control system of automated rhythmic activity. In this first step the physiological substrate of the scheme elements was intentionally left out.

Adolescent↗

PubMed1976

[Reproduction of a given frequency of rhythmic movements in lesions of different motor formations].

By means of the tapping method the authors studied the capability of reproducting induced paces of rhythmical movements in 22 patients with the localization of the pathological process in subcortical nodes and in the brain stem. The induction of temporary programmes was accomplished by an electrophotostimulator, while the tapping registration--by an electromyo- and electroencephalographic method. It was demonstrated that in parkinsonic patients the most successful reproduction was accomplished in a pace of 6 hz. In cortical lesion there was a tendency to slow pace (1-2 hz), to a perseveration of made mistakes and a difficulty in transmitting from one pace to another. In stem lesions there was a disturbance in the reproduction of paces in all series of the experiment. The authors discuss the hypothesis of an existence of endogenous temporary programmes as an independent neurophysiological factor. It is being assumed that a study of the influence of external rhythmical signals on the internal (endogenous) time may have a decisive importance for special methods of rehabilitation of motor functions.

Brain Diseases↗

PubMed1996

A modified method of estimating phase resetting of rhythmical movement.

A computer-based method of estimating resetting index is presented which was successfully applied to a study of resetting of human voluntary rhythmical movement. Peaks were detected before and after the stimulus (magnetic cortical stimulation) from position records and the phase of stimulation and the phase change induced by the stimulus estimated. The phase change versus phase of stimulation relationship was rotated until the best linear fit was obtained: the gradient of this relationship is the resetting index. The calculation of resetting index was thus independent of the initial assignment of reference phase. A constant, the null phase, was derived from the best linear fit and indicates the phase to which the original waveform is being reset by the stimulus. Statistical tests of significance and linearity of the final relationship are also described.

Computers↗

PubMed2004

Visual feedback alters the variations in corticospinal excitability that arise from rhythmic movements of the opposite limb.

Augmented visual feedback can have a profound bearing on the stability of bimanual coordination. Indeed, this has been used to render tractable the study of patterns of coordination that cannot otherwise be produced in a stable fashion. In previous investigations (Carson et al. 1999), we have shown that rhythmic movements, brought about by the contraction of muscles on one side of the body, lead to phase-locked changes in the excitability of homologous motor pathways of the opposite limb. The present study was conducted to assess whether these changes are influenced by the presence of visual feedback of the moving limb. Eight participants performed rhythmic flexion-extension movements of the left wrist to the beat of a metronome (1.5 Hz). In 50% of trials, visual feedback of wrist displacement was provided in relation to a target amplitude, defined by the mean movement amplitude generated during the immediately preceding no feedback trial. Motor potentials (MEPs) were evoked in the quiescent muscles of the right limb by magnetic stimulation of the left motor cortex. Consistent with our previous observations, MEP amplitudes were modulated during the movement cycle of the opposite limb. The extent of this modulation was, however, smaller in the presence of visual feedback of the moving limb (FCR omega2=0.41; ECR omega2=0.29) than in trials in which there was no visual feedback (FCR omega2=0.51; ECR omega2=0.48). In addition, the relationship between the level of FCR activation and the excitability of the homologous corticospinal pathway of the opposite limb was sensitive to the vision condition; the degree of correlation between the two variables was larger when there was no visual feedback of the moving limb. The results of the present study support the view that increases in the stability of bimanual coordination brought about by augmented feedback may be mediated by changes in the crossed modulation of excitability in homologous motor pathways.

Adult↗

PubMed1984

Galloping tongue: post-traumatic, episodic, rhythmic movements.

Two patients experienced delayed onset of episodic, rhythmic, involuntary movements of the tongue after head and neck trauma. These three-per-second waves began as posterior midline focal tongue contractions, lasted about 10 seconds in each episode, persisted for 2 to 4 months, and were not accompanied by other body movements or by EEG abnormality.

Adult↗

PubMed2005

The excitator as a minimal model for the coordination dynamics of discrete and rhythmic movement generation.

