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Jumpei Mizuno, Masashi Kawamura, and Minoru Hoshiyama

, & Marshall, 2015 ). Fu and Franz ( 2014 ) reported that µ suppression in the Rt-IFG and precentral region was specific to observation of hand movement from a first-person visual perspective compared with a third-person visual perspective. Significant activation of the contralateral sensorimotor cortex was

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Joy Khayat, Stéphane Champely, Ahmad Diab, Ahmad Rifai Sarraj, and Patrick Fargier

The present study aimed at examining the effect of mental calculation and number comparison on motor performance measured as the movement time of a fast manual-pointing movement. Three experiments, involving a total number of 65 undergraduate subjects, examined the effect of mental subtraction (complex) and, respectively, of (a) mental addition (simple or complex), (b) mental multiplication (simple or complex), and (c) the comparison of dot sets and number comparison. Each number was written in Arabic. The movement times were analyzed by using a multilevel linear mixed-effect model. The results showed significant improvement of manual-pointing movement performance only after the complex calculations and after number comparison. Possible implication of attentional mechanisms specific to this arithmetical activity is further discussed.

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Uta Sailer, Florian Güldenpfennig, and Thomas Eggert

This study investigated the effect of hand movements on behavioral and electro-physiological parameters of saccade preparation. While event-related potentials were recorded in 17 subjects, they performed saccades to a visual target either together with a hand movement in the same direction, a hand movement in the opposite direction, a hand movement to a third, independent direction, or without any accompanying hand movements. Saccade latencies increased with any kind of accompanying hand movement. Both saccade and manual latencies were largest when both movements aimed at opposite directions. In contrast, saccade-related potentials indicating preparatory activity were mainly affected by hand movements in the same direction. The data suggest that concomitant hand movements interfere with saccade preparation, particularly when the two movements involve motor preparations that access the same visual stimulus. This indicates that saccade preparation is continually informed about hand movement preparation.

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Jin H. Yan, Richard N. Hinrichs, V. Gregory Payne, and Jerry R. Thomas

This study was designed to examine Ihe developmental differences in the speed and smoothness of arm movement during overarm throwing. The second purpose of this investigation was to evaluate whether jerk is a useful measure in understanding children's overarm throwing. Fifty-one girls, aged 3 to 6 years, voluntarily participated in the study. Each subject threw tennis balls as hard as she could toward a large target on the wall. A 2-camera video system was used to obtain 3-D coordinates of the hand and ball using the DLT algorithm. The variables of velocity and jerk (for the hand and ball) served as the movement outcome measures. The age-associated differences in velocity and normalized jerk (absolute jerk standardized relative to movement time and distance) were examined by ANOVAs. The results supported the hypothesis that the older subjects demonstrated faster and smoother hand movements than their younger counterparts during the forward acceleration phase (from the beginning of forward motion to ball release). In addition, the correlation results indicated thai increased hand movement speed was associated with decreased movement jerk in older subjects, whereas increased hand speed was associated with increased jerk in younger subjects. The findings suggest that examining the jerk parameter (normalized or absolute jerk) is a useful and alternative approach to capture the variance of hand movement execution for children's overarm throwing.

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Agnès Roby-Brami, Johanna V.G. Robertson, Alexandra Roren, and Marie-Martine Lefèvre-Colau

This study explored the coordination between the components of the shoulder girdle (clavicle, scapula and humerus), and how they contribute to hand movement in the peri-personal space. Shoulder girdle motion was recorded in 10 healthy subjects during pointing movements to 9 targets in the peri-personal space, using electromagnetic sensors fixed to the trunk, scapula and upper arm. Most of the 9 degrees of freedom (DoF) of the shoulder girdle were finely scaled to target position. Principle component analysis revealed that the 6 DoF of scapula-thoracic motion were coordinated in three elementary patterns (protraction, shrug and lateral rotation). The ratio of gleno-humeral to scapulo-thoracic global motion was close to 2:1. A direct kinematic procedure showed that if no scapular motion occurred, the workspace would be reduced by 15.8 cm laterally, 13.7 cm vertically and 4.8 cm anteriorly. Scapulo-thoracic motion should be taken into account when investigating the physiology of upper-limb movements.

