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1.
Musicians activate their muscles in different patterns, depending on their posture, the instrument being played, and their experience level. Bipolar surface electrodes have been used in the past to monitor such activity, but this method is highly sensitive to the location of the electrode pair. In this work, the spatial distribution of surface EMG (sEMG) of the right trapezius and right and left erector spinae muscles were studied in 16 violin players and 11 cello players. Musicians played their instrument one string at a time in sitting position with/without backrest support. A 64 sEMG electrode (16 × 4) grid, 10 mm inter-electrode distance (IED), was placed over the middle and lower trapezius (MT and LT) of the bowing arm. Two 16 × 2 electrode grids (IED = 10 mm) were placed on the left and right erector spinae muscles. Subjects played each of the four strings of the instrument either in large (1 bow/s) or detaché tip/tail (8 bows/s) bowing in two sessions (two days). In each of two days, measurements were repeated after half an hour of exercise to see the effect of exercise on the muscle activity and signal stability. A “muscle activity index” (MAI) was defined as the spatial average of the segmented active region of the RMS map. Spatial maps were automatically segmented using the watershed algorithm and thresholding. Results showed that, for violin players, sliding the bow upward from the tip toward the tail results in a higher MAI for the trapezius muscle than a downward bow. On the contrary, in cello players, higher MAI is produced in the tail to tip movement. For both instruments, an increasing MAI in the trapezius was observed as the string position became increasingly lateral, from string 1 (most medial) toward string 4 (most lateral). Half an hour of performance did not cause significant differences between the signal quality and the MAI values measured before and after the exercise. The MAI of the left and right erector spinae was smaller in the case of backrest support, especially for violin players. Back muscles of violin and cello players were activated asymmetrically, specifically in fast movements (detaché tip/tail). These findings demonstrate the sensitivity and stability of the technique and justify more extensive investigation following this proof of concept.  相似文献   

2.
The aim of this paper was to examine finger and bow string movements during archery by investigating a top Austrian athlete (FITA score = 1233) under laboratory conditions. Maximum lateral bow string deflection and angular displacements for index, third, and ring fingers between the full draw position and the end of the release were quantified using a motion tracking system. Stepwise multiple regression analyses were used to determine whether bow string deflection and finger movements are predictive for scoring. Joint ranges of motion during the shot itself were large in the proximal and distal interphalangeal joints, and much smaller in the metacarpophalangeal joints. Contrary to our expectations, greater deflection leads to higher scores (R2 = .18, p < .001) and the distal interphalangeal joint of the third finger weakly predicts the deflection (R2 = .11, p < .014). More variability in the joint angles of the third finger was found in bad shots than in good shots. Findings in this study let presume that maximum lateral bow string deflection does not adversely affect the archer's performance.  相似文献   

3.
 Various stability features of bimanual rhythmic coordination, including phase transitions, have been modeled successfully by means of a one-dimensional equation of motion for relative phase obeying a gradient dynamics, the Haken-Kelso-Bunz model. The present study aimed at assessing pattern stability for stationary performance and estimating the model parameters (a, b, and Q) for the stochastic extension of this model. Estimates of a and b allowed for reconstruction of the potential defining the gradient dynamics. Two coordination patterns between the forearms (in-phase, anti-phase) were performed at seven different frequencies. Model parameters were estimated on the basis of an exponential decay parameter describing the relaxation behavior of continuous relative phase following a mechanical perturbation. Variability of relative phase and relaxation time provided measures of pattern stability. Although the predicted inverse relation between pattern stability and movement frequency was observed for the lower tempo conditions, it was absent for the higher tempos, reflecting the influence of task constraints. No statistically significant differences in stability were observed between the two coordination modes, indicating the influence of intention. The reconstructed potential reflected the observed stability features, underscoring the adequacy of the parameter estimations. The relaxation process could not be captured adequately by means of a simple exponential decay function but required an additional oscillatory term. In accordance with previous assumptions, noise strength Q did not vary as a function of movement frequency. However, systematic differences in Q were observed between the two coordination modes. The advantages and (potential) pitfalls of using stationary performance of single patterns to examine the stability features of a bistable potential were discussed. Received: 12 July 1999 / Accepted in revised form: 14 April 2000  相似文献   

