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1.
Right-handed human subjects of 4 different ages (5-6, 8-9, 11-12 yo. and adult subjects) performed simple graphical movements in a cyclic manner with maximal possible tempo. The movements differed with respect to their coordination and serial complexity and were performed by each hand while holding the stylus either by the fingers or the fist. It was found that cycle duration considerably decreased with age from the age of 5 to adulthood and the amount of the age-related gain in the performance rate depended on which hand (right vs. left) and/or grip (fingers vs. fist) was used to perform a movement. The rate of successive submovements neither changed substantially with age nor showed any lateral asymmetry however it did depend on the movement being performed and the grip being used. The results show that the age-related trend in the cyclic movements can almost entirely be accounted for by a reduction in the number of submovements in a cycle. The results are discussed in the view of the hypothesis that considers submovements to be the building blocks of a graphical movement. 相似文献
2.
This paper presents a mathematical model for the learning of accurate human arm movements. Its main features are that the
movement is the superposition of smooth submovements, the intrinsic deviation of arm movements is considered, visual and kinesthetic
feedback are integrated in the motion control, and the movement duration and accuracy are optimized with practice. This model
is consistent with the jerky arm movements of infants, and may explain how the adult motion behavior emerges from the infant
behavior. Comparison with measurements of adult movements shows that the kinematics of accurate movements are well predicted
by the model.
Received: 15 May 1997 / Accepted 5 December 1997 相似文献
3.
The purpose of this experiment was to explore the application of co-ordination dynamics to the analysis of discrete rather
than cyclical movements. Subjects, standing in a fixed position, were required to return table-tennis balls delivered to different
spatial locations in the direction of a fixed target. This was achieved in condition 1 by systematically scaling, from left
to right and vice versa, the `spatial location' of the ball–identified as a control parameter. In condition 2, the control
condition, the spatial location was varied randomly over the same range. The changes between regimes of the stroke co-ordination
pattern, defined at two different levels, (1) organisational – forehand or backhand drive, and (2) kinematic–the distance
of the bat at ball–bat contact relative to the leading edge of the table, were identified as collective variables, the values
of which changed spontaneously at the transition points exposed by the control parameter. The switch between regimes was shown
to be dependent upon the direction of scaling, i.e. a hysteresis effect was identified in both conditions. These findings
confirm that the conceptual and methodological frameworks of co-ordination dynamics can be applied, appropriately, to the
analysis of discrete movements. Moreover, it would seem that control parameter values (spatial location of the ball) do not
necessarily have to be scaled in a systematic way in order to produce the required effects.
Received: 22 April 1999 / Accepted in revised form: 8 May 2000 相似文献
4.
《Journal of Russian & East European Psychology》2013,51(5):78-84
The role of interhemispheric asymmetry in the conscious control of sensorimotor measurements of the Muller-Lyer illusion was investigated. We used this perceptual illusion as a phenomenon of consciousness to determine how error value depends on the contribution of the left and right hemisphere to the control of decision making. We compared the precision of the left- and right-hand movements on the touch screen during the measurement of segment length. It was found that the left and right hands controlled by two hemispheres in different ways made different errors during these measurements. The constant bias of right-hand movements is greater than that of the left hand. The conclusion is that the hemisphere primarily involved in movement control determines the dominant system of representation (metric vs. categorical) and the control type in decision making (automatic vs. conscious). The increase or decrease in accuracy of measurement of the illusory object depends on the increase or decrease of conscious control. 相似文献
5.
Studying plant root kinematics is important for understanding certain aspects of root growth and movement, which are strictly
correlated in plants. However, there is little available data on autonomous movements in plant roots, such as nutations, and
the data that are available are poorly described. We investigated the autonomous movements during growth in primary maize
roots by estimating the main kinematic parameters of nutations (i.e., the period of duration and amplitude) and the growth
rate. The estimations of nutation parameters were performed by developing dedicated methods, which are based on the analysis
of root tip displacement and tip velocity. The data relative to the tip displacements were obtained using tip tracing software
developed by our team specifically for this purpose. The results confirmed that the nutational phenomenon covers the continuous
range of periods and amplitudes, with certain dominant period-amplitude types, which we clustered into three groups: i) amplitudes
less than 0.1 mm and 4–16 min periods, ii) amplitudes less than 0.1 mm and 20–120 min periods, and iii) amplitudes greater
than 0.1 mm and 24–120 min periods. 相似文献
6.
