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Results for “rhythmic movement”

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At least 289 records · Page 16Linked to original sources
PubMed1985

Characteristics of rhythmic jaw movements of the rabbit.

The jaw-movement pattern of the rabbit during chewing foods of different consistency was analysed. The basic movement trajectory on the frontal plane showed a crescent loop, irrespective of the food type. Difference in food consistency exerted only minor effects on the maximum gape, extent of lateral excursion and the chewing rate. These parameters of jaw movement and also the duration of a single masticatory cycle (TCL) appeared to change with physical properties other than the hardness of food. On the other hand, the number of chewing cycles in a masticatory sequence increased with increasing the hardness of food. The TCL ranged between 250 and 300 ms (frequency: 3.3-4 Hz). When a single masticatory cycle was divided into three phases (opening, closing and power phases), the TCL depended more on the duration of the opening phase than that of other two phases.

Animal Feed↗
PubMed1988

A technique for electrically induced perturbation of rhythmic leg movement.

The paper describes electrical circuitry which replaces a mechanical brake, for perturbation of the contractile load of the legs during pedalling. The turning flywheel of an ergometer is connected to an alternator, with the electrical load provided by a power resistor connected across the output terminals. A 12-V battery provides the field current. Through variable resistors the field current is altered under microprocessor control, providing different steady-state loads when pedalling and also sudden transient changes of load. The point of change in load in the movement cycle can be accurately selected. The ergometer is instrumented for accurate measurement of pedal crank position, crank angular velocity and reaction force at the foot, to provide a physical description of the evoked steady states and transients, using microprocessor controlled sampling. The results show that the technique has application to the study of the range of reflex responses within a movement cycle and also to the more complex restoration of a movement pattern over a number of cycles. It is applicable to investigation of normal and diseased states.

Electronics↗
PubMed2004

Attentional load associated with performing and stabilizing a between-persons coordination of rhythmic limb movements.

This study addressed the issue of intentional stabilization of between-persons coordination patterns (in-phase/isodirectional and anti-phase/non-isodirectional) and the attentional cost incurred by the nervous system in maintaining and further stabilizing these coordination patterns. Five pairs of participants performed in-phase and anti-phase interpersonal coordination patterns in dual-task conditions (coordination+RT task). Results showed that: (1) isodirectional pattern (in-phase) was more stable than non-isodirectional pattern (anti-phase), (2) both iso- and non-isodirectional pattern were stabilized intentionally, (3) RT was lower for the isodirectional pattern (i.e., the most stable), and (4) attentional manipulation led to a trade-off between pattern stability and RT performance. These results suggest that performing between-persons coordination patterns incurs a central cost that depends on the coupling strength between the limbs. These findings are consistent with the previous studies in intrapersonal coordination.

Adult↗
PubMed1998

Nonlinear dynamic systems evaluation of rhythmic' eye movements (optokinetic nystagmus).

The last decade has seen a surge in the study of nonlinear dynamical behavior in physiologic systems. In this paper, some of the computational techniques most commonly used to investigate the nonlinear dynamics of these systems are described. Applications to eye movement analysis are included, including the validation of a mathematical model of optokinetic nystagmus (OKN) eye movements. OKN appears to have some nonlinear and deterministic component, along with significant randomness. Fast phase starting and ending points are somewhat predictable (deterministic), while so-called 'exceptional events' analysis shows that they also have a large random component. Surrogate data methods suggest that the population of slow and fast phases in OKN is more important than any specific relationship between adjacent slow and fast phases. Analysis of a statistical model for fast phase intervals indicates that the model data are slightly more random than the actual OKN.

Computational Biology↗
PubMed2002

A dynamic pattern analysis of coordination between breathing and rhythmic arm movements in humans.

We investigated the behavioral dynamics of human breathing-wrist movement coordination in a 1:1 frequency locking task. A pronation-supination wrist movement and a short trial duration were chosen to limit both mechanical and metabolic constraints on the respiratory system. Subjects voluntarily controlled their breathing rhythm to follow the metronome. We found that pronation-expiration and pronation-inspiration patterns coexisted as the (sole) stable fixed-point attractors of the coordination system. The pronation-expiration pattern was more stable than the pronation-inspiration pattern. Depending on the oscillation frequency, this differential stability gave rise to both absolute and relative coordination. These results show that simple behavioral laws of coordination encapsulate neural coupling dynamics evidenced from experimental research in human beings and animals. They challenge the classical view that such a coupling is not present for all imposed movement frequencies. Rather, relative coordination emerges as a result of the modification of coupling strength with frequency. These results can be accommodated by the asymmetric version of the HKB model of coordination dynamics. Thus, our data suggest that the principles and models of coordination dynamics may be taken as a reference to study the coupling of the motor and physiological subsystems involved in breathing-movement coordination.

Arm↗
PubMed1998

Neural control of rhythmic arm movements.

In this paper we present an approach to robot arm control based on exploiting the dynamical properties of a simple neural network oscillator circuit coupled to the joints of an arm. The entrainment and input/output properties of the oscillators are used to perform a variety of tasks with the same architecture, without any modeling of the arm or its environment. The approach is implemented on two real robot arms, and has been used to tune into the resonant frequency of pendulums, perform multi-joint coordinated motion by turning cranks, and exploit the dynamics of a 'Slinky' toy to coordinate the motion of two arms. By exploiting the coupling between the physical arm and the neural oscillator, a range of complex behaviors can be achieved with a very simple system.

