Towards a broader scope of biomechanics in developmental studies: a commentary on Jensen (2005)

In this article, we discuss where biomechanical analysis can contribute to our understanding of motor development, and more particularly in what ways biomechanics can contribute to (1) explaining the universal sequence in motor milestones; (2) explaining variations in developmental sequence between individuals; (3) understanding the impact of context on the actions of an individual; and (4) understanding, preventing, and managing chronic disabilities. In our view, biomechanics is concerned with the dynamics of the musculo‐skeletal system (MSS) and thus provides insights in the way motion is affected by the activation of muscles and the mechanical interaction between the MSS and the environment. Biomechanical analysis is important in understanding the development of actions that depend on the perceptual‐motor loop although it cannot provide a full account of the changes in the behaviour. The contributions and limitations of specific biomechanical analyses such as the inverse and forward dynamical models are discussed in the light of the article of Jensen (2005). Copyright © 2005 John Wiley & Sons, Ltd.     

Adding pieces to the puzzle: a commentary

In Jensen's theme paper she did an excellent job of outlining and explaining ways in which motor developmentalists can use the tools of biomechanics and engineering to address research questions. We extend her thorough efforts in two ways. First, we highlight the communication value provided by the precision of biomechanics terminology, and second, we reinforce the need to embed motion (the kinematics and kinetics) in context and function in order to understand the complexity of behaviour. We illustrate how one biomechanical tool, mechanical models, can facilitate this and provide insight to the development of control. Copyright © 2005 John Wiley & Sons, Ltd.     

A Web-based digitized video image system for the study of motor coordination

A Web-based instructional project for the study of motor coordination is presented. The project includes two components: a tutorial on motor coordination and an interactive digitized video image system developed for the analysis of motion, including topics in biomechanics, motor coordination, motor control, and motor skill. This interactive system allows for the quantitative analysis of stored video images that are accessible from the World-Wide Web. The use of this digitizing system for the measurement and analysis of human locomotion coordination patterns is presented.     

Is a quantitative approach useful in the comparison of spontaneous movements in fullterm and preterm infants?

Spontaneous motility in the first six months of infancy has been examined over the last few decades using both qualitative and quantitative techniques. The major focus of the quantitative research has been to investigate a dynamic systems approach to understanding motor development, and has primarily examined normal development in fullterm infants. Recently, there have been several papers comparing spontaneous kicking in fullterm and preterm infants. These studies were designed to identify developmental differences that may indicate a risk of later motor disability. There has, however, been criticism that the quantitative approach fails to detect developmental differences that are useful in early identification of disability, unlike qualitative approaches which use the principles of Gestalt perception to examine the quality of the total movement pattern in young infants. The current paper describes both qualitative and quantitative techniques and reviews recent studies using motion analysis to compare early motor development in fullterm and preterm infants. New evidence is provided to suggest that the quantitative approach may not only be useful in detecting infants at risk of motor disability, but may also be useful in identifying the underlying processes that determine normal and abnormal motor outcomes.     

Trajectories and predictors of developmental skills in healthy twins up to 24 months of age

Background

Low birth weight and low 5-min Apgar scores have been associated with developmental delay, while older maternal age is a protective factor. Little is known about trajectories and predictors of developmental skills in infant twins, who are generally born with lower birth weights, lower Apgar scores and to older mothers.

Methods

Developmental skills were assessed at 3, 6, 9, 12, 18 and 24 months using the Ages and Stages Questionnaires in 152 twins from the Birmingham Registry for Twin and Heritability Studies. Multilevel spline and linear regression models (adjusted for gestational age, gender, maternal age) were used to estimate developmental trajectories and the associations between birth weight, maternal age and Apgar scores on developmental skills.

Results

Twins performed worse than singletons on communication, gross motor, fine motor, problem solving and personal-social skills (p < 0.001). Twins caught up around 6 months (score within −1 standard deviation of norm), except on gross motor skills, which did not catch up until after the age of 12 months. A one-year increase in maternal age was significantly associated with decreases in gross motor and personal–social z-scores of up to −0.09, whereas one unit increases in Apgar score increased z-scores up to 0.90 (p < 0.01).

Conclusions

Healthy twins should be considered at a higher risk for developmental delay. Whether these results are comparable to preterm singletons, or whether there are twin-specific issues involved, should be further investigated in a study that uses a matched singleton control group.     