Previous studies have suggested that the left and right hands have different specialties for motor control that can be represented as two agents in the brain. This study examined how coordinated movements are performed during bimanual reaching tasks to highlight differences in the characteristics of the hands. We examined motor movement accuracy, reaction time, and movement time in right-handed subjects performing a three-dimensional motor control task (visually guided reaching). In the no-visual-feedback condition, right-hand movement had lower accuracy and a shorter reaction time than did left-hand movement, whereas bimanual movement had the longest reaction time, but the best accuracy. This suggests that the two hands have different internal models and specialties: closed-loop control for the right hand and open-loop control for the left hand. Consequently, during bimanual movements, both models might be used, creating better control and planning (or prediction), but requiring more computation time compared to the use of one hand only. 相似文献
7.
The method of estimation of the coherence (Coh) function values of EEG rhythmic components disclosed the specific features
of functional associations of cortical regions during the performance of voluntary graphic cyclic movements under usual and
unusual conditions. A significant increase in the Coh function values of the α-rhythm was observed both in the contralateral
hemisphere and the symmetrical central and parietal cortical regions in adult subjects during right-hand movement performance
with open eyes (usual conditions); in this case the resulting functional associations included motor zone and cortical regions
responsible for visual information analysis and perception. During right- and left-hand movement performance with closed eyes
(unusual conditions), the mature-type functional organization had a bilateral character with interrelated activity focused
in the frontal regions that clearly demonstrated the function of these structures during formation of new motor programs.
The significant changes in cortical mechanisms of voluntary graphic movements were disclosed in young 7- to 8- and 9- to 10-year-old
schoolchildren. 相似文献
8.
Linda-Joy Lee Michel W. Coppieters Paul W. Hodges 《Journal of electromyography and kinesiology》2009,19(1):46-54
Anatomical and empirical data suggest that deep and superficial muscles may have different functions for thoracic spine control. This study investigated thoracic paraspinal muscle activity during anticipatory postural adjustments associated with arm movement. Electromyographic (EMG) recordings were made from the right deep (multifidus/rotatores) and superficial (longissimus) muscles at T5, T8, and T11 levels using fine-wire electrodes. Ten healthy participants performed fast unilateral and bilateral flexion and extension arm movements in response to a light. EMG amplitude was measured during 25 ms epochs for 150 ms before and 400 ms after deltoid EMG onset. During arm flexion movements, multifidus and longissimus had two bursts of activity, one burst prior to deltoid and a late burst. With arm extension both muscles were active in a single burst after deltoid onset. There was differential activity with respect to direction of trunk rotation induced by arm movement. Right longissimus was most active with left arm movements and right multifidus was most active with right arm movements. All levels of the thorax responded similarly. We suggest that although thoracic multifidus and longissimus function similarly to control sagittal plane perturbations, these muscles are differentially active with rotational forces on the trunk. 相似文献
9.
This paper tests the hypothesis that the central nervous system (CNS) learns to organize multijoint movements during a multijoint
‘bouncing pull’ task such that, after practice, motion of the anterior-posterior center of mass (CMAP) more closely resembles that of a conservative, one degree of freedom (DF), inverted pendulum model. The task requires standing
human subjects to produce precise peak pulling forces on a handle while maintaining balance – goals that can be easily accomplished
if movement is organized as in the model. Ten freely standing subjects practiced making brief, bouncing pulls in the horizontal
direction to target forces (20–80% of maximum) for 5 days. Pulling force, body kinematic and force plate data were recorded.
