Reduced motor imagery efficiency is associated with online control difficulties in children with probable developmental coordination disorder

Recent evidence indicates that the ability to correct reaching movements in response to unexpected target changes (i.e., online control) is reduced in children with developmental coordination disorder (DCD). Recent computational modeling of human reaching suggests that these inefficiencies may result from difficulties generating and/or monitoring internal representations of movement. This study was the first to test this putative relationship empirically. We did so by investigating the degree to which the capacity to correct reaching mid-flight could be predicted by motor imagery (MI) proficiency in a sample of children with probable DCD (pDCD). Thirty-four children aged 8 to 12 years (17 children with pDCD and 17 age-matched controls) completed the hand rotation task, a well-validated measure of MI, and a double-step reaching task (DSRT), a protocol commonly adopted to infer one's capacity for correcting reaching online. As per previous research, children with pDCD demonstrated inefficiencies in their ability to generate internal action representations and correct their reaching online, demonstrated by inefficient hand rotation performance and slower correction to the reach trajectory following unexpected target perturbation during the DSRT compared to age-matched controls. Critically, hierarchical moderating regression demonstrated that even after general reaching ability was controlled for, MI efficiency was a significant predictor of reaching correction efficiency, a relationship that was constant across groups. Ours is the first study to provide direct pilot evidence in support of the view that a decreased capacity for online control of reaching typical of DCD may be associated with inefficiencies generating and/or using internal representations of action.     

A review of five tests to identify motor coordination difficulties in young adults

Difficulties with low motor competence in childhood and adolescence, such as that seen in Developmental Coordination Disorder (DCD), often persist into adulthood. Identification of DCD at all ages is particularly challenging and problematic because of the diversity of motor symptoms. Many tests of motor proficiency and impairment have been developed for children up to 12 years of age. Whilst identification of DCD is important during childhood, it is of equal importance to identify and monitor the impact of this impairment as an individual grows and develops. Currently there is no test specifically designed to support diagnosis and monitor change in the age range 16–30 years. In this article we review five tests that have been used to assess motor competence among young adults (Bruininks–Oseretsky Test of Motor Proficiency-2, McCarron Assessment of Neuromuscular Development, Movement Assessment Battery for Children-2, Tufts Assessment of Motor Performance and the Zurich Neuromotor Assessment). Key issues relevant to testing motor skills in older populations, such as the inclusion of age appropriate skills, are explored. While the BOT-2 provided the most evidence for valid and reliable measurement of Criterion A of the diagnostic criteria for DCD among this age group, no test adequately evaluated Criterion B. Further evaluation of motor skill assessment among the young adult population is needed.     

Short-term motor learning of dynamic balance control in children with probable Developmental Coordination Disorder

PurposeTo explore the differences in learning a dynamic balance task between children with and without probable Developmental Coordination Disorder (p-DCD) from different cultural backgrounds.ParticipantsTwenty-eight Dutch children with DCD (p-DCD-NL), a similar group of 17 South African children (p-DCD-SA) and 21 Dutch typically developing children (TD-NL) participated in the study.MethodsAll children performed the Wii Fit protocol. The slope of the learning curve was used to estimate motor learning for each group. The protocol was repeated after six weeks. Level of motor skill was assessed with the Movement ABC-2.ResultsNo significant difference in motor learning rate was found between p-DCD-NL and p-DCD-SA, but the learning rate of children with p-DCD was slower than the learning rate of TD children. Speed–accuracy trade off, as a way to improve performance by slowing down in the beginning was only seen in the TD children, indicating that TD children and p-DCD children used different strategies. Retention of the level of learned control of the game after six weeks was found in all three groups after six weeks. The learning slope was associated with the level of balance skill for all children. This study provides evidence that children with p-DCD have limitations in motor learning on a complex balance task. In addition, the data do not support the contention that learning in DCD differs depending on cultural background.     