4.
The physical mechanics of music making is important both in the prevention of injuries and in guiding how music is performed and taught. Electromyography has potential as a resource in understanding the loads involved in instrumental playing; however, only a small number of projects have been undertaken, and little is understood on the muscle activity used during bowing on string instruments. This study aimed to measure the muscle activity at the bowing shoulder of a cellist during cello playing and to establish if fine-wire EMG is useful in understanding muscle recruitment in string players without interfering with normal playing ability. This project used a combination of fine-wire and surface EMG to evaluate the muscular load placed on the right shoulder of a professional cellist whilst playing a set of various bowing exercises. The results indicated that different bowing techniques produced statistically different muscle activity levels, with the supraspinatus muscle in particular maintaining higher mean contraction (20% MVC) during all bowing patterns tested. Fine-wire EMG was useful in measuring shoulder muscle load and did not interfere with normal playing technique of the subject. Overall, the study presents a working protocol from which future studies may be able conduct further research.  相似文献   

5.
Ryu YU  Buchanan JJ 《PloS one》2012,7(6):e38537
Visuomotor tracking tasks have been used to elucidate the underlying mechanisms that allow for the coordination of a movement to an environmental event. The main purpose of the present study was to examine the relationship between accuracy and stability of tracking performance and the amount of corrective movements that emerge for various coordination patterns in a unimanual visuomotor tracking task. Participants (N = 6) produced rhythmic elbow flexion-extension motions and were required to track an external sinusoidal signal at five different relative phases, 0°, 45°, 90°, 135°, and 180°. Differential accuracy and stability were found among the five tracking patterns with the 0° relative phase pattern being the most accurate and stable pattern. Corrective movements were correlated with changes in accuracy only for the 0° relative phase pattern, with more corrections emerging for less accurate performance. The amount of corrective movements decreased as the stability of tracking performance increased for the 0°, 45°, and 135° patterns. For the 90° and 180° tracking patterns, the amount of corrective movements was not correlated with pattern accuracy or pattern stability. The results demonstrate that corrective behaviors are an important motor process in maintaining the stability of stable perception-action coordination patterns, while offering little benefit for unstable perception-action patterns.  相似文献   

6.
The dissolved oxygen (DO) is an important variable in aerobic fermentations and affects the cell growth and product formation. Dissolved oxygen control is difficult in batch fermentations because of the time-varying conditions, time delays, and the probe dynamics. Modeling of the various patterns of biological activity in fermentations and their impact on the DO process dynamics is essential to both achieve a satisfactory control and to track the aforementioned patterns. An adaptive pole placement algorithm with time-delay compensation was used for controlling the DO, coupled with system identification using recursively estimated autoregressive models with exogeneous inputs (ARX). The flow rate of O2 in a constant flow rate gas inlet mixture is used as the manipulated variable. Supervision and coordination techniques are applied to improve the control performance. The control performance is affected by the accuracy of the model prediction and the selected time delay. The effect of DO level on the productivity of beta-lactamase using Bacillus subtilis under oxygen-limited conditions is investigated. Beta-lactamase stability is improved under prolonged growth conditions with low DO levels.  相似文献   

7.
String-pulling and patterned-string tasks are often used to analyse perceptual and cognitive abilities in animals. In addition, the paradigm can be used to test the interrelation between visual-spatial and motor performance. Two Australian parrot species, the galah (Eolophus roseicapilla) and the cockatiel (Nymphicus hollandicus), forage on the ground, but only the galah uses its feet to manipulate food. I used a set of string pulling and patterned-string tasks to test whether usage of the feet during foraging is a prerequisite for solving the vertical string pulling problem. Indeed, the two species used techniques that clearly differed in the extent of beak-foot coordination but did not differ in terms of their success in solving the string pulling task. However, when the visual-spatial skills of the subjects were tested, the galahs outperformed the cockatiels. This supports the hypothesis that the fine motor skills needed for advanced beak-foot coordination may be interrelated with certain visual-spatial abilities needed for solving patterned-string tasks. This pattern was also found within each of the two species on the individual level: higher motor abilities positively correlated with performance in patterned-string tasks. This is the first evidence of an interrelation between visual-spatial and motor abilities in non-mammalian animals.  相似文献   