An eight-segment analysis determined sagittal-plane CM motion. We compared the effects of practice on the regression-based
fit between actual and model-simulated CMAP trajectories, and on measures of CMAP phase plane symmetry and parameter constancy that the model predicts. If the CNS learns to organize movements like the inverted
pendulum model, then model fit should improve and all other measures should approach zero after practice. The fit between
modeled and actual CMAP motion did not improve significantly with practice, except for moderate force pulls. Nor did practice increase phase plane
symmetry or parameter constancy. Specifically, practice did not decrease the differences between the pre-impact and rebound
positions or speeds of the CMAP, although speed difference increased with pulling force. CMAP at the end of the movement was anterior to its initial position; the anterior shift increased after practice. Differences
between the pre-pull and balance-recovery ankle torque (T
A) impulses were greater on day 5 and correlated with the anterior shift in CMAP. These results suggest that practice separately influenced the force production and balance recovery phases. A modified model
with damping could not explain the observed behaviors. A modified model using the actual time-varying TA profiles improved fit at lower force levels, but did not explain the increased postural shift after practice. We conclude
that the CNS does not learn to organize movements like the conservative, inverted pendulum model, but rather learned a more
complex form of organization that capitalized on more time-varying controls and more intersegmental dynamics. We hypothesize
that at least one additional DF and at least one time-varying parameter will be needed to explain fully how the CNS learns
to organize multijoint, bouncing pulls made while standing.
Received: 9 January 1997 / Accepted in revised form: 27 May 1997 相似文献
10.
Maozhong Zheng Qinli Wang Yan Teng Xiaohua Wang Feng Wang Tong Chen Jozef Šamaj Jinxing Lin David C. Logan 《Planta》2010,231(4):779-791
Strategic control of mitochondrial movements and cellular distribution is essential for correct cell function and survival.
However, despite being a vital process, mitochondrial movement in plant cells is a poorly documented phenomenon. To investigate
the roles of actin filaments and microtubules on mitochondrial movements, Picea wilsonii pollen tubes were treated with two microtubule-disrupting drugs, two actin-disrupting drugs and a myosin inhibitor. Following
these treatments, mitochondrial movements were characterized by multiangle evanescent wave microscopy and laser-scanning confocal
microscopy. The results showed that individual mitochondria underwent three classes of linear movement: high-speed movement
(instantaneous velocities >5.0 μm/s), low-speed movement (instantaneous velocities <5.0 μm/s) and variable-speed movement
(instantaneous velocities ranging from 0.16 to 10.35 μm/s). 10 nM latrunculin B induced fragmentation of actin filaments and
completely inhibited mitochondrial vectorial movement. Jasplakinolide treatment induced a 28% reduction in chondriome motility,
and dramatically inhibition of high-speed and variable-speed movements. Treatment with 2,3-butanedione 2-monoxime caused a
61% reduction of chondriome motility, and the complete inhibition of high-speed and low-speed movements. In contrast to actin-disrupting
drugs, microtubule-disrupting drugs caused mild effects on mitochondrial movement. Taxol increased the speed of mitochondrial
movement in cortical cytoplasm. Oryzalin induced curved mitochondrial trajectories with similar velocities as in the control
pollen tubes. These results suggest that mitochondrial movement at low speeds in pollen tubes is driven by myosin, while high-speed
and variable-speed movements are powered both by actin filament dynamics and myosin. In addition, microtubule dynamics has
profound effects on mitochondrial velocity, trajectory and positioning via its role in directing the arrangement of actin
filaments. 相似文献
11.
The present study focuses on two trajectory-formation models of point-to-point aiming movements, viz., the minimum-jerk and
the minimum torque-change model. To date, few studies on minimum-jerk and minimum torque-change trajectories have incorporated
self- or externally imposed end-point constraints, such as the direction and velocity with which a target area is approached.
To investigate which model accounts best for the effects on movement trajectories of such – in many circumstances – realistic
end-point constraints, we adjusted both the minimum-jerk and the minimum torque-change model so that they could generate trajectories
of which the final part has a specific direction and speed. The adjusted models yield realistic trajectories with a high curvature
near movement completion. Comparison of simulated and measured movement trajectories show that pointing movements that are
constrained with respect to final movement direction and speed can be described in terms of minimization of joint-torque changes.
Received: 7 July 1999 / Accepted in revised form: 8 January 2001 相似文献
12.