Deficits of visuospatial attention with reflexive orienting induced by eye-gazed cues in children with developmental coordination disorder in the lower extremities: An event-related potential study

The present study aims to investigate and compare the behavioral performance and event-related potentials (ERPs) measures in children with developmental coordination disorder (DCD) and typically developing (TD) children when performing the visuospatial attention task with reflexive orienting. Thirty children with DCD and 30 TD children were recruited and presented with central eye-gazed cues. The children needed to detect and respond to laterally presented reaction signals preceded by centrally presented non-predictive directional and non-directional eye-gazed cues, which directed them to attend covertly to the right or left field location, or straight ahead, via stepping on pedals with their bilateral lower limbs, while brain ERPs were concurrently recorded. The behavioral data showed that children with DCD responded slowly and exhibited a deficit in inhibitory control capacity as compared to TD children. In terms of electrophysiological characteristics, children with DCD showed distinct modulatory effects upon longer N2 and P3 latencies, smaller P3 amplitude, an elongated interval between N2 and the motor response (N2 latency-RT), and small areas on Contingent Negative Variation (CNV). The behavioral and ERP data suggest that children with DCD could have deficits in the ventral attention network and the mechanisms on the inhibitory control difficulty, when performing such a task, could be a slower response inhibitory process and stimulus classification speed, less ability in interhemispheric and cognitive-to-motor transfer speed, and less mature abilities with regard to anticipatorily executive and motor preparatory processes.     

Motor imagery training enhances motor skill in children with DCD: A replication study

BackgroundChildren with impaired motor coordination (or DCD) have difficulty using motor imagery. We have suggested that this difficulty is explained by the internal modeling deficit (IMD) hypothesis of DCD. Our previous training study lent support for this hypothesis by showing that a computerized imagery training protocol (involving action observation, and mental- and overt-rehearsal) was equally effective to perceptual-motor therapy (PMT) in promoting motor skill acquisition.AimsThe study presented here was designed to replicate and extend this finding, targeting a select group of children with moderate-to-severe DCD.Methods and ProceduresAll 36 children with DCD who participated were referred to the study and scored below the 10th percentile for their age on the Movement Assessment Battery for Children (MABC). Using a randomized control trial, the referred children were assigned randomly to one of three groups using a blocked procedure: imagery training, perceptual-motor training (PMT), and wait-list control. Motor proficiency was measured using the MABC, pre and post-training. Individual training consisted of 60-min sessions, conducted once a week for 5 weeks.ResultsResults showed that the imagery protocol was equally effective as PMT in promoting motor skill acquisition, with moderate-to-large effect sizes. Individual differences showed that the majority of children in the two intervention groups improved their motor performance significantly.ConclusionsOverall, these results further support the use of motor imagery protocols in the treatment of DCD, and tentative support for the IMD hypothesis. Developmental and dose issues in the implementation of imagery-based intervention are discussed.     

Mild impairments of motor imagery skills in children with DCD

It has been hypothesized that the underlying mechanism of clumsy motor behaviour in children with Developmental Coordination Disorder (DCD) is caused by a deficit in the internal modelling for motor control. An internal modelling deficit can be shown on a behavioural level by a task that requires motor imagery. Motor imagery skills are suggested to be related to anticipatory action planning, but motor imagery and action planning have not been tested within the same child. In the present study, action planning and motor imagery skills were assessed in 82 children between 7 and 12 years of age. Twenty-one of these children met the criteria for DCD, which was assessed by the McCarron Assessment of Neuromuscular Development and 56 of these children were used in the control group. Motor imagery was tested by a mental rotation task of hands that were shown from a back and palm point of view. The results show that motor imagery is affected in children with DCD but only in conditions with complex task constraints (i.e., rotation of hand stimuli presented in palm view). These results provide partial support for the internal modelling deficit hypothesis. We were not able to elicit motor planning deficits in this group, however, and argue that more complex planning tasks may be needed to identify such deficits.     

The effectiveness of exercise intervention on inhibitory control in children with developmental coordination disorder: Using a visuospatial attention paradigm as a model

Children with developmental coordination disorder (DCD) have been demonstrated to show a deficit of inhibitory control in volitional shifts of attention. The aim of this study was to use ecological intervention to investigate the efficacy of table-tennis training on treating both problems with attentional networks and motor disorder in children with DCD. Forty-three children aged 9–10 years old were screened using the Movement Assessment Battery for Children and divided into DCD (n = 27) and typically developing (TD, n = 16) groups. Children with DCD were then quasi-randomly assigned to either a DCD-training group who underwent a ten-week table-tennis training program with a frequency of 3 times a week or a DCD non-training group. Before and after training, the capacity of inhibitory control was examined with the endogenous Posner paradigm task for DCD and TD groups. Table-tennis training resulted in significant improvement of cognitive and motor functions for the children with DCD. The study demonstrated that exercise intervention employed within the school setting can benefit the inhibitory control and motor performance in children with DCD. However, future research efforts should continue to clarify whether the performance gains could be maintained over time.     