The authors identify a class of excitable two-dimensional model systems, the excitators, that provide an entry point to the understanding of the mechanisms of discrete and rhythmic movement generation and a variety of related phenomena, such as false starts and the geometry of phase space trajectories. The starting point of their analysis is the topological properties of the phase flow. In particular, the phenomenon of false starts provides a characteristic structural condition for the phase flow, the separatrix, which partitions the phase space. Threshold phenomena, which are characteristic of excitable systems, as well as stable and unstable fixed points and periodic orbits, are discussed. Stable manifolds in the proximity of fixed points, resulting in an overshoot and a slow return phase after movement execution, are predicted in the analysis. To investigate coordination phenomena, the authors discuss the effects of two types of couplings, the sigmoidal coupling and a truncated version thereof, known as the Haken-Kelso-Bunz (HKB) coupling. They show analytically and numerically that the sigmoidal coupling leads to convergence phenomena in phase space, whereas the HKB coupling displays convergent as well as divergent behaviors. The authors suggest a specific representation of the excitator that allows the quantification of the predictions.

Humans↗

PubMed1986

Fluctuations and phase symmetry in coordinated rhythmic movements.

Pendular, clocking movements typify mammalian terrestrial locomotion. They can be investigated with a procedure in which people swing hand-held pendulums at the wrists, comfortably and rhythmically. Pendular, clocking behavior was examined for in-phase and out-of-phase coordinations. The periodic timing and powering of rhythmic movements in the comfort state follow from different laws (Kugler & Turvey, 1986). One law guides the assembling of the reference frame for "clocking." Another law guides the assembling of the muscular, escapement processes determining the cycle energy. Wing and Kristofferson's (1973) method for parsing periodic-timing variance into independent "clock" and "motor" sources was applied. Mean periodicity was unaffected by phase. "Clock" fluctuations, however, were larger out of phase than in phase. "Motor" fluctuations were indifferent to phase but reflected the departures of individual wrist-pendulum systems from their preferred periods. It appears that an intended phase relation is realized as a constraint on "clock" states. These states are more stable under the in-phase constraint than under the out-of-phase constraint.

Biophysical Phenomena↗

PubMed1996

One-Handed Juggling: A Dynamical Approach to a Rhythmic Movement Task.

The skill of rhythmically juggling a ball on a racket was investigated from the viewpoint of nonlinear dynamics. The difference equations that model the dynamical system were analyzed by means of local and nonlocal stability analyses. These analyses showed that the task dynamics offer an economical juggling pattern that is stable even for open-loop actuator motion. For this pattern, two types of predictions were extracted: (a) Stable periodic bouncing is sufficiently characterized by a negative acceleration of the racket at the moment of impact with the ball, and (b) a nonlinear scaling relation maps different juggling trajectories onto one topologically equivalent dynamical system. The relevance of these results for the human control of action was evaluated in an experiment in which subjects (N = 6) performed a comparable task of juggling a ball on a paddle. Task manipulations involved different juggling heights and gravity conditions of the ball. The following predictions were confirmed: (a) For stable rhythmic performance, the paddle's acceleration at impact is negative and fluctuations of the impact acceleration follow predictions from global stability analysis; and (b) for each subject, the realizations of juggling for the different experimental conditions are related by the scaling relation. These results permit one to conclude that humans reliably exploit the stable solutions inherent to the dynamics of the given task and do not overrule these dynamics by other control mechanisms. The dynamical scaling serves as an efficient principle for generating different movement realizations from only a few parameter changes and is discussed as a dynamical formalization of the principle of motor equivalence.

Journal Article↗

PubMed1992

Dynamical aspects of learning an interlimb rhythmic movement pattern.

Learning a bimanual rhythmic task is explored from the perspective that motor skill acquisition involves the successive reparameterization of a dynamical control structure in the direction of increasing stability, where the intentional process of reparameterization is itself dynamical. Subjects learned to oscillate pendulums held in the right and left hands such that the right hand frequency was twice that of the left (2:1 frequency lock). Over 12 learning sessions of 20 trials each, we interpreted the decreasing fluctuations in the frequency locking to be an index of the increasing concavity of the underlying potential, a measure of stability; the time required to achieve the 2: 1 pattern was interpreted as indexing the relaxation time of an intentional dynamic. Power spectral analyses of the phase velocity ratio exhibited two strategies for acquiring the interlimb movement pattern: (a) adding spectral peaks at integer multiples of the left hand frequency or (b) distributing power across many frequencies in a l/f-like manner. Results are discussed in terms of the promise of a dynamical approach to learning coordinated movements.

Journal Article↗

PubMed2005

Bimanual adaptation: internal representations of bimanual rhythmic movements.