In theory, carbon is highly mobile in aquatic systems. Recent evidence from carbon stable isotopes of crabs (Parasesarma erythrodactyla and Australoplax tridentata), however, shows that in subtropical Australian waters, measurable carbon movement between adjacent mangrove and saltmarsh habitats is limited to no more than a few metres. We tested whether the pattern in crab δ13C values across mangrove and saltmarsh habitats was explained by crab movement, or the movement of particulate organic matter. We estimated crab movement in a mark–recapture program using an array of pitfall traps on 13 transects (a total of 65 traps) covering an area of 600 m2 across the interface of these two habitats. Over a 19-day period, the majority of crabs (91% for P. erythrodactyla, 93% for A. tridentata) moved <2 m from the place of initial capture. Crab movement cannot, therefore, explain the patterns in δ13C values of crabs. δ13C values of detritus collected at 2-m intervals across the same habitat interface fitted a sigmoidal curve of a similar form to that fitting the δ13C values of crabs. δ13C values of detritus were 2–4‰ more depleted in saltmarsh (−18.5±0.6‰), and 4–7‰ more depleted in mangroves (−25.9±0.1‰) than δ13C values of crabs recorded previously in each habitat. Assimilation by crabs of very small detrital fragments or microphytobenthos, more enriched in 13C, may explain the disparity in δ13C values. Nevertheless, the pattern in δ13C values of detritus suggests that crabs obtain their carbon from up to several metres away, but without themselves foraging more then a metre or so from their burrow. Such detailed measurements of carbon movement in estuaries provide a spatially explicit understanding of the functioning of food webs in saltmarsh and mangrove habitats. 相似文献
13.
Two behavioral goals are achieved simultaneously during forward trunk bending in humans: the bending movement per se and
equilibrium maintenance. The objective of the present study was to understand how the two goals are achieved by using a biomechanical
model of this task. Since keeping the center of pressure inside the support area is a crucial condition for equilibrium maintenance
during the movement, we decided to model an extreme case, called “optimal bending”, in which the movement is performed without
any center of pressure displacement at all, as if standing on an extremely narrow support. The “optimal bending” is used as
a reference in the analysis of experimental data in a companion paper. The study is based on a three-joint (ankle, knee, and
hip) model of the human body and is performed in terms of “eigenmovements”, i.e., the movements along eigenvectors of the
motion equation. They are termed “ankle”, “hip”, and “knee” eigenmovements according to the dominant joint that provides the
largest contribution to the corresponding eigenmovement. The advantage of the eigenmovement approach is the presentation of
the coupled system of dynamic equations in the form of three independent motion equations. Each of these equations is equivalent
to the motion equation for an inverted pendulum. Optimal bending is constructed as a superposition of two (hip and ankle)
eigenmovements. The hip eigenmovement contributes the most to the movement kinematics, whereas the contributions of both eigenmovements
into the movement dynamics are comparable. The ankle eigenmovement moves the center of gravity forward and compensates for
the backward center of gravity shift that is provoked by trunk bending as a result of dynamic interactions between body segments.
An important characteristic of the optimal bending is the timing of the onset of each eigenmovement: the ankle eigenmovement
onset precedes that of the hip eigenmovement. Without an earlier onset of the ankle eigenmovement, forward bending on the
extremely narrow support results in falling backward. This modeling approach suggests that during trunk bending, two motion
units – the hip and ankle eigenmovements – are responsible for the movement and for equilibrium maintenance, respectively.
Received: 1 July 1999 / Accepted in revised form: 23 October 2000 相似文献
14.
Animals swimming in tidal environments continuously interact with water currents which may either hinder or aid their movement.
It is difficult to observe the orientation of an organism relative to the current when it is swimming in the wild without
specialized telemetry; however, using the total recorded movement vector and the current vector, one can use vector analysis
to calculate the actual movement of the animal. Here, we apply this method to six tracks of green sturgeon (Acipenser medirostris) in the San Francisco Estuary, using current vectors derived from a hydrodynamic model. Three movements were near the surface
in deeper, high-current regions of the bay and three were near the bottom in shallow, low-current areas. The total displacement
over ground was faster at the surface (0.9 m sec−1 versus 0.5 m sec−1) and occurred in stronger currents (0.7 m sec−1 versus 0.4 m sec−1), but the swimming speeds of the fish were similar between surface and bottom movements (0.5 m sec−1 versus 0.6 m sec−1). All surface movements were in the direction of the current, and two of the fish also oriented closely to the flow. In contrast,
none of the three benthic movements were in the direction of the current, and two were oriented opposite to the flow. It seems
plausible that green sturgeon orient to and make use of water currents to efficiently move through tidal habitats, riding
the flow in high-current areas, and moving independently of, or even into, the flow in slower currents. 相似文献
15.