8.
This study investigated the coordination and control strategies that the elderly adopt during a redundant finger force coordination task and how the amount of visual information regulates the coordination patterns. Three age groups (20-24, 65-69, and 75-79 yr) performed a bimanual asymmetric force task. Task asymmetry was manipulated via imposing different coefficients on the finger forces such that the weighted sum of the two index finger forces equaled the total force. The amount of visual information was manipulated by changing the visual information gain of the total force output. Two hypotheses were tested: the reduced adaptability hypothesis predicts that the elderly show less degree of force asymmetry between hands compared with young adults in the asymmetric coefficient conditions, whereas the compensatory hypothesis predicts that the elderly exhibit more asymmetric force coordination patterns with asymmetric coefficients. Under the compensatory hypothesis, two contrasting directions of force sharing strategies (i.e., more efficient coordination strategy and minimum variance strategy) are expected. A deteriorated task performance (high performance error and force variability) was found in the two elderly groups, but enhanced visual information improved the task performance in all age groups. With low visual information gain, the elderly showed reduced adaptability (i.e., less asymmetric forces between hands) to the unequal weighting coefficients, which supported the reduced adaptability hypothesis; however, the elderly revealed the same degree of adaptation as the young group under high visual gain. The findings are consistent with the notion that the age-related reorganization of force coordination and control patterns is mediated by visual information and, more generally, the interactive influence of multiple categories of constraints.  相似文献   

9.
No evidence of expertise-related changes in muscle synergies during rowing   总被引:1,自引:0,他引:1  
The purpose of the present study was to determine whether expertise in rowing is driven by a specific structure in muscular coordination. We compared seven experienced rowers and eight untrained (i.e., inexperienced) subjects during rowing on an ergometer. Both surface electromyography activity and mechanical patterns (forces exerted at the handle and the foot-stretcher) were recorded during a high intensity rowing exercise. A non-negative matrix factorization was applied to 23 electromyographic patterns to differentiate muscle synergies. Results showed that expertise was not associated with different dimensionality in the electromyographic data and that three muscle synergies were sufficient to explain the majority of the variance accounted for (i.e., >90% of the total variance) in the two populations. The synergies extracted were similar in the two populations, with identical functional roles. While the temporal organization of the propulsive synergies was very similar, slight differences were found in the composition of the muscle synergies (muscle synergy vectors) between the two populations. The results suggests that rowing expertise would not require the development of novel muscle synergies but would imply intrinsic synergies already used in different behaviors. Performance in rowing is more probably linked to adjustments in the mechanical output of the muscle synergies rather than to differences in the shape and timing of their activations.  相似文献   

10.
Duan X  Liao W  Liang D  Qiu L  Gao Q  Liu C  Gong Q  Chen H 《PloS one》2012,7(3):e32532
Cognitive performance relies on the coordination of large-scale networks of brain regions that are not only temporally correlated during different tasks, but also networks that show highly correlated spontaneous activity during a task-free state. Both task-related and task-free network activity has been associated with individual differences in cognitive performance. Therefore, we aimed to examine the influence of cognitive expertise on four networks associated with cognitive task performance: the default mode network (DMN) and three other cognitive networks (central-executive network, dorsal attention network, and salience network). During fMRI scanning, fifteen grandmaster and master level Chinese chess players (GM/M) and fifteen novice players carried out a Chinese chess task and a task-free resting state. Modulations of network activity during task were assessed, as well as resting-state functional connectivity of those networks. Relative to novices, GM/Ms showed a broader task-induced deactivation of DMN in the chess problem-solving task, and intrinsic functional connectivity of DMN was increased with a connectivity pattern associated with the caudate nucleus in GM/Ms. The three other cognitive networks did not exhibit any difference in task-evoked activation or intrinsic functional connectivity between the two groups. These findings demonstrate the effect of long-term learning and practice in cognitive expertise on large-scale brain networks, suggesting the important role of DMN deactivation in expert performance and enhanced functional integration of spontaneous activity within widely distributed DMN-caudate circuitry, which might better support high-level cognitive control of behavior.  相似文献   

