Dysfunction of the attentional brain network in children with Developmental Coordination Disorder: a fMRI study

Use of Virtual Reality in School-Aged Children with Developmental Coordination Disorder: A Novel Approach

Virtual reality (VR) applications in paediatric rehabilitation are recent but promising. This brief report describes a VR rehabilitation program for a small sample of children with Developmental Coordination Disorder (DCD). The program focused explicitly on executive functions, a key area of concern for this population. It was conducted over 11 weeks in the CARE Lab. This lab was designed with appropriate structural characteristics and sophisticated technology to provide a rehabilitative setting with recreational and semi-immersive features. Before and after the VR training, the children were evaluated in terms of visual attention, inhibition, planning abilities, and visual-motor coordination. The rehabilitation programs were customised according to the clinical needs and the functional profile of each patient, proposing different games with variable complexity levels. These preliminary results showed a global and clinically significant change in executive functions, especially visual attention and inhibition skills. These findings suggest interesting implications for clinical practice, providing new information for professionals regarding the application of VR in the field of paediatric rehabilitation.

Association between Motor Skills, Occupational Performance, and Mental Health in Japanese Children with Neurodevelopmental Disorders: A Cross-Sectional Correlational Study

BACKGROUND

Motor skills have been linked to executive functions (EFs) in children with developmental coordination disorder (DCD). However, the traits of other neurodevelopmental disorders (NDDs), such as attention-deficit/hyperactivity disorder and autism spectrum disorder, remain overlooked. Therefore, this study explored the association between motor skills, occupational performance, and mental health in older kindergarten children with DCD and other NDDs. Overall, 95 participants aged 5-6 years were included in this study and divided into four groups: DCD traits (DCD-t), DCD-t + NDD traits (DCD-t + NDD-t), NDD-t-only, and typically developing children. Motor skills, EFs, and mental health were assessed using the DCD Questionnaire (DCDQ-J) and Movement Assessment Battery for Children-Second Edition, School Assessment of Motor and Process Skills (S-AMPS), and the Strengths and Difficulties Questionnaire (SDQ), respectively. The DCD-t + NDD-t group exhibited a strong correlation between the S-AMPS motor skill score and the DCDQ-J fine motor skill score (r = 0.88, p < 0.001) and between the total DCDQ-J score and the SDQ Total Difficulties Score (r = -0.94, p < 0.001). The findings indicate that children with DCD-t and NDD-t are more likely to experience EF and mental health problems than those with DCD-t only.

Study protocol to examine the effects of acute exercise on motor learning and brain activity in children with developmental coordination disorder (ExLe-Brain-DCD)

INTRODUCTION

Developmental coordination disorder (DCD) is one of the most prevalent pediatric chronic conditions. Without proper intervention, significant delays in motor skill performance and learning may persist until adulthood. Moderate-to-vigorous physical exercise has been proven to improve motor learning (adaptation and consolidation) in children with or without disorders. However, the effect of a short bout of physical exercise on motor adaptation and consolidation in children with DCD has not been examined. Furthermore, the role of perceptual-motor integration and attention as mediators of learning has not been examined via neuroimaging in this population.

OBJECTIVES

Therefore, the primary aims of this project will be to compare children with and without DCD to (a) examine the effect of acute exercise on motor learning (adaptation and consolidation) while performing a rotational visuo-motor adaptation task (rVMA), and (b) explore cortical activation in the dorsolateral- and ventrolateral-prefrontal cortex areas while learning the rVMA task under rest or post-exercise conditions.

METHODS

One hundred twenty children will be recruited (60 DCD, 60 controls) and within-cohort randomly assigned to either exercise (13-minute shuttle run task) or rest prior to performing the rVMA task. Adaptation and consolidation will be evaluated via two error variables and three retention tests (1h, 24h and 7 days post adaptation). Cortical activation will be registered via functional near-infrared spectroscopy (fNIRS) during the baseline, adaptation, and consolidation.

DISCUSSION

We expect to find exercise benefits on motor learning and attention so that children with DCD profiles will be closer to those of children with typical development. The results of this project will provide further evidence to: (a) better characterize children with DCD for the design of educational materials, and (b) establish acute exercise as a potential intervention to improve motor learning and attention.