E. P. Man’kovskaya 《Neurophysiology》2006,38(3):197-200
We compared changes in the EEG indices in healthy dextral volunteers performing static force grasps by the arm. Three test
modes were used: (i) performance of two successive grasps by the dominant (right) arm (test A), (ii) performance of two successive
grasps by the subdominant (left) arm (test B), and (iii) performance of the grasps first by the right arm and then by the
left arm (test C). Fourteen, six, and nine persons took part in tests A–C, respectively. In the course of grasps performed
by the right and left arms, bilateral increases in synchronization within the alpha 1 and alpha 2 ranges were frequently observed
in occipital regions in both the first and repeated grasps (P < 0.05). Consecutive grasps by the right arm were accompanied by clear desynchronization in a few anterior and central leads.
Alpha 2 desynchronization was observed in both realizations of the left-arm grasps (test B) performed by some subjects, but
intragroup modifications were not significant in this case. The coherence coefficients of the alpha 2 rhythm in most cases
increased for symmetric leads from the right and left hemispheres in the course of grasps by both the right and left hands.
The effect of intensification of interhemisphere links was manifested in the anterior and central cortical regions; this fact
showed that interhemisphere interaction increases in the course of the static effort. Changes in the coherence coefficients
for the alpha 2 range in the performance of the grasp efforts by the right arm and the left arm were most clear in the posterotemporal
(P = 0.02), parietal (P = 0.05), and anterofrontal (P = 0.06) lead pairs. Thus, we demonstrated the dependence between the side of performance of the muscle effort in the mode
close to isometric and lateralization of the EEG modifications.
Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 235–238, May–June, 2006. 相似文献
16.
A geometric model for the myocardium: Biventricular wall stresses in normal and hypertrophied states
Assuming truncated ellipsoidal geometry for the right and left ventricles, a model is developed for the myocardium enabling
biventricular mechanical behavior to be studied. Employing pressure-volume data taken from normal dog hearts and from hearts
in which the pulmonary artery has been banded over periods of 2–40 weeks, it is shown that: (a) right ventricular wall stresses
are higher than left ventricular stresses; (b) right ventricular wall stress increases initially to a maximum after 3–4 weeks
followed by a decline to normal and even subnormal levels, attaining a minimum value at 32–33 weeks; (c) left ventricular
stresses behave in a similar manner, attaining their maximum and minimum levels after 7–8 weeks and 32–33 weeks respectively.
These results suggest that surgical or medical therapy in patients with hypertrophied ventricles might be more appropriate
during the period of wall stress reduction. 相似文献
17.
Movement irregularity is a feature of the upper motor neurone (UMN) syndrome which is difficult to measure. Average rectified jerk (ARJ) has been proposed as a measure of this movement irregularity, but ARJ depends upon the duration of movement. Since movements may be slower in UMN patients, duration dependence compromises ARJ as a measure of irregularity. A normalisation technique is proposed that generates a measure of movement irregularity which is independent of movement duration: normalised average rectified jerk (NARJ). This paper presents a validation of NARJ in the UMN syndrome. Nine control subjects, nine left hemiparetic stroke patients and nine right hemiparetic stroke patients were studied. Test movements comprised elbow extension/flexion in the horizontal plane; these were recorded with an electro-goniometer and accelerometer. The effectiveness of the normalisation technique has been demonstrated using trajectories of various durations; some of these were artificially generated from participants' trajectories, in order to preserve the movement profile. The variability of NARJ and ARJ have been compared in a sample of control subjects. NARJ has been criterion validated by correlation with expert subjective rating of irregularity in a heterogeneous set of trajectories. Construct validity has been tested by discrimination between movements of control subjects, left hemiparetic stroke patients and right hemiparetic stroke patients. When comparing trajectories of identical profile but two-fold difference in movement duration, NARJ differed only 2.6% whereas ARJ differed 706%. NARJ was less reproducible in healthy participants than ARJ: median non-parametric coefficients of variation for repeated movements were 55% and 41%, respectively. Spearman rank correlation coefficient for NARJ and expert rating was 0.92 (p<0.01). NARJ measurements on right hemiparetic patients differ significantly from those made on the control group (p<0.02); corresponding ARJ measurements do not attain statistical significance. NARJ is a valid measure of movement irregularity in the UMN syndrome. 相似文献
18.