11.
For more than 20 years, coordination dynamics have provided research on human movement science with new views about the nonlinear relationships between behavioral and neural dynamics. A number of studies across various experimental settings including bimanual, postural or interpersonal coordination, and also coordination between movements of a limb and an external event in the environment revealed the self-organized nature of human coordination. Here we review an extensive body of literature - in the human movement science and the neuroscience fields - that has investigated the coordination dynamics of brain and behavior when individuals are involved in two rhythmic coordination patterns: synchronization (on-the-beat movements) and syncopation (in-between beats movements). When the frequency of movement approaches 2 Hz, the syncopation mode is destabilized and synchronization is spontaneously adopted. The abrupt change between the two patterns illustrates a phenomenon known as non-equilibrium phase transition. Phase transitions offer a novel entry point into the investigation of pattern formation (and dissolution) at both the behavioral and the cerebral levels as they illustrate the loss of stability of the system. Brain imaging methods (MEG, EEG and fMRI) were used to reveal the neural signatures of (in)stability underlying the differences between behavioral coordination patterns, and pointed at the role of self-organization and metastability principles in brain functioning. Relationships between behavioral and brain dynamics can therefore be investigated within a unified empirical and theoretical framework.  相似文献   

12.
Previous studies showed that kea are able to cooperate in experiments based on the loose-string paradigm, but success rates were low, except when tested in stable dyads. We trained kea with low success rates to attend to the handling of the string by a human partner. This vastly improved subsequent coordination during cooperation with kea partners. Furthermore, we tested the kea dyads with a delayed entry set-up (delays of 2, 4 or 6 s) and with two different lengths of string. Increasing length of delay and reducing string length had negative effects on the success rate. This suggests that a complete understanding of the actions was not present as the kea were not able to fully overcome factors that inhibit coordination. Lastly, we tested the three subjects showing the greatest ability to wait for the partner in a partner-choice paradigm: one subject in the central position could pull a loose string with one partner after another in the order it preferred. As a result, the second subjects had much longer waiting times than previously experienced. We could show that the central kea learned to visit both set-ups and that the second partner was able to wait for the partner to arrive before attempting to pull on the string, averaging twice as long as in the standard delay. Taken together, the results from this study highlight that cooperation in the loose-string paradigm is largely dependent on coordination of the subjects. While attention to the partner's actions greatly improved performance, the greater waiting times achieved in the final set-up also suggest that utilizing more ecologically relevant (subject is busy VS subject is held back) delays could further improve the performance of non-human subjects in the delayed loose-string paradigm.  相似文献   

13.
Complex study of adaptation and allozyme belonging of alcoholdehydrogenase (ADH) in cn and vg mutants has been carried out in the initial pure lines, in their panmixia populations and in condition of substitution of the mutant genotype by saturating crossings. It was shown that the high level of adaptation of cn mutants and the low level of adaptation of vg mutants was combined with the presence of different ADH allozymes. During the saturating crossings the reliable coadaptation of the genes cn and Adh(S) as well as vg and Adh(F) was detected that confirmes the postulated earlier conception of gene adaptation complexes.  相似文献   

14.
The full speciation of the vanadium(V) complexation systems with two aminohydroxamic acids, aspartic-β- and glutamic-γ-hydroxamic acid, has been determined using potentiometric and spectroscopic techniques. Formation constants were calculated in a systematic study at different ligand to metal molar ratios and the coordination types are proposed. An almost constant value of the 51V NMR signal in neutral medium can be attributed to two (1:1 and 1:2 metal to ligand ratios) similar structures, both of which can be either protonated or deprotonated. The two ligands have a carboxylic group in the structure and show comparable biological activities. In this work analogous complexation behavior at physiological conditions was found despite the presence of two or three methylenic groups between the amino and hydroxamate groups. The carboxylic groups are quite distant from the hydroxamic groups and are not involved directly in the coordination process. Therefore the coordination structures are related to that found in the vanadium(V)-β-alaninehydroxamic acid in which there is not a carboxylic group.  相似文献   