Specialization of the motor system in infancy: from broad tuning to selectively specialized purposeful actions

In executing purposeful actions, adults select sufficient and necessary limbs. But infants often move goal‐irrelevant limbs, suggesting a developmental process of motor specialization. Two experiments with 9‐ and 12‐month‐olds revealed gradual decreases in extraneous movements in non‐acting limbs during unimanual actions. In Experiment 1, 9‐month‐olds produced more extraneous movements in the non‐acting hand/arm and feet/legs than 12‐month‐olds. In Experiment 2, analysis of the spatiotemporal dynamics of infants’ movements revealed developmental declines in the spatiotemporal coupling of movements between acting and non‐acting arms. We also showed that the degree of specialization in infants’ unimanual actions is associated with individual differences in motor experience and visual attention, indicating the experience‐dependent and broad functional nature of these developmental changes. Our study provides important new insights into motor development: as in cognitive domains, motor behaviours are initially broadly tuned to their goal, becoming progressively specialized during the first year of life.     

Unilateral implicit motor learning deficit in developmental dyslexia

It has been suggested that developmental dyslexia involves various literacy, sensory, motor skill, and processing speed deficits. Some recent studies have shown that individuals with developmental dyslexia exhibit implicit motor learning deficits, which may be related to cerebellar functioning. However, previous studies on implicit motor learning in developmental dyslexics have produced conflicting results. Findings from cerebellar lesion patients have shown that patients' implicit motor learning performance varied when different hands were used to complete tasks. This suggests that dyslexia may have different effects on implicit motor learning between the two hands if cerebellar dysfunction is involved. To specify this question, we used a one-handed version of a serial reaction time task to compare the performance of 27 Chinese children with developmental dyslexics with another 27 age-matched children without reading difficulties. All the subjects were students from two primary schools, Grades 4 to 6. The results showed that children with developmental dyslexic responded more slowly than nondyslexic children, and exhibited no implicit motor learning in the condition of left-hand response. In contrast, there was no significant difference in reaction time between two groups of children when they used the right hand to respond. This finding indicates that children with developmental dyslexia exhibited normal motor skill and implicit motor learning ability provided the right hand was used. Taken together, these results suggested that Chinese children with developmental dyslexia exhibit unilateral deficits in motor skill and implicit motor learning in the left hand. Our findings lend partial support to the cerebellar deficit theory of developmental dyslexia.     

Biomechanics Concept Inventory

A third version of a biomechanics concept inventory was developed and administered to 41 kinesiology majors before and after an introductory biomechanics class to build a larger pool of questions for course evaluation. The test measured understanding of four prerequisite and eight competencies based on national standards. Mean and standard deviation normalized gain was 29% (21) of maximum possible improvement and was similar to previous versions of the test given to students at the same university. Biomechanics instructors can use questions from all versions of the Biomechanics Concept Inventory to customize tests for evaluating instructional techniques in biomechanics.     

Motor planning between 4 and 7 years of age: Changes linked to executive functions

In the present study, we adopted the conceptual frameworks of Miyake et al. (2000) (organization of executive functions) and Sergeant (2000) (linking executive function to motor behaviour) to assess developmental changes in executive functions and motor behaviour, using a planning task with a sample of 4–7-years old children. More precisely, the aim of the study was to characterize the development of motor response planning between the ages of 4 and 7 as a measure of the integration of multiple executive function processes, namely inhibition, shifting and working memory, and to gain insight into the concurrent developmental contributions of these processes. Participants were divided into two groups: group 1 was composed of 24 children aged 4–5 years and group 2 was composed of 20 children aged 6–7 years. Each participant took tests for shifting, inhibition, working memory and motor planning (the egg-planning task). Our results suggest that the egg-planning task requires the inhibition of a pre-potent but inappropriate response, and to a lesser extent the manipulation of working memory strategies. These results are discussed in relation to the development of each executive function component.     

The Gesell developmental schedule in hispanic low-birth weight infants during the first year of life

The Gesell Schedule was administered to 143 low birthweight, high-risk, Hispanic infants of low-socioeconomic status to determine if this test was appropriate for this population. All but 5 were preterms, 73 females, 70 males. The infants were evaluated at 20 and 40 weeks corrected chronological age (CCA). The Gesell appears to be a useful developmental test for this population. Values for the overall developmental quotient (DQ) did not deviate from the Gesell norms, despite the infants' relatively poor growth pattern. Slight deviations from the norm in gross motor, fine motor, and language subscales were observed at 40 weeks CCA. Repeated measure analyses of variance revealed a significant decline in overall developmental, language, and fine motor quotients from 20 to 40 weeks. Birth-weight (BW) and small-for-gestational-age (SGA) categories influenced the outcome.     

