Effects of postural support on eye hand interactions across development

Development of eye-hand coordination in typically developing children and adolescents assessed using a reach-to-grasp sequencing task

Eye-hand coordination is required to accurately perform daily activities that involve reaching, grasping and manipulating objects. Studies using aiming, grasping or sequencing tasks have shown a stereotypical temporal coupling pattern where the eyes are directed to the object in advance of the hand movement, which may facilitate the planning and execution required for reaching. While the temporal coordination between the ocular and manual systems has been extensively investigated in adults, relatively little is known about the typical development of eye-hand coordination. Therefore, the current study addressed an important knowledge gap by characterizing the profile of eye-hand coupling in typically developing school-age children (n = 57) and in a cohort of adults (n = 30). Eye and hand movements were recorded concurrently during the performance of a bead threading task which consists of four distinct movements: reach to bead, grasp, reach to needle, and thread. Results showed a moderate to high correlation between eye and hand latencies in children and adults, supporting that both movements were planned in parallel. Eye and reach latencies, latency differences, and dwell time during grasping and threading, showed significant age-related differences, suggesting eye-hand coupling becomes more efficient in adolescence. Furthermore, visual acuity, stereoacuity and accommodative facility were also found to be associated with the efficiency of eye-hand coordination in children. Results from this study can serve as reference values when examining eye and hand movement during the performance of fine motor skills in children with neurodevelopmental disorders.

Evaluation of the effects of using a baby walker on trunk control and motor development

Objective

This study aimed to evaluate the effects of the use of baby walkers on trunk control and motor development in typically developing children.

Material and methods

Demonstrating standard developmental steps, 29 children (14 females, 15 males; mean age 10±1 month) who used a baby walker and 19 children (10 females, 9 males; mean age 10±1 month) who did not use a baby walker were included. Motor skills were assessed using the Alberta Infant Motor Scale and trunk control using Segmental Assessment of Trunk Control.

Results

The motor development scores and trunk balance scores were found significantly lower in infants who used a baby walker compared with those not using a baby walker.

Conclusion

It was concluded that the use of baby walkers might adversely affect the motor development of infants and this may be due to impaired trunk control.

The effect of standing desks on manual control in children and young adults

The aim of the present study was to establish if and how the additional postural constraint of standing affects accuracy and precision of goal directed naturalistic actions. Forty participants, comprising 20 young adults aged 20-23 years and 20 children aged 9-10 years completed 3 manual dexterity tasks on a tablet laptop with a handheld stylus during two separate conditions (1) while standing and (2) while seated. The order of conditions was counterbalanced across both groups of participants. The tasks were (1) a tracking task, where the stylus tracked a dot in a figure of 8 at 3 speeds, (2) an aiming task where the stylus moved from dot to dot with individual movements creating the outline of a pentagram and (3) a tracing task, where participants had to move the stylus along a static pathway or maze. Root mean squared error (RMSE), movement time and path accuracy, respectively, were used to quantify the effect that postural condition had on manual control. Overall adults were quicker and more accurate than children when performing all 3 tasks, and where the task speed was manipulated accuracy was better at slower speeds for all participants. Surprisingly, children performed these tasks more quickly and more accurately when standing compared to when sitting. In conclusion, standing at a desk while performing goal directed tasks did not detrimentally affect children's manual control, and moreover offered a benefit.

Children's head movements and postural stability as a function of task

Manual dexterity and postural control develop throughout childhood, leading to changes in the synergistic relationships between head, hand and posture. But the postural developments that support complex manual task performance (i.e. beyond pointing and grasping) have not been examined in depth. We report two experiments in which we recorded head and posture data whilst participants simultaneously performed a visuomotor task. In Experiment 1, we explored the extent to which postural stability is affected by concurrently performing a visual and manual task whilst standing (a visual vs. manual-tracking task) in four age groups: 5-6 years (n = 8), 8-9 years (n = 10), 10-11 years (n = 7) and 19-21 years (n = 9). For visual tracking, the children's but not adult's postural movement increased relative to baseline with a larger effect for faster moving targets. In manual tracking, we found greater postural movement in children compared to adults. These data suggest predictive postural compensation mechanisms develop during childhood to improve stability whilst performing visuomotor tasks. Experiment 2 examined the extent to which posture is influenced by manual activity in three age groups of children [5-6 years (n = 14), 7-8 years (n = 25), and 9-10 years (n = 24)] when they were seated, given that many important tasks (e.g. handwriting) are learned and performed whilst seated. We found that postural stability varied in a principled manner as a function of task demands. Children exhibited increased stability when tracing a complex shape (which required less predictive postural adjustment) and decreased stability in an aiming task (which required movements that were more likely to perturb posture). These experiments shed light on the task-dependant relationships that exist between postural control mechanisms and the development of specific types of manual control.