Journal Article↗
PubMed2006

Degree of coordination between breathing and rhythmic arm movements during hand rim wheelchair propulsion.

This study aimed (i) to quantify the spontaneous coordination between breathing and hand rim wheelchair propulsion, (ii) to manipulate arm movement frequency and assess its effects on spontaneous coordination, and (iii) to investigate the hypothesis that entrainment of breathing improves economy of locomotion and leads to a lower rate of perceived exertion (RPE) compared with spontaneous breathing. Nine male, able-bodied participants completed four bouts of 6 min submaximal steady state exercise at 60 % of maximal propulsion velocity on a wheelchair ergometer, with spontaneous breathing and arm frequencies (Fspont), with 20 % higher and lower arm frequencies (F +20 and F -20, respectively) compared to Fspont accompanied with spontaneous breathing frequency, and by synchronising expiration phase with pushing time and inspiration phase with upper limb recovery time (C). Oxygen uptake and propulsion frequency were continuously recorded. The degree of coordination was expressed as a percentage of inspiration starting in the same phase of the wheelchair propulsion cycle (i.e. pushing and recovery times). No difference in degree of coordination was observed between Fspont, F -20 and F +20 conditions (49.2 +/- 12.1 %, 49.1 +/- 29.0 % and 48.2 +/- 29.4 %, respectively). Oxygen uptake increased significantly during C condition while RPE was significantly lower for C and F -20 (p < 0.05) compared to F +20 conditions. Contrary to what we expected, entrainment of breathing using a monofrequency ratio (C) induced a higher energy cost probably due to the mechanical properties of the wheelchair propulsion activity itself. In conclusion, this study showed that the same locomotor-respiratory coupling occurred during hand rim wheelchair propulsion regardless of the arm movement frequency, and that entrainment of breathing did not improve economy of locomotion.

Adult↗
PubMed1993

Cortical tremor. A common manifestation of cortical myoclonus.

Ten patients, three with postural tremor and seven with action myoclonus, had stereotyped involuntary rhythmic movements when attempting to execute a sustained isometric muscle contraction. The movements were characterized by rhythmic EMG bursts lasting less than 50 msec and appearing synchronously in agonist and antagonist muscles at a rate of 9 to 18 Hz. Backaveraging of the EEG activity related to the onset of the rhythmic EMG bursts identified a cortical potential preceding the EMG bursts in all patients. These symptoms and signs fit the description of "cortical tremor," a variant of cortical reflex myoclonus. Cortical tremor is common in patients with cortical myoclonus and may be a source of functional disability. In two patients in whom we studied the effects of graded levels of isometric force, force recruitment modulated the abnormal EMG bursting frequency, amplitude, and spatial distribution of the myoclonic jerks in the activated limb. Transcranial magnetic and electrical stimulation, but not peripheral nerve stimulation, influenced the abnormal EMG bursting pattern, implying a greater dependence of this rhythmic phenomenon on a central generator than on peripheral feedback loops.

Adolescent↗
PubMed2003

Horizontal rhythmical eye movements consistently diminish the arousal provoked by auditory stimuli.

OBJECTIVES: Theoretical models implicating the orienting reflex as an explanatory mechanism in the eye-movement desensitization and reprocessing (EMDR) treatment protocol are contrasted and tested empirically. We also test whether EMDR effects are due to a distraction effect. DESIGN: A repeated measure design is used in two experiments. The first experiment employed two independent variables, eye condition (moving vs. stationary) and tone (a pseudo-randomized series of low and high intensity tones). In Expt 2, eye condition was replaced by attentional demand conditions (low or high). In both cases, electrodermal responses served as the dependent variable. METHOD: Participants were recruited from the Psychology Department at Cardiff University. In Expt 1, participants were required to either pursue a moving stimulus following auditory challenge or engage in an eyes-stationary task. In Expt 2, the task following auditory challenge required participants to identify specific items from letter strings in low and high attentional demand conditions. RESULTS: Lower levels of electrodermal arousal were identified in tasks eliciting eye movements, compared to no eye movements. This effect was not due to the attentional requirements of the task. CONCLUSIONS: Eye movements following auditory challenge result in an effect of psychophysiological de-arousal. This supports the reassurance reflex model of EMDR proposed by MacCulloch and Feldman (1996).

Acoustic Stimulation↗
PubMed2002

Cortical activation during rhythmic hand movements performed under three types of control: an fMRI study.

Echoplanar fMRI was used to measure changes in cortical activation during the performance of a simple hand movement task under three types of voluntary control. Each of three imaging series alternated a task with rest: passive (in which the experimenter moved the hand), voluntary against low resistance, and voluntary against higher resistance. Contralateral activation was observed in the supplementary motor area (SMA), the primary motor cortex (M1), and the somatosensory cortex (S1) in all three tasks in each subject, whereas ipsilateral activation differed in each cortical region for each task. SMA had the widest prevalence of ipsilateral activation in all three tasks. In the M1, ipsilateral activation was observed in all but 1 subject in the two voluntary tasks but in only a few subjects in the S1 in any of the tasks. Quantitative changes in signal intensity and spatial extent of activation differentiated the voluntary tasks from the passive task and were most pronounced in the S1.

Adolescent↗