The effect of motor load on planning and inhibition in developmental coordination disorder

Previous research has reported mixed findings regarding executive function (EF) abilities in developmental coordination disorder (DCD), which is diagnosed on the basis of significant impairments in motor skills. The current study aimed to assess whether these differences in study outcomes could result from the relative motor loads of the tasks used to assess EF in DCD. Children with DCD had significant difficulties on measures of inhibition and planning compared to a control group, although there were no significant correlations between motor skills and EF task performance in either group. The complexity of the response, as well as the component skills required in EF tasks, should be considered in future research to ensure easier comparison across studies and a better understanding of EF in DCD over development.     

Toward a motor signature in autism: Studies from human-machine interaction

BackgroundAutism spectrum disorder (ASD) is a heterogeneous group of neurodevelopmental disorders which core symptoms are impairments in socio-communication and repetitive symptoms and stereotypies. Although not cardinal symptoms per se, motor impairments are fundamental aspects of ASD. These impairments are associated with postural and motor control disabilities that we investigated using computational modeling and developmental robotics through human-machine interaction paradigms.MethodFirst, in a set of studies involving a human–robot posture imitation, we explored the impact of 3 different groups of partners (including a group of children with ASD) on robot learning by imitation. Second, using an ecological task, i.e. a real-time motor imitation with a tightrope walker (TW) avatar, we investigated interpersonal synchronization, motor coordination and motor control during the task in children with ASD (n = 29), TD children (n = 39) and children with developmental coordination disorder (n = 17, DCD).ResultsFrom the human–robot experiments, we evidenced that motor signature at both groups’ and individuals’ levels had a key influence on imitation learning, posture recognition and identity recognition. From the more dynamic motor imitation paradigm with a TW avatar, we found that interpersonal synchronization, motor coordination and motor control were more impaired in children with ASD compared to both TD children and children with DCD. Taken together these results confirm the motor peculiarities of children with ASD despite imitation tasks were adequately performed.DiscussionStudies from human-machine interaction support the idea of a behavioral signature in children with ASD. However, several issues need to be addressed. Is this behavioral signature motoric in essence? Is it possible to ascertain that these peculiarities occur during all motor tasks (e.g. posture, voluntary movement)? Could this motor signature be considered as specific to autism, notably in comparison to DCD that also display poor motor coordination skills? We suggest that more work comparing the two conditions should be implemented, including analysis of kinematics and movement smoothness with sufficient measurement quality to allow spectral analysis.     

Head–torso–hand coordination in children with and without developmental coordination disorder

Aim This study investigated the nature of coordination and control problems in children with developmental coordination disorder (DCD). Method Seven adults (two males, five females, age range 20–28y; mean 23y, SD 2y 8mo) and eight children with DCD (six males, two females, age range 7–9y; mean 8y, SD 8mo), and 10 without DCD (seven males, three females, age range 7–9y; mean 8y, SD 7mo) sat in a swivel chair and looked at or pointed to targets. Optoelectronic apparatus recorded head, torso, and hand movements, and the spatial and temporal characteristics of the movements were computed. Results Head movement times were longer (p<0.05) in children with DCD than in the comparison group, even in the looking task, suggesting that these children experience problems at the lowest level of coordination (the coupling of synergistic muscle groups within a single degree of freedom). Increasing the task demands with the pointing condition affected the performance of children with DCD to a much greater extent than the other groups, most noticeably in key feedforward kinematic landmarks. Temporal coordination data indicated that all three groups attempted to produce similar movement patterns to each other, but that the children with DCD were much less successful than age‐matched children in the comparison group. Interpretation Children with DCD have difficulty coordinating and controlling single degree‐of‐freedom movements; this problem makes more complex tasks disproportionately difficult for them. Quantitative analysis of kinematics provides key insights into the nature of the problems faced by children with DCD.     

Neurobiological bases and neurophysiological correlates of developmental coordination disorders

Among psychomotor disorders in children, developmental coordination disorder (DCD) is characterized by a motor skill impairment that interferes with psychomotor development, academic performance and activities of daily living, despite normal intelligence. The main behavioural phenomena (lack of postural control, coordination and motor learning) suggest involvement of cerebellum, basal ganglia and frontal and parietal lobes. Our studies on a synchronisation/syncopation task, with EEG recording (coherence analysis and evoked potential), show that DCD children (8 to 12 years old) exhibit major interindividual variability and do not improve performance with repetition. In younger DCD children, an increase of coherence between fronto-central regions was reported, and, for evoked potential, an increase of motor preparation component and a N100 latency longer than control children. These findings support the idea of a general synchronization disorder in DCD children and furnish elements allowing a better understanding of intra- and interindividual variability.     