M. V. Yoltukhovskii 《Neurophysiology》1999,31(3):154-159
Movement-related electrical reactions of neuronal units localized in field 2 of the frontal cortex were studied in albino
rats performing fast food-procuring movements under conditions of unrestrained behavior. According to the temporal characteristics
of the changes in the neuronal spike activity, three types of reactions were classified: (i) activation that forestalled the
movement initiation for 1.0–1.5 sec; (ii) activation or inhibition forestalling this beginning for 0.20–0.26 sec; and (iii)
activation in the course of a performed movement. Considerations about the involvement of the neurons of various cortical
layers in the mechanisms of programing, switching on, and current control of the efficiency of performance of food-procuring
movements are proposed, and the role of the frontal cortex in these processes is discussed. 相似文献
19.
Summary Ergovaline's role in the direct causation of fescue toxicosis first requires establishment of its dietary absorption. Therefore,
ergovaline movement across human intestinal cells was assessed using Caco-2 cells derived from human colon carcinoma. A pre-equilibrated
mixture of ergovaline/ergovalinine (60∶40 ratio of isomers) was added to the apical compartment, and isomer movements were
assessed by high-performance liquid chromatography (HPLC) of extracted media (initial pre-isomerized ergovaline concentrations
of 6 and 22 μM, two doses). Mathematical models for ergot alkaloid movement were developed. Rates of movement were not different for the
isomers. In the absence of cells, basal accumulation of isomers was essentially linear for 3 h regardless of loading concentration,
after which basal accumulation of ergovaline/ergovalinine plateaued. Rates of ergovaline/ergovalinine movement in the presence
of cells slowed to about 25% the rate of movement in the absence of cells (22 μM, kt=0.0133 no cells, 0.0036 with cells, P<0.05). Mass transfer rate was 7.5 ng·cm−2·min−1 and was similar to that reported for ergovaline using a parabiotic chamber with sheep omasum. After 6 h in the presence of
cells, ∼25 and 40% of the total ergovaline/ergovalinine administered had accumulated in the basal compartment for 6.6 and
22 μM treatments, respectively. Ergovaline and its naturally occurring isomer, ergovalinine, readily crossed intestinal cells intact
and at similar rates. Either isomer, or a combination of both, could be involved in the pathogenesis of fescue toxicosis at
sites distal to the intestine. 相似文献
20.
Reflection of Anxiety in the Characteristics of Evoked EEG Potentials in 10- to 11-Year-Old Children
We studied the peculiarities of the amplitude/time parameters of evoked EEG potentials (EPs) and event-related potentials
(ERPs) in 10- to 11-year-old children characterized by low and high anxiety levels. The latter levels were estimated using
the scale of the manifest anxiety test of Prikhozhan and projective techniques (“House–Tree–Person,” HTP, and the Lüscher
color test). For children with a high anxiety level, the amplitudes of the following EP components and ERPs were lower than
those in low-anxiety children of the same age: P1 (predominantly in the occipital region of the left hemisphere), P2 (in the
right occipital region), and Р300 wave (in different loci of both hemispheres). In high-anxiety children, we also more frequently
observed increased amplitudes of the N2 component in the left parietal and right occipital regions. High-anxiety individuals
were characterized by longer latencies of component P1 (mostly in the right frontal and left central regions) and, at the
same time, shorter latencies of component N1 (in the parietal and occipital regions of the left hemisphere and also in the
right temporal region). Thus, we found that the amplitude/time characteristics of a few EP components and ERPs in children
with high anxiety levels differ statistically significantly from the parameters of corresponding EPs/ERPs in individuals of
the same age but with low anxiety levels. 相似文献