From tying your shoes and clipping your tie to the claps at the end of a fine seminar, bimanual coordination plays a major role in our daily activities. An important phenomenon in bimanual coordination is the predisposition toward mirror symmetry in the performance of bimanual rhythmic movements. Although learning and adaptation in bimanual coordination are phenomena that have been observed, they have not been studied in the context of adaptive control and internal representations-approaches that were successfully employed in the arena of reaching movements and adaptation to force perturbations. In this paper we examine the dynamics of the learning mechanisms involved when subjects are trained to perform a bimanual non-harmonic polyrhythm in a bimanual index finger tapping task. Subjects are trained in this task implicitly, using altered visual feedback, while their performance is continuously monitored throughout the experiment. Our experimental results indicate the existence of significant (p<<0.01) learning curves (i.e., error plots with significantly negative slopes) during training and aftereffects with a washout period after the visual feedback ceases to be altered. These results confirm the formation of internal representations in bimanual motor control. We present a simple, physiologically plausible, neural model that combines feedback and adaptation in the control process and which is able to reproduce key phenomena of bimanual coordination and adaptation.

Adaptation, Physiological↗

PubMed1989

'Clock' and 'motor' components in absolute coordination of rhythmic movements.

Human subjects swung, through motions at the two wrists, hand-held pendulums of variable mass and length. Within a pair, the two pendulums could be of the same or different magnitude. The subjects were required to produce a coordinated state in which the two rhythmic units oscillated at a single common period. Fifty-four conditions of absolute coordination, that is, 54 different pairs of wrist-pendulum systems, were investigated for each of three subjects in the course of six sessions. Each condition of absolute coordination was conducted in the out of phase mode and at the single most comfortable period. The period variances of the right and left systems in the 162 instances of absolute coordination were analysed according to a method that assumes that a timekeeper function and a motor implementation function contribute independently to the variance in the periodic timing of a rhythmic movement. The major findings were that in absolute coordination: (a) a system's 'motor' variance, but not its 'clock' variance, depended on the deviation of the period of absolute coordination tau from the system's characteristic period; (b) right and left 'clock' variances were related and (c) neither the 'motor' variances nor the 'clock' variances were affected by deviations in the mean phase relation from 180 degrees. The results were discussed in terms of their implications for interpreting von Holst's notions of maintenance tendency and magnetic effect and, more generally, the neural and dynamical basis of absolute coordination.

Adult↗

PubMedDate not supplied

[Changes in the correlation of electroencephalograms connected with rhythmic movements].

Estimation of the correlation (C) between EEG processes is usually based on time averaging. Event-related changes in C around the mean level can be extracted with the help of ensemble averaging (synchronous accumulation). Fast and small non-stationary oscillations of C can be reliably distinguished in such a way. Curves of sign correlation averaged for 64 cycles were measured during rhythmic movements. It has been shown that the mean values of the curves coincide with the known ones. A high value of C for symmetric EEG recording and C dependence on the distance between the electrodes, etc. were found. Additional data were obtained on the relationship between changes in C and movement phases (an increase in C at the onset and the end of movement cycles multiphasic form of the C curves, etc.) and on the relation between the phases of various curves of C.

Electroencephalography↗

PubMed1988

Characteristic difficulty in rhythmic movement with aging and its relation to Parkinson's disease.

A total of 137 healthy participants aged from 20 to 79 years, including 59 over 60 years, were examined using a finger-tapping test. The test requested the participant to respond synchronously with the right middle finger to a periodic sound train with frequencies of 1, 2, 3, 4, and 5 Hz (cycles/sec). Difficulty keeping the rhythmic movement at a given rate was found to be a characteristic of aging. For the participants over 30 years, the mean rate of tapping deviated towards a faster rate for the stimulus frequency at 4 or 5 Hz (hastened tap, HT). The percentage of the participants who exhibited HT increased with decade of age; 0(20s), 11(30s), 13(40s), 17(50s), 30(60s) and 29(70s). HT in aging appears similar to hastened tapping which is typically observed in patients with Parkinson's disease and may be related to extrapyramidal dysfunction. Hastened tapping in the elderly supports the hypothesis that Parkinson's disease is a model for premature aging, suggesting that HT in aging represents an extrapyramidal motor dysfunction due to the neuroanatomical and neurochemical changes in the nigro-striatal system of the aging brain.

Adult↗