Bimanual coordination and aging: Neurobehavioral implications

We investigate whether aging leads to global declines in discrete and continuous bimanual coordination tasks thought to rely on different control mechanisms for temporal coupling of the limbs. All conditions of continuous bimanual circle drawing were associated with age-equivalent temporal control. This was also true for discrete simultaneous tapping. Older adults’ between-hand coordination deficits were specific to discrete tapping conditions requiring asynchronous intermanual timing and were associated with self-reported executive dysfunction on the Dysexecutive (DEX) questionnaire. Also, older adults exclusively showed a relationship between the most difficult bimanual circling condition and a measure of working memory. Thus, age-related changes in bimanual coordination are specific to task conditions that place complex timing demands on left and right hand movements and are, therefore, likely to require executive control.     

Intact procedural motor sequence learning in developmental coordination disorder

The purpose of the present study was to explore the possibility of a procedural learning deficit among children with developmental coordination disorder (DCD). We tested 34 children aged 6–12 years with and without DCD using the serial reaction time task, in which the standard keyboard was replaced by a touch screen in order to minimize the impact of perceptuomotor coordination difficulties that characterize this disorder. The results showed that children with DCD succeed as well as control children at the procedural sequence learning task. These findings challenge the hypothesis that a procedural learning impairment underlies the difficulties of DCD children in acquiring and automatizing daily activities. We suggest that the previously reported impairment of children with DCD on the serial reaction time task is not due to a sequence learning deficit per se, but rather due to methodological factors such as the response mode used in these studies.     

Deficits in the covert orienting of attention in children with Developmental Coordination Disorder: Does severity of DCD count?

Children with Developmental Coordination Disorder (DCD) show deficits in the covert orienting of visuospatial attention, suggesting an underlying issue in attentional disengagement and/or inhibitory control. However, an important theoretical issue that remains unclear is whether the pattern of deficits varies with DCD severity. Fifty-one children with moderate DCD (MDCD), 24 children with severe DCD (SDCD), and 38 typically developing (TD) children participated in the study. Their performance was compared on the covert orienting of visuospatial attention task (COVAT), specifically the voluntary control mode. Results showed that the pattern of performance differed between groups. At a short stimulus-response asynchrony (350 ms), the difference in response times for validly and invalidly cued trials was similar for all three groups. However, at the longer SOA (800 ms), both DCD groups continued to show a relative disadvantage for responses that followed invalid cues. This suggests that a deficit in response inhibition and/or attentional disengagement is manifest in children with both moderate and severe DCD. The implications of these findings for theory and treatment are discussed.     

Postural responses to a suprapostural visual task among children with and without developmental coordination disorder

We sought to determine the effects of varying the perceptual demands of a suprapostural visual task on the postural activity of children with developmental coordination disorder (DCD), and typically developing children (TDC). Sixty-four (32 per group) children aged between 9 and 10 years participated. In a within-participants design, each child performed a signal detection task at two levels of difficulty, low (LD) and high difficulty (HD). During performance of the signal detection tasks we recorded positional variability of the head and torso using a magnetic tracking system. We found that task difficulty had a greater effect on task performance among the TDC group than among children with DCD. Overall positional variability was greater the DCD group than in the TDC group. In the TDC group, positional variability was reduced during performance of the HD task, relative to sway during performance of the LD task. In the DCD group, positional variability was greater during performance of the HD task than during performance of the LD task. In children, DCD may reduce the strength of functional integration of postural activity with the demands of suprapostural visual tasks.     

A dyspraxic deficit in specific language impairment and developmental coordination disorder? Evidence from hand and arm movements

The extent to which children with either specific language impairment (SLI) or developmental coordination disorder (DCD) could be considered dyspraxic was examined using three tasks involving either familiar, or unfamiliar actions. SLI is diagnosed in children who fail to develop language in the normal fashion for no apparent reason, while the DCD diagnosis is applied to a child who experiences problems with movement in the absence of other difficulties. Seventy-two children aged between 5 and 13 years participated, falling into one of four groups: (1) children with specific language impairment (SLI), (2) children with developmental coordination disorder (DCD), (3) age-matched control children, and (4) younger control children. The performance of the clinical groups resembled that of younger normally developing children. Children with SLI, DCD, and the younger controls showed significant difficulty on the task requiring the production of familiar, but not unfamiliar postures. The deficit observed in the SLI group is particularly striking because it was seen both in those with and those without recognized motor difficulties.     