Effect of verbal cues on the coupling and stability of anti-phase bimanual coordination pattern in children with probable developmental coordination disorder

The study of the emergence and stability of bimanual and interlimb coordination patterns in children with Developmental Coordination Disorder (DCD) has shown that they encounter greater difficulties in coupling their limbs compared to typically developing (TD) children. Verbal cues have been identified as strategies to direct children's attention to more relevant task information, thus potentially improving motor performance. Consequently, this study investigated the effect of providing verbal cues on the execution of bimanual tasks in children with and without probable DCD. Twenty-eight children aged 9-10, matched by age and gender, were divided into two groups: pDCD [n = 14] and TD. The children performed bilateral trajectory movements with both hands (horizontal back-and-forth), holding a pen on a tablet, in anti-phase (180°) coordination pattern, in two conditions: No cues and Verbal cues. In the last condition, children received verbal cues to maintain the anti-phase pattern even with an increase in hand oscillation frequency. Relative phase and variability of relative phase between the hands were calculated for analysis of pattern coupling and stability. Hand cycles, movement amplitude, and tablet pressure force were calculated to analyze pattern control parameters. All these variables were compared between groups and conditions. The results indicated that despite the pDCD group showing greater variability in the anti-phase coordination pattern compared to the TD group, both groups performed better in the Verbal cues than the No cues condition. Furthermore, the pDCD group exhibited more hand movement cycles and applied greater pressure force compared to the TD group, suggesting different motor control strategies during the bimanual task. It is suggested that the use of verbal cues during bimanual task execution improves children's performance, potentially by promoting interaction between attention, as a cognitive function, and intrinsic coordination dynamics, thereby reducing variability in the perceptual-motor system.

Possible disrupted biological movement processing in Developmental Coordination Disorder

AIM

There is emerging evidence that the Mirror Neuron System (MNS) might contribute to the motor learning difficulties characteristic of Developmental Coordination Disorder (DCD). This study aimed to identify whether MNS activity differed between children with and without DCD during action observation, action execution and during a non-action baseline.

METHODS

Electroencephalography (EEG) was used to measure mu rhythm (a proxy for MNS activation) in 8-12-year-old children either with (n = 20) or without (n = 19) a diagnosis of DCD. The mu rhythm was recorded at rest and during five experimental conditions: (1) observation of gross motor and (2) fine motor actions; (3) execution of gross motor and (4) fine motor actions; and (5) non-biological movement. To address whether potential co-occurring traits of other neurodevelopmental conditions were associated with differences in mu rhythm, parents reported their child's attention and social communication skills. Mixed and repeated measure ANOVAs were conducted to examine differences in mu desynchronization and mu power respectively.

RESULTS

The non-DCD group showed greater mu rhythm desynchronization than children with DCD (i.e., more MNS activity), with both groups demonstrating increasing desynchronization from observation of fine actions to execution of gross actions. However, we also found that the children with DCD had less mu power during the non-biological movement condition than the non-DCD children, although mu power did not differ between groups during the resting condition. Correlations between mu desynchronization and children's attention and motor skills showed that poorer attention and motor abilities were associated with reduced MNS activity.

CONCLUSION

Compared to children without DCD, the MNS in children with DCD did not distinguish between biological and non-biological movement. It is possible that the reduced specificity of the MNS in children with DCD is an underlying factor in the motor impairments observed in the disorder. The differential MNS activity could reflect broader atypical activity in perceptual networks that feed into the MNS in DCD.

Atypical procedural learning skills in children with Developmental Coordination Disorder

We investigated the procedural learning deficit hypothesis in Developmental Coordination Disorder (DCD) while controlling for global performance such as slower reaction times (RTs) and variability. Procedural (sequence) learning was assessed in 31 children with DCD and 31 age-matched typically developing (TD) children through a serial reaction time task (SRTT). Sequential and random trial conditions were intermixed within five training epochs. Two repeated measures ANOVAs were conducted on a Sequence-Specific Learning Index (SSLI) and a Global Performance Index (GPI, speed/accuracy measure) with Epoch (for SSLI and GPI) and Condition (for GPI) as within-subjects factors, and Group as between-subjects factor. Controlling for RTs differences through normalized RTs, revealed a global reduction of SSLI in children with DCD compared with TD peers suggesting reduced sequence learning skills in DCD. Still, a significant Group x Condition interaction observed on GPI indicated that children from both groups were able to discriminate between sequential and random trials. DCD presented reduced procedural learning skills after controlling for global performance. This finding highlights the importance of considering the general functioning of the child while assessing learning skills in patients.