15.
The preferential use of one hand over the other is considered the primary behavioral expression of structural and functional asymmetry in cerebral structures, which is a decisive factor in human evolution. We present the first analysis of manual laterality in a form of object play—stone handling (SH) behavior—in a free-ranging group of Japanese macaques. Defined as a stone-directed manipulative activity, and comprised of multiple one-handed SH patterns (e.g., grabbing a stone in one hand and cradling it against its chest), as well as coordinated two-handed SH patterns with manual role differentiation (e.g., holding a stone with one hand and rubbing it with the other), SH behavior is a good candidate for the study of hand lateralization. We systematically followed the methodological framework developed by McGrew and Marchant (1997) to measure and analyze the presence, strength, and direction of manual preference in the performance of SH behavior and in various SH patterns, both at the individual and group level. Some individuals showed a significant manual lateral bias on a single SH pattern (hand preference), whereas others showed consistency in laterality across all or most of the SH patterns they performed (hand specialization). At the group level, we found that, although their collective distribution of left versus right remained random, most subjects were either significantly but incompletely lateralized, or completely lateralized within particular SH patterns (pattern specialization), but not across all SH patterns (no handedness for SH behavior as a whole). As predicted by the task-complexity model, hand specialization and handedness were stronger in the coordinated bimanual SH patterns than in the unimanual patterns. We discuss the implications of our findings for the evolution of manual preferences in noninstrumental object manipulation versus stone tool use in nonhuman primates and hominins.  相似文献   

16.
The aim of the study was to determine the relation between motor abilities and belly dance performance in elementary school fifth- and sixth-grade female students. A battery of 19 motor tests was used in a sample of 96 students twice, i.e. at the beginning (initial measurement) and at the end (final measurement) of the academic year. On initial measurement, five factors were isolated by the motor space factor analysis: first factor of muscular-aerobic endurance; second factor integrating the strength of legs, coordination of foot and hand movement, and agility; third factor integrating explosive strength of the arms with speed and body coordination; fourth factor defined by flexibility (muscle tone regulation); and fifth factor integrating explosive strength of legs with equilibrium. On final measurement, five factors were isolated as well: first factor as a general one integrating coordination abilities, explosive strength of legs and flexibility; second factor defined by repetitive strength of the trunk and legs; third factor defined by rhythm coordination accompanied by flexibility; fourth factor predominantly defined by equilibrium (accompanied by explosive strength of throwing type and speed); and fifth factor predominantly defined by static strength of arms and legs (accompanied by arm movement frequency). On initial measurement, fourth factor responsible for muscle tone regulation and second factor integrating the strength of legs, coordination of movement frequency of arms and legs, and agility were found to be the best predictors of belly dance performance. In this setting, the tests of forward bow (flexibility) and sit-ups (repetitive strength of abdominal musculature) proved superior in differentiating high performance students and those less successful in belly dance. On final measurement, third factor named rhythm coordination (accompanied by muscle tone regulation) and second factor defined by repetitive strength of the trunk and legs were the best predictors of belly dance performance. In this setting, the tests of rhythm coordination, flexibility tests, tests of repetitive strength of the trunk and legs, and test of aerobic endurance proved superior in differentiating high performance and less successful students in belly dance.  相似文献   

17.
Improving production in short rotation coppice (SRC) plantations requires, among other elements, a proper understanding of clonal performance. Genotypic stability over a range of environments is a factor of concern for breeding and recommendation purposes. Most common stability measures can be embedded in a mixed‐model framework accounting for interaction and heterocedasticity in genotype‐by‐environment tables. Data from nine hybrid poplars of different taxonomic background were tested in four Mediterranean sites under three agronomic practices (control, herbicide application, and supplementary fertilization) for total biomass (TB), stem biomass (SB), and branch biomass (BB) at the end of the first rotation. Stability models (stability variance, Finlay–Wilkinson and Eberhart–Russell) were compared, also allowing for the definition of groups of genotypes with distinct taxonomic backgrounds and a priori different variabilities. Results showed that genotype‐by‐environment (GE) interactions were associated with factors inherent to evaluation sites rather than to the agronomic practices tested. Depending on biomass fraction, regression models provided appropriate stability measures. Highly reactive clones to improving environmental conditions (e.g., ‘AF2’) tended to show the largest mean TB. However, this was not always the case, as clone ‘Monviso’ showed both intermediate reactivity (i.e., stable sensu Eberhart–Russell) and enhanced overall performance. The taxonomic group was relevant for explaining stability patterns for SB. The stability assessment for BB indicated different patterns in biomass allocation. Present findings point to the feasibility of either exploiting specific adaptation (in which case hybrid type may play a relevant role) or searching for broadly adapted, stable material exhibiting good performance in Mediterranean conditions.  相似文献   