发展性协调障碍的神经机制

发展性协调障碍是一种特殊的发育障碍, 它的一个显著特征是动作协调困难, 这种障碍影响着5%~8%学龄儿童的学业成绩和日常生活。发展性协调障碍常常与其他类型的学习困难并存。发展性协调障碍的病因非常复杂, 这种障碍与一定程度的视觉空间认知能力受损有关, 早期精细运动技能发育与脑神经发育进程可能存在时间的重合。近年来, 研究者们试图探索影响发展性协调障碍的神经基础, 并先后提出不同的神经关联假说。这些理论假说主要涉及到小脑、顶叶、胼胝体、基底神经节和大脑白质等脑区。本文全面回顾了该领域研究的最新进展, 并提出未来研究应该关注的方向与问题。     

Motor sequence learning in children with recovered and persistent developmental stuttering: preliminary findings

PurposePrevious studies have associated developmental stuttering with difficulty learning new motor skills. We investigated non-speech motor sequence learning in children with persistent developmental stuttering (CWS), children who have recovered from developmental stuttering (CRS) and typically developing controls (CON).MethodsOver the course of two days, participants completed the Multi-Finger Sequencing Task, consisting of repeated trials of a10-element sequence, interspersed with trials of random sequences of the same length. We evaluated motor sequence learning using accuracy and response synchrony, a timing measure for evaluation of sequencing timing. We examined error types as well as recognition and recall of the repeated sequences.ResultsCWS demonstrated lower performance accuracy than CON and CRS on the first day of the finger tapping experiment but improved to the performance level of CON and CRS on the second day. Response synchrony showed no overall difference among CWS, CRS and CON.Learning scores of repeated sequences did not differ from learning scores of random sequences in CWS, CRS and CON. CON and CRS demonstrated an adaptive strategy to response errors, whereas CWS maintained a high percentage of corrected errors for both days.ConclusionsOur study examined non-speech sequence learning across CWS, CRS and CON. Our preliminary findings support the idea that developmental stuttering is not associated with sequence learning per se but rather with general fine motor performance difficulties.     

Systematic mapping of developmental milestones in wild chimpanzees

Postnatal development is protracted relative to lifespan in many primates, including modern humans (Homo sapiens), facilitating the acquisition of key motor, communication and social skills that can maximize fitness later in life. Nevertheless, it remains unclear what evolutionary drivers led to extended immature periods. While the developmental milestone literature is well established in humans, insight we can gain from one‐species models is limited. By comparing the timing of relatable developmental milestones in a closely related species, the chimpanzee (Pan troglodytes), we can gain further understanding of the evolution of such an extended developmental phase. To date, few studies have specifically attempted to estimate developmental milestones in a manner comparable to the human literature, and existing studies lack sufficient sample sizes to estimate which milestones are more plastic with higher inter‐individual variation in the timing of their emergence. Here, we describe the emergence of gross motor, fine motor, social interaction and communication traits from a longitudinal sample of 19 wild chimpanzee infants (8 females and 11 males), Taï National Park, Côte d’Ivoire. Gross motor traits emerged at a mean of 4 months, communication traits at 12 months, social interaction traits at 14 months and fine motor traits at 15 months, with later emerging milestones demonstrating greater inter‐individual variation in the timing of the emergence. This pattern of milestone emergence is broadly comparable to observations in humans, suggesting selection for a prolonged infantile phase and that sustained skills development has a deep evolutionary history, with implications for theories on primate brain development.     

Verbal actions of physiotherapists to enhance motor learning in children with DCD

In this study, the motor teaching principles taxonomy (MTPT) was developed to investigate which teaching principles physiotherapists use to treat children with developmental coordination disorder during Neuromotor Task Training (NTT). In NTT, special attention is paid to the best ways to instruct and provide feedback. Based on motor learning theory and video observations of NTT treatments, teaching principles aimed at improving motor learning were categorised into three categories: giving instruction, providing or asking feedback, and sharing knowledge. The MTPT's reliability and validity were satisfactory. Therapists gave instructions very frequently. In addition, the principle frequency showed hardly any correlation with the children's initial motor performance level, indicating that the principles used are not related to the child's entry level.     

Myrtle McGraw''s Unrecognized Conceptual Contribution to Developmental Psychology

In the late nineteenth century and through much of the twentieth century, the notion of the early developmental autonomy of motor behavior pervaded behavioral embryology and the developmental psychology of infant behavior. In the midst of this predeterministic climate of opinion concerning motor development, Myrtle McGraw briefly and tentatively broached the probabilistic epigenetic notion of a bidirectional or reciprocal relationship between structural maturation and function, whereby structural maturation of the nervous system is influenced by functional activity as well as the other way around. Myrtle McGraw thus anticipated our current understanding of the role of experience in the cortical and motor maturation of infants in the first year of postnatal life. It is all the more remarkable that she made this contribution when the theoretical climate of opinion was epitomized by predeterministic epigenetic thinking. In the same vein, McGraw's second unrecognized contribution is her clear formulation of a suitably flexible critical period concept in 1935, one that is consonant with our current understanding.     