Motor learning in developmental coordination disorder: behavioral and neuroimaging study

Developmental coordination disorder (DCD) is characterized by motor learning deficits that are poorly understood within whole-body activities context. Here we present results of one of the largest non-randomized interventional trials combining brain imaging and motion capture techniques to examine motor skill acquisition and its underpinning mechanisms in adolescents with and without DCD. A total of 86 adolescents with low fitness levels (including 48 with DCD) were trained on a novel stepping task for a duration of 7 weeks. Motor performance during the stepping task was assessed under single and dual-task conditions. Concurrent cortical activation in the prefrontal cortex (PFC) was measured using functional near-infrared spectroscopy (fNIRS). Additionally, structural and functional magnetic resonance imaging (MRI) was conducted during a similar stepping task at the beginning of the trial. The results indicate that adolescents with DCD performed similarly to their peers with lower levels of fitness in the novel stepping task and demonstrated the ability to learn and improve motor performance. Both groups showed significant improvements in both tasks and under single- and dual-task conditions at post-intervention and follow-up compared to baseline. While both groups initially made more errors in the Stroop task under dual-task conditions, at follow-up, a significant difference between single- and dual-task conditions was observed only in the DCD group. Notably, differences in prefrontal activation patterns between the groups emerged at different time points and task conditions. Adolescents with DCD exhibited distinct prefrontal activation responses during the learning and performance of a motor task, particularly when complexity was increased by concurrent cognitive tasks. Furthermore, a relationship was observed between MRI brain structure and function measures and initial performance in the novel stepping task. Overall, these findings suggest that strategies that address task and environmental complexities, while simultaneously enhancing brain activity through a range of tasks, offer opportunities to increase the participation of adolescents with low fitness in physical activity and sports.

Perspective: Acknowledging complexity to advance the understanding of developmental coordination disorder

Developmental Coordination Disorder (DCD) is a heterogeneous neurodevelopmental disorder known for primary symptoms of motor learning and execution difficulties. Recent research has consistently suggested DCD symptoms span broadly beyond motor difficulties, yet a majority of research and practice approaches the investigation, diagnosis, and treatment of DCD with a reductionist framework. Therefore, this paper suggests the paradigm of complexity theory as a means for better conceptualization, assessment, and treatment of DCD. First, the perspective of complexity theory and its relevance to DCD is described. Then, examples from recent research which attempt to acknowledge and capture the complex nature of DCD are highlighted. Finally, suggestions for considering and measuring complexity of DCD in future research and practice are provided. Overall, the perspective of complexity can propel the research forward and improve the understanding of DCD relevant to assessment and treatment. The complexity paradigm is highly relevant to describing the evolving and multidimensional picture of DCD, understanding heterogeneous symptom profiles, making connections to interconnected secondary symptoms, and beyond.

Does the Degree and/or Direction of Handedness in Children With Developmental Coordination Disorder Influence Motor and Cognitive Performance? A Pilot Study

Research has shown that nonright-handedness in children with developmental coordination disorder (DCD) is associated with poorer motor and cognitive performance. This study investigated the influence of degree and direction of handedness on performance using the Home Handedness Questionnaire, the Hit-the-Dot test, the Movement Assessment Battery for Children, and the digital Trail-Making Test. Eighteen children with DCD and 21 typically developing children aged 8–12 years participated in this study. The distribution of degree and direction of handedness in the group of DCD children were not different from that found in the typically developing group. In the Hit-the-Dot test, typically developing children significantly performed better than children with DCD, no matter which hand was dominant or to which degree. A significant inconsistent-handed advantage in the subdomain balance was found for children with DCD. Inconsistent handedness also seems to be an advantage for children with DCD on the digital Trail-Making Test performance. The relationship between the subcategories of the Movement Assessment Battery for Children and the digital Trail-Making Test part B is stronger for consistent than for inconsistent handedness. Our findings suggest that children with DCD and inconsistent handedness might benefit from greater crosstalk across hemispheres. In addition, these predispositions can be reinforced or discouraged throughout development and via occupational therapy.

