Prehension movements and motor development in children (original) (raw)

The development of coordination for reach-to-grasp movements in children

Experimental Brain Research, 2002

When adults reach to grasp stationary targets, movement kinematics (endpoint trajectories, interjoint coordination) are highly stereotyped and stable. The emergence of an optimal coordination for reaching involves mastering the redundant number of degrees of freedom while the body grows. Reaching has been well studied in healthy children under the age of 3 years. We characterised the development of coordination during reaching in children over the age of 3 years and identified age ranges in which stable patterns emerge. A random sample of 38 healthy children aged 4-11 years and nine adults participated in the study. They reached from the seated position with the dominant arm and grasped a cone placed at three distances in the forward sagittal plane in front of the body. Kinematic data from markers placed on the arm, head and trunk were recorded at 100 Hz (Optotrak Motion Analysis System). Immature patterns of reaching were characterised by increased variability in younger compared to older children. Hand trajectories became smoother and less variable with age. Interjoint coordination became more consistent, while trunk displacement and variability decreased with age. Only children between 8 and 10 years old had variability similar to adults. Our data suggest that different aspects of movement kinematics mature at different rates. However, our data do not support the idea of a sequential maturation of different biomechanical variables.

Development of reaching in infancy

Experimental Brain Research, 2005

The development of reaching for stationary objects was studied longitudinally in 12 human infants: 5 from the time of reach onset to 5 months of age, 5 from 6 to 20 months of age, and 2 from reach onset to 20 months of age. We used linear mixed-effects statistical modeling and found a gradual slowing of reach speed and a more rapid decrease of movement jerk with increasing age. The elbow was essentially locked during early reaching, but was prominently used by 6 months. Differences between infants were distributed normally and no evidence of different types of reachers was found. The current work combined with other longitudinal studies of infant reaching shows that the increase in skill over the first 2 years of life is seen, not by an increase in reaching speed, but by an increase in reach smoothness. By the end of the second year, the overall speed profile of reaching is approaching the typical adult profile where an early acceleration of the hand brings the hand to the region of the target with a smooth transition to a lower-speed phase where grasp is accomplished.

A Comparison of the Reach-To-Grasp Movement Between Children and Adults: A Kinematic Study

Developmental Neuropsychology, 2006

In this study, the reach-to-grasp movement of 5-year-old children was compared to that of adults. Participants were required to reach out and grasp objects, with and without on-line visual feedback. Object size and distance were covaried in a within-subjects design and it was found that for both groups, grip formation and reach kinematics were affected by the manipulation of either variable. Although there are a large number of similarities, a few differences between the two groups emerge. For the reaching component, the children revealed a longer movement duration and deceleration time and a lower maximum height of wrist trajectory than in adults. For the grasp component, the children, in both the vision and no-vision condition, show a maximal finger aperture larger than the adults. Further, the children of this study were able to scale their grip aperture according to object size when visual feedback during the movement was lacking. These findings suggest that children adopt different strategies than adults when planning a reach-to-grasp movement on the basis of object size, distance, and the predictability of visual feedback. The results are discussed in terms of the neural mechanisms underlying hand action and how these mechanisms may not be fully developed by the age of 5.

Development of manual dexterity in preschool children

Human Movement, 2018

Purpose. the aim of the study is to identify the changes in manual dexterity that occur in preschool children. Methods. the sample consisted of 79 healthy preschool children from Wroclaw, Poland. Manual dexterity was assessed twice: at the beginning of the school year and 9 months later at the end. the mean age of the group was 5.98 ± 0.45 years (initial assessment) and 6.86 ± 0.35 years (final assessment). Motor performance was evaluated with the Motorische Leistungsserie (MLS) test. Statistical analysis was carried out with ANOVA, and the percentage change of each parameter was calculated for the 9-month study period. Differences were considered significant at p < 0.05. Results. there was a 45% improvement in steadiness, which shows that the children were more able to hold their hands in a given position without shaking for a prolonged time. the children made significant progress in grasping and carrying small objects with fingers and placing them in sequential openings on the work surface of the test apparatus in a vertical line, performing better than adults in this regard. the results for the aiming subtest improved by over 20% in the children examined. the rate of tapping increased by almost 8%. Improvements in line tracing, however, were limited to the accuracy of performing the subtest. Conclusions. the results of the study reveal the need for longitudinal studies on this topic. Selected parameters of manual dexterity in preschool children improved from 4% to 45% over the course of the 9-month school year.