18.
A crucial insight into handwriting dynamics is embodied in the idea that stable, robust handwriting movements correspond to attractors of an oscillatory dynamical system. We present a phase dynamic model of visuomotor performance involved in copying simple oriented lines. Our studies on human performance in copying oriented lines revealed a systematic error pattern in orientation of drawn lines, i.e., lines at certain orientation are drawn more accurately than at other values. Furthermore, human subjects exhibit “flips” in direction at certain characteristic orientations. It is argued that this flipping behavior has its roots in the fact that copying process is inherently ambiguous—a line of given orientation may be drawn in two different (mutually opposite) directions producing the same end result. The systematic error patterns seen in human copying performance is probably a result of the attempt of our visuomotor system to cope with this ambiguity and still be able to produce accurate copying movements. The proposed nonlinear phase-dynamic model explains the experimentally observed copying error pattern and also the flipping behavior with remarkable accuracy.  相似文献   

19.
The main aim of this project was to study muscle activity patterns during steep uphill cycling (UC) (i.e., with a gradient of 20%) with (1) normal saddle geometry and (2) with adjusted saddle position ASP (i.e., moving the saddle forward and changing the tilt of the saddle by 20%). Based on our preliminary case study, we hypothesized that: (1) during 20% UC muscle activity patterns would be different from those of level cycling (LC) and (2) during 20% UC with ASP muscle activity patterns would resemble those of LC. Twelve trained male cyclists were tested on an electromagnetically braked cycle ergometer under three conditions with the same work rate (80% of maximal power output) and cadence (90 rpm): level (LC), 20% UC and 20% UC with ASP. Electromyographic signals were acquired from m. tibialis anterior (TA), m. soleus (SO), m. gastrocnemius (GC), m. vastus lateralis (VL), m. vastus medialis (VM), m. rectus femoris (RF), m. biceps femoris (BF) and m. gluteus maximus (GM). Compared to LC, 20% UC significantly modified both the timing and the intensity of activity of the selected muscles, while muscles that cross the hip joint were the most affected (RF later onset, earlier offset, shorter range of activity and decrease in peak amplitude of 34%; BF longer range of activity; GM increase in peak amplitude of 44%). These changes in EMG patterns during 20% UC were successfully counteracted by the use of ASP and it was interesting to observe that the use of ASP during 20% UC was perceived positively by all cyclists regarding both comfort and performance. These results could have a practical relevance in terms of improving performance during UC, together with reducing discomfort.  相似文献   

20.
The structural stability of wild-type horse prion protein   总被引:1,自引:0,他引:1  
Prion diseases (e.g. Creutzfeldt-Jakob disease (CJD), variant CJD (vCJD), Gerstmann-Straussler-Scheinker syndrome (GSS), Fatal Familial Insomnia (FFI) and Kuru in humans, scrapie in sheep, bovine spongiform encephalopathy (BSE or 'mad-cow' disease) and chronic wasting disease (CWD) in cattles) are invariably fatal and highly infectious neurodegenerative diseases affecting humans and animals. However, by now there have not been some effective therapeutic approaches or medications to treat all these prion diseases. Rabbits, dogs, and horses are the only mammalian species reported to be resistant to infection from prion diseases isolated from other species. Recently, the β2-α2 loop has been reported to contribute to their protein structural stabilities. The author has found that rabbit prion protein has a strong salt bridge ASP177-ARG163 (like a taut bow string) keeping this loop linked. This paper confirms that this salt bridge also contributes to the structural stability of horse prion protein. Thus, the region of β2-α2 loop might be a potential drug target region. Besides this very important salt bridge, other four important salt bridges GLU196-ARG156-HIS187, ARG156-ASP202 and GLU211-HIS177 are also found to greatly contribute to the structural stability of horse prion protein. Rich databases of salt bridges, hydrogen bonds and hydrophobic contacts for horse prion protein can be found in this paper.  相似文献   

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