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Leonie Oostwoud Wijdenes, Eli Brenner, and Jeroen B.J. Smeets

This study set out to determine whether the fastest online hand movement corrections are only responses to changing judgments of the targets’ position or whether they are also influenced by the apparent target motion. Introducing a gap between when a target disappears and when it reappears at a new position in a double-step paradigm disrupts the apparent motion, so we examined the influence of such a gap on the intensity of the response. We found that responses to target perturbations with disrupted apparent motion were less vigorous. The response latency was 10 ms shorter when there was a gap, which might be related to the gap effect that has previously been described for initiating eye and hand movements.

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Melvyn Roerdink, Paulina J. M. Bank, C. (Lieke) E. Peper, and Peter J. Beek

Rhythmic limb movements are often anchored at particular points in the movement cycle. Anchoring may reveal essential task-specific information for motor control. We examined the effect of tracking mode (in-phase, antiphase) and gaze direction (left, right) on anchoring in visuomotor tracking with and without concurrent visual feedback of the hand movement. For in-phase tracking, anchoring was observed at the foveated reversal point whereas for antiphase tracking anchoring was observed at both reversals, suggesting the presence of two reference points instead of one. Anchoring at the foveated reversal reflected gaze anchoring (i.e., coalignment of hand and gaze) while anchoring at the nonfoveated reversal reflected visuomotor synchronization (i.e., the hand was steered to the nonfoveated reversal coincident with a target reversal at the point of gaze). We propose that the number and location of anchor points play a crucial role in the underlying control by providing reference values for error correction processes.

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Shannon D. Ringenbach, Romeo Chua, Brian K. V. Maraj, James C. Kao, and Daniel J. Weeks

Previous experiments involving discrete unimanual tasks have shown that individuals with Down syndrome (DS) have auditory/verbal-motor deficits. The present study investigated unimanual and bimanual continuous perceptual-motor actions in adults with DS. Ten adults with DS, 10 typical adults, and 10 children drew continuous circles at increasing periods bimanually and unimanually with each hand. Movement was paced by either a visual or an auditory metronome. The results revealed that for circle shape and coordination measures, children and adults were more accurate with the visual metronome, whereas adults with DS were more accurate with the auditory metronome. In the unimanual tasks, adults with DS displayed hand asymmetries on spatial measures. In the bimanual task, however, adults with DS adopted an in-phase coordination pattern and stability more similar to adults than children. These results suggest that bimanual coordination in adults with DS is functioning effectively despite hand asymmetries evident in unimanual performance.

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Ching-yi Wu, Shih-han Chou, Mei-ying Kuo, Chiung-ling Chen, Tung-wu Lu, and Yang-chieh Fu

Stroke patients are often left with hemiplegia or hemiparesis of the upper extremities, severely limiting the ability to perform bimanual and functional activities. No studies have investigated how stroke patients adapt their movements to changes in object size in functionally asymmetric bimanual tasks. The influence of object size on intralimb and interlimb coordination during an asymmetrical, functional bimanual task was examined in patients with left cerebral vascular accidents (LCVA) and healthy controls. Fourteen LCVA patients and 13 age-matched controls were instructed to reach to grasp a large and a small jar with the right/affected hand and to open the cap with the other hand. Movement kinematics was analyzed for intralimb coordination (spatial and temporal planning of reaching and grasping) and interlimb coordination (bimanual synchronization and temporal association of the hands). The results demonstrate a spatial adaptation of reaching in the affected hand to the object size and deficits in temporal planning of grasping with the affected hand to object size in the stroke patients. Movement adaptations of the unaffected hand in the stroke patients were similar to those in the healthy adults. Bimanual coordination was independent of object size for both groups.

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Marcos Gutiérrez-Davila, F. Javier Rojas, Carmen Gutiérrez-Cruz, Carlos García, and Enrique Navarro

The two-fold purpose of this study was to analyze the time required by a fencer to initiate a defensive action in response to a direct attack, which involves identifying when the defending fencer detects the just-noticeable difference, and, secondly, to assess the effect that an attacker’s rapid armed hand movement (feint attack) has on the time required to initiate a defensive move. Twenty-four elite fencers and a fencing master were included in the study. Four adapted force plates were installed on a scaffold used as a fencing piste. A 3D video analysis system recorded the location of 2 markers installed on the fencing master’s shoulder and sword. The results confirm that the defending fencer has a mean movement time of 0.353 ± 0.028 s to perform the defensive action, which provides an advantage over the attacking fencer. The velocity of movement in the peripheral visual field has no influence on the time required by elite fencers to initiate a defensive action. This confirms the crucial role that response inhibition processes play when nonrelevant actions are perceived. Kinematic analysis of markers suggests that the eye movements of elite fencers are not the only source of information used while observing an attack.