Effects of finger markers on the kinematics of reaching movements in young children and adults

Journal of applied biomechanics, 2007

Kinematic studies to date have not considered in what ways surface markers may affect the performance of the analyzed motion. This neglect is particularly apparent in studies of prehensile movements involving surface markers attached to the fingers. In order to specify any such effects, a range of kinematic parameters derived from simple reach-to-grasp movements, both with and without finger markers, by 3-year old children and adults were analyzed. Finger markers affected both the spatial and temporal nature of the children's reaching performance as revealed by a more temporally segmented reaching path, an age-atypically straighter reaching path, and an increased time to establish a pincer grip. The reaching movements made by the adults were unaffected in terms of the kinematic parameters employed.

Sensorimotor testing in children

2011 IEEE World Haptics Conference, 2011

This preliminary study investigated behaviorally the performance of a sample of young twins in a set of classical visuomotor tasks. The assessment was carried out using a small haptic interface used to produce force and record the hand trajectory during the execution of tasks requiring rapid and precise movements. The aim of the study was to evaluate the sensorimotor development across a wide age-range (6-13 years) in which dramatic changes in sensorimotor integration and motor skills occur. A mixed-effect analysis was performed in order to evaluate age-related effects and to check for reduction of residual variability within twins with respect to variability across all pairs of twins. We report both an effect of age and of parenthood when considering reaction times and control of position of the hand under perturbed environment. The ability of tracking a moving target and the velocity of information processing show a dependence on age but not on the parenthood factor. This study validates the methodology used to investigate the age effects on the motor behavior of children and promises to provide new insights in twin-studies.

Longitudinal study of unimanual actions and grasping forces during infancy

Infant Behavior and Development, 2012

Learning to grasp an object is an important milestone in neurological development during infancy. Several studies report development of reaching in infants but less attention is devoted to reaching with successful grasping and to development of grip force. This study investigates, in the first weeks of life, the development of palmar grasp both for assessment of unimanual/bimanual grasping actions in centrally and laterally placed objects and for measurement of exerted power grip force. We longitudinally examined ten infants from 18 weeks to 41 weeks, at 2-weeks intervals, with a toy placed in three positions (body midline, ipsilateral and contralateral shoulder). Our main aim was to study this development through an ecological approach. This was possible thanks to the use of the "biomechatronic gym", a new platform purposively developed for measuring reaching and grasping forces. These longitudinal trials showed a good level of acceptance and involvement by infants of the entire system. The results demonstrated a significant increase in unimanual power grip force between the 18th and 30th week followed by a flat period until the 41st week; we also ascertained an early tendency to play bimanually with centrally and laterally placed objects with a subsequent increase in all ages of unimanual successful power grasping both for central task and midline crossing. These developmental changes may be, in part, related to organism constraints such as maturation of the corticospinal tract.

Development of reaching during the first year: Role of movement speed

Journal of Experimental Psychology: Human Perception and Performance, 1996

When infants first learn to reach at about 4 months, their hand paths are jerky and tortuous, but their reaches become smoother and straighter over the first year. Here the authors consider the role of the underlying limb dynamics, which scale with movement speed, on the development of trajectory control. The authors observed 4 infants weekly and then biweekly from reach onset to 1 year. Improvements in trajectories were not linear, but showed plateaus and regressions in straightness and smoothness. When infants' nonreaching movements were fast, their reaches were also fast, and faster reaches were also less straight. This is consistent with an equilibrium trajectory form of control, where development involves the increasing ability to stabilize the trajectory against self-generated movement perturbations.

Body-scaled ratio as a control parameter for prehension in 5-to 9-year-old children

Developmental …, 1998

The purpose of the experiment was threefold: (a) To find evidence that grasping is body-scaled and thus remains invariant during development; (b) to seek evidence that the body-scaled ratio of cube and hand size serves as a control parameter for the phase transition from one-handed to two-handed grasping by identifying the presence of sudden jump, enhanced variance, multistability, and hysteresis; and (c) to examine whether the stability properties of the observed grasping patterns increase with age. Thirty-three children aged 5, 7, and 9 years old were required to grasp and lift 14 cardboard cubes of different sizes (2.2, 3.2, 4.2, etc. to 16.2 cm diameter). Three conditions were used: (a) an increasing condition with sizes ordered from the smallest size to the largest; (b) a decreasing condition, with the sizes ordered from the largest to the smallest; and (c) twice in a different random order. Video recordings were analyzed and scored for the percentage of one-handed grasps. The results showed that the shift from one-handed to two-handed grasping occurred at the same body-scale ratio between cube size and finger span for all three age groups. Evidence was found for the presence of a sudden jump, enhanced variance, multistability, and hysteresis, indicating that the body-scaled ratio of cube and hand size serves as a control parameter. No change with age for the stability properties of the grasping patterns were observed.