Modulation effects of the intact motor skills on the relationship between social skills and motion perceptions in children with autism spectrum disorder: A pilot study

BACKGROUND

An individual with autism spectrum disorder (ASD) has social skill, motor skill, and motion perception deficits. However, the relationship among them was not clarified. Therefore, this study aimed to evaluate the effects of motor skills on social skills and motion perception.

METHODS

Five typically developed children and fourteen children with ASD participated in our study. The N200 component, a brain activity indicating motion perception, was induced in mid-temporal (MT/V5) brain area by watching a random dot kinematograph, and was recorded using a scalp electroencephalogram. Furthermore, the social responsiveness scale (SRS) indicating the social skill deficit, the developmental coordination disorder questionnaire (DCDQ) estimating the developmental coordination disorder (DCD), and the movement assessment battery for children second edition (MABC-2) indicating motor skills were recorded in the children with ASD. A hierarchical multiple regression analysis was conducted to examine the modulation effects of motor skills on the relationship between social skills and motion perception. The dependent variable was the N200 latency, and the independent variables were SRS, MABC-2, and combined MABC-2 and SRS.

RESULTS

The N200 latency was more delayed in children with ASD relative that in typically developed children. Intact balance ability modulated the relationship between social skills and N200 latency in children with ASD. Within the high balance ability, when the social skills worsened, the N200 latency was shortened.

CONCLUSIONS

This is the first report that intact motor skills could modulate the relationship between social skills and motion perception.

The adult developmental coordination disorders/dyspraxia checklist - German: adapted factor structure for the differentiation of DCD and ADHD

BACKGROUND

The Adult Dyspraxia/DCD Checklist (ADC) is the only existing self-report questionnaire to screen adults for potential Developmental Coordination Disorder (DCD). It was developed in English and Hebrew, however, its factor structure has not yet been assessed.

AIMS

The goals of the current study were to (1) develop and refine a German translation, (2) explore the emerging factors in a new and restructured ADC in German and apply this structure to an English ADC, and (3) explore its potential for distinguishing DCD versus ADHD.

METHOD

In a series of three studies, we assessed comprehensibility of the translation and revisions to the questionnaire. We further examined subscale structure in a sample of N = 148 individuals with DCD or ADHD and retested it in an English-speaking sample (N = 134).

RESULTS

Overall, we found decent reliability and construct validity for the German ADC. Three components emerged with themes of fine motor coordination, gross motor coordination, and executive functions which had strong psychometric properties in German and English.

CONCLUSIONS

The studies collectively highlight the German translation is effective and has strong potential to differentiate DCD and ADHD. Most notably, there are unique symptom profiles in motor and executive functioning difficulties in adults with DCD or ADHD. WHAT THIS PAPER ADDS?: The translation and preliminary validation of the German ADC in this study has the potential to screen for probable DCD in German-speaking adults for the first time. In addition, the new subscale structure can be generalized to the English version as well and allows for the potential assessment of several key symptomatic patterns in the realms of gross motor, fine motor, and executive functioning skills that differ between adults with DCD and ADHD. These differences were fairly consistent between English- and German-speaking samples, indicating potential for more widespread assessment and differentiation of DCD and ADHD.

Developmental Coordination Disorder: State of the Art and Future Directions from a Neurophysiological Perspective

Developmental coordination disorder (DCD) is a common neurodevelopmental condition characterized by disabling motor impairments being visible from the first years of life. Over recent decades, research in this field has gained important results, showing alterations in several processes involved in the regulation of motor behavior (e.g., planning and monitoring of actions, motor learning, action imitation). However, these studies mostly pursued a behavioral approach, leaving relevant questions open concerning the neural correlates of this condition. In this narrative review, we first survey the literature on motor control and sensorimotor impairments in DCD. Then, we illustrate the contributions to the field that may be achieved using transcranial magnetic stimulation (TMS) of the motor cortex. While still rarely employed in DCD research, this approach offers several opportunities, ranging from the clarification of low-level cortical electrophysiology to the assessment of the motor commands transmitted throughout the corticospinal system. We propose that TMS may help to investigate the neural correlates of motor impairments reported in behavioral studies, thus guiding DCD research toward a brain-oriented acknowledgment of this condition. This effort would help translational research to provide novel diagnostic and therapeutic tools.