A systematic review of sensorimotor function during adolescence: a developmental stage of increased motor awkwardness?

BACKGROUND

Although adolescent motor awkwardness and increased injury susceptibility have often been speculated and researched, studies regarding adolescent regressions in motor control have yielded inconsistent conclusions. Thus, the relationship between adolescent maturation and injury risk remains unclear. The purpose of this study was to systematically review the literature relative to two questions: (1) Which sensorimotor mechanisms are not fully mature by the time children reach adolescence? and (2) Is adolescence a period when children exhibit delays or regressions in sensorimotor mechanisms?

METHODS

Systematic searches for keywords were performed in February 2010 using PubMed MEDLINE (from 1966), CINAHL (from 1982) and SPORTDiscus (from 1985) databases. Articles were reviewed relative to predetermined criteria, and the methodological quality of each included study was assessed.

RESULTS

The search identified 2304 studies, of which 33 studies met the inclusion criteria. All 33 identified studies provided results associated with Question 1, 6 of which also yielded results pertaining to Question 2. The search results indicated that many aspects of sensorimotor function continue to mature throughout adolescence, and at least some children experience delays or regressions in at least some sensorimotor mechanisms. The results also exposed several significant weaknesses in our knowledge base.

CONCLUSION

The identified knowledge gaps are critical barriers because they hinder methods for identifying children at high risk and diminish the efficacy of targeted prevention programmes. Implications regarding research on adolescent injury risk are discussed and recommendations for future research such as improved methodological designs and integration of non-linear analyses are provided.

Refinement, reliability, and validity of the segmental assessment of trunk control

PURPOSE

The Segmental Assessment of Trunk Control (SATCo) provides a systematic method of assessing discrete levels of trunk control in children with motor disabilities. This study refined the assessment method and examined reliability and validity of the SATCo.

METHODS

After refining guidelines, 102 video recordings of the SATCo were made of 8 infants with typical development followed longitudinally from 3 to 9 months of age and 24 children with neuromotor disability with a mean age of 10 years 4 months. Eight researchers independently scored recordings.

RESULTS

Intraclass correlation coefficient values for interrater reliability were more than 0.84 and 0.98 across all data sets and all aspects of control. Tests of concurrent validity with the Alberta Infant Motor Scales resulted in coefficients ranging from 0.86 to 0.88.

CONCLUSION

The SATCo is a reliable and valid measure allowing clinicians greater specificity in assessing trunk control.

Eye hand coordination in children with cerebral palsy

Reaching to grasp an object of interest requires complex sensorimotor coordination involving eye, head, hand and trunk. While numerous studies have demonstrated deficits in each of these systems individually, little is known about how children with cerebral palsy (CP) coordinate multiple motor systems for functional tasks. Here we used kinematics, remote eye tracking and a trunk support device to examine the functional coupling of the eye, head and hand and the extent to which it was constrained by trunk postural control in 10 children with CP (6-16 years). Eye movements in children with CP were similar to typically developing (TD) peers, while hand movements were significantly slower. Postural support influenced initiation of hand movements in the youngest children (TD & CP) and execution of hand movements in children with CP differentially depending on diagnosis. Across all diagnostic categories, the most robust distinction between TD children and children with CP was in their ability to isolate eye, head and hand movements. Results of this study suggest that deficits in motor coordination for accurate reaching in children with CP may reflect coupled eye, head, and hand movements. We have previously suggested that coupled activation of effectors may be the default output for the CNS during early development.