发育性协调运动障碍儿童执行功能的横断面研究(英文)

背景发育性协调运动障碍(developmental coordination disorder,DCD)患儿存在明显的运动能力、学习和日常生活能力的下降。国外研究表明,患儿的这些能力下降与其认知功能尤其是执行功能的受损有关,但国内尚无此类研究来证实这些结果。目的比较发育性协调运动障碍患儿与正常儿童的执行功能。方法对2008年3月至2010年3月在杭州市第七人民医院就诊并符合DSM-IV发育性协调运动障碍诊断的39例患儿采用威斯康星卡片分类测验(Wisconsin Card Sorting Test,WCST)进行评估。另外,在杭州某小学随机抽取39名健康儿童作为对照组,同样对他们进行WCST评估。结果两组在WCST的总应答数及非持续错误数相似,但是研究组的错误应答数、持续性应答数和持续性错误数均显著高于对照组。另外,研究组患儿完成分类数低于对照组,完成第一个分类所需的应答数也高于对照组。结论本研究证实了先前一些研究的结果,即发育性协调运动障碍患儿存在明显的执行功能缺陷。所有这些研究均提示,患儿的执行功能缺陷显著影响了其智能和社会功能的发展。     

Association between visual perceptual deficits and motor deficits in children with developmental coordination disorder

This study explored the relation between a motor-free visual perceptual deficit, different visual-motor integration deficits, and different motor skills in children with developmental coordination disorder (DCD). Thirty-six children (22 males), aged 9 or 10 years, with DCD and a control group (n=36), matched for age and sex, were assessed with the Movement Assessment Battery for Children (MABC), a ball-catching test, a jumping test, a timed response task to a visual moving stimulus, and the Beery-Buktenica Developmental Test of Visual-Motor Integration, incorporating copying, visual discrimination, and tracing tasks. Children with DCD performed significantly worse than the control group on all measures. The visual discrimination task did not correlate significantly with any of the motor tasks. The visual timing task correlated significantly with the ball-catching test in the DCD group. The copying test was significantly correlated with the MABC in the DCD group. The association between visual-perceptual deficits and motor tasks was shown to be task specific.     

Working memory, processing speed, and set-shifting in children with developmental coordination disorder and attention-deficit-hyperactivity disorder

It has been suggested that the high levels of comorbidity between attention-deficit-hyperactivity disorder (ADHD) and developmental coordination disorder (DCD) may be attributed to a common underlying neurocognitive mechanism. This study assessed whether children with DCD and ADHD share deficits on tasks measuring working memory, set-shifting, and processing speed. A total of 195 children aged between 6 years 6 months and 14 years 1 month (mean 10y 4mo [SD 2y 2mo]) were included in this study. A control group (59 males, 79 females), a DCD group (12 males, six females), an ADHD-predominantly inattentive group (16 males, four females), and an ADHD-combined group (15 males, four females), were tested on three executive functioning tasks. Children with DCD were significantly slower on all tasks, supporting past evidence of a timing deficit in these children. With few exceptions, children with ADHD did not perform more poorly than control children. These findings demonstrate the importance of identifying children with motor deficits when examining tasks involving a timing component.     

A reaching test reveals weak hand preference in specific language impairment and developmental co-ordination disorder

A reaching test for quantifying hand preference (QHP task) was given to 7- to 11- year-old children with specific language impairment (SLI) or developmental coordination disorder (DCD). The performance of these clinical children was compared to both an age-matched and younger control group. The four groups did not differ in terms of preferred writing hand or preference on a handedness questionnaire. The QHP measure discriminated the clinical and younger control groups from the age-matched controls, but not from each other. Right-handed children with SLI, DCD, and the younger controls reached predominantly with the right hand to spatial positions located to the right of their body's midline and with the left hand to positions situated to its left. Right-handers in the age-matched control group showed a significantly greater tendency to use their right hand to reach to all spatial positions. The increased tendency of the children with SLI to use the non-preferred hand was particularly striking because it was seen both in those with and without recognised motor difficulties. The QHP task appears to be a sensitive, but non-specific, indicator of developmental disorders.