Fine motor skill automatization and working memory in children with and without potential fine motor impairments: An explorative study

AIMS

The present study explored fine motor skill automatization and working memory in kindergarten children with and without potential fine motor impairments. For both groups, lower performance was expected in a cognitive-motor dual-task compared to single-tasks. Children with potential fine motor impairments were expected to show higher dual-task costs (indicating lower automatization) and lower working memory performance compared to children without potential fine motor impairments.

METHODS

The sample included 18 kindergarten children (mean age M = 67.17 months, SD = 4.34 months) with potential fine motor impairments (scoring at or below the 9th percentile of the manual dexterity scale of the Movement ABC-2; Petermann, 2011) and 36 children scoring above the 9th percentile of the manual dexterity scale of the Movement ABC-2 (mean age M = 67.56 months; SD = 3.74). All children completed a fine motor task (trail drawing) and a working memory task (digit span backwards) in single- and dual-task conditions.

RESULTS

Results showed an overall lower cognitive but not fine motor performance in the dual-task condition compared to the single-task condition. Overall, the group scoring above the 9th percentile showed a lower error-to-length ratio and higher working memory performance than the group with potential fine motor impairments. The dual-task costs did not differ between the groups.

CONCLUSIONS

Although the potential fine motor impaired children did not show an automatization deficit, they might be at risk of academic problems due to their lower fine motor and working memory performance. Implications for school and interventions are discussed.

Brain functional connectivity in children with developmental coordination disorder following rehabilitation intervention

BACKGROUND

Children with developmental coordination disorder (DCD) show improved motor function after Cognitive Orientation to Occupational Performance (CO-OP) intervention; however, the neural basis for these improvements is unknown.

METHODS

In this randomized waitlist-controlled trial, 78 children with DCD (with/without ADHD) were randomly assigned to either a treatment or waitlist group and underwent three resting-state MRI scans over six months. The treatment group received intervention between the first and second scan; the waitlist group received intervention between the second and third scan.

RESULTS

After CO-OP intervention, children with DCD [13 male, 8 female; mean (SD) age: 10.0 (1.7) years] showed increased functional connectivity between the default mode network and right anterior cingulate gyrus (p < 0.01). Additional gains were noted at follow-up three months after the intervention, with greater functional connectivity between the dorsal attention network and precentral gyrus (p < 0.02). However, children with DCD + ADHD [18 male, 1 female; mean (SD) age: 10.0 (1.14) years] did not show brain changes following CO-OP.

CONCLUSION

For children with DCD, increased functional connectivity in networks associated with self-, emotion-, and attention-regulation may underlie motor skill improvements observed after CO-OP intervention. Modifications to the CO-OP protocol may be required to induce similar brain changes in children with DCD + ADHD.

IMPACT

This study provides neuroscientific evidence for the Cognitive Orientation to Occupational Performance (CO-OP) approach as an effective rehabilitation intervention to induce brain and behavioral changes in children with DCD. While children with DCD ± ADHD showed improved motor function after CO-OP, only children with DCD showed brain changes after intervention. Children with DCD showed increased functional connectivity in networks associated with self-, emotion-, and attention-regulation after the intervention. Treatment modifications may be required to induce similar brain changes in children with DCD + ADHD. Pediatricians are encouraged to refer children with DCD  with and without ADHD for CO-OP intervention to improve their motor skills.

Early Motor Milestones in Infancy and Later Motor Impairments: A Population-Based Data Linkage Study

BACKGROUND

Developmental Coordination Disorder (DCD) is a neurodevelopmental condition with high prevalence. Early motor milestones are important markers to identify DCD. The current study aims to evaluate the association between the onset of crawling and independent walking and their transition pattern during infancy and later motor impairments.