Focus on variability: New tools to study intra-individual variability in developmental data

In accordance with dynamic systems theory, we assume that variability is an important developmental phenomenon. However, the standard methodological toolkit of the developmental psychologist offers few instruments for the study of variability. In this article we will present several new methods that are especially useful for visualizing and describing intra-individual variability in individual time-serial data of repeated observations. In order to illustrate these methods, we apply them to data of early language development. After reviewing the common techniques and measures, we present new methods that show variability in developmental time-series data: the moving min–max graph, and the progmax–regmin graph. In addition, we demonstrate a technique that is able to detect sudden increases of variability: the critical frequency method. Also, we propose a technique that is based on a central assumption of the measurement-error-hypothesis: namely the symmetric distribution of error. Finally, as traditional statistical techniques have little to offer in testing variability hypotheses, we examine the possibilities that are provided by random sampling techniques. Our aim with the present discussion of variability and the demonstration of some simple yet illustrative techniques is to help researchers focus on rich additional sources of information that will lead to more interesting hypotheses and more powerful testing procedures, adapted to the unique nature of developmental data.     

Fine motor skill proficiency in typically developing children: On or off the maturation track?

Fine motor skill proficiency is an essential component of numerous daily living activities such as dressing, feeding or playing. Poor fine motor skills can lead to difficulties in academic achievement, increased anxiety and poor self-esteem. Recent findings have shown that children’s gross motor skill proficiency tends to fall below established developmental norms. A question remains: do fine motor skill proficiency levels also fall below developmental norms? The aim of this study was to examine the current level of fine motor skill in Irish children. Children (N = 253) from 2nd, 4th and 6th grades (mean age = 7.12, 9.11 and 11.02 respectively) completed the Fine Motor Composite of the Bruininks Oseretsky Test of Motor Proficiency 2nd Edition (BOT-2). Analysis revealed that only 2nd grade children met the expected level of fine motor skill proficiency. It was also found that despite children’s raw scores improving with age, children’s fine motor skill proficiency was not progressing at the expected rate given by normative data. This leads us to question the role and impact of modern society on fine motor skills development over the past number of decades.     

Motor response inhibition and execution in the stop-signal task: development and relation to ADHD behaviors.

The main aim of this study was to investigate the developmental course of motor response inhibition and execution as measured by the stop-signal task in a population-based sample of 525 4- to 12-year-olds. A further aspiration of the study was to enhance the limited knowledge on how the various stop-signal measures relate to ADHD behaviors in a normal sample. We also wanted to contribute to the theoretical understanding of the various stop-signal measures by examining the relations between the stop-signal measures and performance on tasks reflecting other aspects of response inhibition and execution. Our results showed that the ability to inhibit as well as to execute a motor response as measured by the stop-signal task improved with age during childhood. Of specific interest are the findings suggesting that this task captures the development of motor response inhibition in the late preschool years (age 5 years). Both of the inhibition measures derived from the stop-signal task (i.e., SSRT and probability of inhibition) related significantly to teacher ratings of inattention as well as to performance on tasks tapping other aspects of inhibition. The data provided by this study have thus contributed to the scarce knowledge on early development of motor response inhibition, as well as suggested that the stop-signal task may be a valuable tool for capturing deficient motor response inhibition in ADHD behaviors in normal samples.     

Development of motor imagery and anticipatory action planning in children with developmental coordination disorder – A longitudinal approach

Children with impaired motor coordination (or Development Coordination Disorder – DCD) have difficulty with the predictive control of movements, evidenced by cross-sectional studies that show impaired motor imagery and action planning abilities. What remains unclear is whether this deficit in predictive control reflects immaturity of the motor system (a developmental delay) or some deviation from normal development (a disorder). To advance this discussion the present study used a longitudinal design to examine the development of motor imagery and action planning in children with DCD. Thirty children were included in the DCD group (aged 6–11 years) and age- and gender-matched to 30 controls. The DCD group had a mABC-2 score ≤ 16th percentile, the control group > 20th percentile. Motor imagery was assessed with the hand rotation task, action planning with a test for end-state comfort. Children participated in three measurements, with one year in between measurements. Results showed that children with DCD were slower and less accurate than their typically developing peers in all subsequent years but were able to improve their motor imagery ability over time. Furthermore, children with DCD showed less planning for ESC at the start of the present study, but were able to catch up with their peers during two-year follow up. These results exemplify that improvement of motor imagery and action planning ability is possible in DCD, and they lend theoretical support to the use of new training techniques that focus on training motor imagery to improve motor skills in children with DCD.