METHODS

A total of 8,395 children aged 3-6 years old in China were included in the final analysis. A parent questionnaire was used to collect early milestone onset data. Children's motor performance was measured using the Movement Assessment Battery for Children-2nd edition (MABC-2). The association between motor milestones and motor impairment was analyzed using a multilevel regression model.

RESULTS

The result showed that a 1-month delay in crawling onset increased the risk of significant overall motor impairment by 5.3, and 14.0% when adjusting for child and family characteristics. A 1-month delay in walking onset increased the risk of significant overall motor, fine, gross, and balance impairment by 21.7, 8.3, 13.3, and 17.8%. A 1 month increase in the transition time from crawling to independent walking increased the risk of significant overall motor and gross motor impairment by 7.7 and 6.6%. These results were inconsistent across different age bands (each p < 0.05).

CONCLUSIONS

Our study indicates that even a mild delay in crawling and walking onsets in infancy increase the risk for subsequent motor impairments in childhood, and children with motor impairments revealed a different transition pattern from crawling to walking. The motor abilities of children with motor impairments can be observed to diverge from typically developing children as early as 6-8 months old. The findings can facilitate the early identification of motor impairments in children, and provide early signs to initiate intervention.

Atypical resting-state functional brain connectivity in children with developmental coordination disorder

Children with developmental coordination disorder (DCD) present lower abilities to acquire and execute coordinated motor skills. DCD is frequently associated with visual perceptual (with or without motor component) impairments. This magnetoencephalography (MEG) study compares the brain resting-state functional connectivity (rsFC) and spectral power of children with and without DCD. 29 children with DCD and 28 typically developing (TD) peers underwent 2 × 5 min of resting-state MEG. Band-limited power envelope correlation and spectral power were compared between groups using a functional connectome of 59 nodes from eight resting-state networks. Correlation coefficients were calculated between fine and gross motor activity, visual perceptual and visuomotor abilities measures on the one hand, and brain rsFC and spectral power on the other hand. Nonparametric statistics were used. Significantly higher rsFC between nodes of the visual, attentional, frontoparietal, default-mode and cerebellar networks was observed in the alpha (maximum statistics, p = .0012) and the low beta (p = .0002) bands in children with DCD compared to TD peers. Lower visuomotor performance (copying figures) was associated with stronger interhemispheric rsFC within sensorimotor areas and power in the cerebellum (right lobule VIII). Children with DCD showed increased rsFC mainly in the dorsal extrastriate visual brain system and the cerebellum. However, this increase was not associated with their coordinated motor/visual perceptual abilities. This enhanced functional brain connectivity could thus reflect a characteristic brain trait of children with DCD compared to their TD peers. Moreover, an interhemispheric compensatory process might be at play to perform visuomotor task within the normative range.

Subcortical brain structure in children with developmental coordination disorder: A T1-weighted volumetric study

Developmental coordination disorder (DCD) is a neurodevelopmental disorder occurring in 5-6% of school-aged children. Converging evidence suggests that dysfunction within cortico-striatal and cortico-cerebellar networks may contribute to motor deficits in DCD, yet limited research has examined the brain morphology of these regions. Using T1-weighted magnetic resonance imaging the current study investigated cortical and subcortical volumes in 37 children with DCD, aged 8 to 12 years, and 48 controls of a similar age. Regional brain volumes of the thalamus, basal ganglia, cerebellum and primary motor and sensory cortices were extracted using the FreeSurfer recon-all pipeline and compared between groups. Reduced volumes within both the left and right pallidum (Left: F = 4.43, p = 0.039; Right: F = 5.24, p = 0.025) were observed in children with DCD; however, these results did not withstand correction for multiple comparisons. These findings provide preliminary evidence of altered subcortical brain structure in DCD. Future studies that examine the morphology of these subcortical regions are highly encouraged in order replicate these findings.

Do executive functions and gross motor skills predict writing and mathematical performance in children with developmental coordination disorder?

Aim: To examine whether executive functions, and gross motor skills were predictors for school performance in children with DCD, with risk for DCD (r-DCD), and with typical development (TD).Methods: Participants were 63 children with DCD (M_age = 8.70, SD_age = .64), 31 children with r-DCD (M_age = 8.90, SD_age = 0.74), and 63 typical development children (M_age = 8.74, SD_age = .63). Wechsler Abbreviated Scale of Intelligence, Movement Assessment Battery for Children-2, Test of Gross Motor Development-3, Oral Word Span in Sentences, Odd-One-Out, Go/No-Go, Hayling Test, Trail Making Test, Five Digits Test, and the Test of School Performance-II were utilized.Results: In DCD, processing speed (β = -.42, p = .005), and auditory-motor inhibition (β = -.36, p = .009), and auditory-verbal inhibition (β = -.38, p = .023) predicted math performance; and auditory-motor (β = -.40, p = .38) and visuospatial working memory (β = -.33 p = .011) predicted writing performance. In r-DCD, auditory-motor (β = - .67; p = .002) and visual-motor (β = -.40; p = .040) inhibition predicted math performance; visual-motor inhibition predicted writing performance (β = -.47; p = .015).Conclusion: Lower inhibitory control and visuospatial working memory scores affect children with DCD and r-DCD' school performance.

Top-down Inhibitory Motor Control Is Preserved in Adults with Developmental Coordination Disorder

Two paradigms were employed to disentangle information processing from executive motor inhibition in adults with Developmental Coordination Disorder (DCD). Choice Reaction and Stop Signal Tasks were compared between 13 adults fulfilling DSM-5 DCD criteria and 42 typically developing adults. Additional analyses included 16 probable DCD (pDCD) participants, who had motor difficulties but did not fulfil DSM-5 criteria. Analyses employed frequentist and Bayesian modeling. While DCD+pDCD showed slower reaction times and difficulty initiating Go responses, no impairments in Stop actions were found. These findings indicated no executive deficit in DCD, suggesting that previous results may be explained by inefficient information processing.

Attentional and executive functions in children and adolescents with developmental coordination disorder and the influence of comorbid disorders: A systematic review of the literature

Developmental coordination disorder (DCD) is a neurodevelopmental disorder affecting primarily motor skills, but attentional and executive impairments are common in affected individuals. Moreover, the presence of neurodevelopmental comorbidities is frequent in this population, which certainly influences the cognitive profile of the children concerned. Previous studies have reported deficits in visuospatial/nonverbal and planning tasks. This systematic review of the literature aims to determine if impairments can be found in other attentional and executive functions as well. The type of cognitive tasks, the tasks’ modality (verbal/nonverbal), and the influence of comorbid disorders on attentional and executive profiles are systematically considered. Forty-one studies were identified through the PubMed/Medline and PsycINFO databases according to pre-established eligibility criteria. The results reveal weaknesses in inhibitory control, working memory, planning, nonverbal fluency, and general executive functioning in children with DCD. The presence of comorbid disorders seemingly contributes to the verbal working memory difficulties findings. This review contributes to a better understanding of the cognitive impairments in DCD and of the needs of children with this disorder, allowing to optimize practitioners’ therapeutic interventions.

Evoked Potentials Differentiate Developmental Coordination Disorder From Attention-Deficit/Hyperactivity Disorder in a Stop-Signal Task: A Pilot Study

Developmental Coordination Disorder and Attention-Deficit/Hyperactivity Disorder are unique neurodevelopmental disorders with overlaps in executive functions and motor control. The conditions co-occur in up to 50% of cases, raising questions of the pathological mechanisms of DCD versus ADHD. Few studies have examined these overlaps in adults with DCD and/or ADHD. Therefore, to provide insights about executive functions and motor control between adults with DCD, ADHD, both conditions (DCD + ADHD), or typically developed controls, this study used a stop-signal task and parallel EEG measurement. We assessed executive performance via go accuracy and go reaction time, as well as motor response inhibition via stop-signal reaction time. This was complemented with analysis of event-related potentials (ERPs). Based on existing investigations of adults with DCD or ADHD, we expected (1) groups would not differ in behavioral performance on stop and go trials, but (2) differences in ERPs, particularly in components N200 (index of cognitive control) and P300 (index of attention and inhibition) would be evident. The sample included N = 50 adults with DCD (n = 12), ADHD (n = 9), DCD + ADHD (n = 7), and control participants (n = 22). We replicated that there were no between-group differences for behavioral-level executive performance and motor response inhibition. However, on a physiological level, ERP components N200 and P300 differed between groups, particularly during successful response inhibition. These ERPs reflect potential endophenotypic differences not evident in overt behavior of participants with ADHD and/or DCD. This suggests a disorder specific employment of inhibition or general executive functions in groups of adults with DCD, DCD + ADHD, ADHD, or control participants.

Laterality and visuospatial strategies among young children: A novel 3D-2D transcription task

Recent findings showed that children, like adults, exhibit directional biases leading to asymmetrical drawings. This appears to be the result of a complex interaction between several biological, motoric, and cultural factors. We created a drawing task designed to investigate the influence of laterality (i.e., hemispherical functional specialization and handedness) and sex on children's graphical asymmetries. This task consists of transcribing a symmetrical three-dimensional landscape model to a two-dimensional representation. Sixty-six French pre-school children, aged between 5 and 6 years, were asked to undertake the 3D-2D transcription task, as well as the classical Alter's directionality task. The novel task exhibited higher sensitivity than the Alter's directionality test when examining the spatial biases resulting from handedness, and sex. Specific drawing patterns related to these variables were identified. These results suggest that, in addition to the influence of biomechanical factors and handedness, sex plays a role in children's early graphomotor development. They also support the influence of laterality as a key factor underlying early directional biases.

Error-Related Cognitive Control and Behavioral Adaptation Mechanisms in the Context of Motor Functioning and Anxiety

Motor proficiency reflects the ability to perform precise and coordinated movements in different contexts. Previous research suggests that different profiles of motor proficiency may be associated with different cognitive functioning characteristics thus suggesting an interaction between cognitive and motor processes. The current study investigated this interaction in the general population of healthy adults with different profiles of motor proficiency by focusing on error-related cognitive control and behavioral adaptation mechanisms. In addition, the impact of these processes was assessed in terms of trait anxiety and worries. Forty healthy adults were divided into high and low motor proficiency groups based on an assessment of their motor skills. Using electroencephalography during a flanker task, error-related negativity (ERN) was measured as the neural indicator of cognitive control. Post-error slowing (PES) was measured to represent behavioral adaptation. Participants also completed an anxiety assessment questionnaire. Participants in the high motor proficiency group achieved better task accuracy and showed relatively enhanced cognitive control through increased ERN. Contrastingly, individuals in the lower motor proficiency group achieved poorer accuracy whilst showing some evidence of compensation through increased PES. Trait anxiety reflecting general worries was found to be correlated with motor functioning, but the study could not provide evidence that this was related to cognitive or behavioral control mechanisms. The interaction between cognitive and motor processes observed in this study is unique for healthy and sub-clinical populations and provides a baseline for the interpretation of similar investigations in individuals with motor disorders.

Neural Basis and Motor Imagery Intervention Methodology Based on Neuroimaging Studies in Children With Developmental Coordination Disorders: A Review

Although the neural bases of the brain associated with movement disorders in children with developmental coordination disorder (DCD) are becoming clearer, the information is not sufficient because of the lack of extensive brain function research. Therefore, it is controversial about effective intervention methods focusing on brain function. One of the rehabilitation techniques for movement disorders involves intervention using motor imagery (MI). MI is often used for movement disorders, but most studies involve adults and healthy children, and the MI method for children with DCD has not been studied in detail. Therefore, a review was conducted to clarify the neuroscientific basis of the methodology of intervention using MI for children with DCD. The neuroimaging review included 20 magnetic resonance imaging studies, and the neurorehabilitation review included four MI intervention studies. In addition to previously reported neural bases, our results indicate decreased activity of the bilateral thalamus, decreased connectivity of the sensory-motor cortex and the left posterior middle temporal gyrus, bilateral posterior cingulate cortex, precuneus, cerebellum, and basal ganglia, loss of connectivity superiority in the abovementioned areas. Furthermore, reduction of gray matter volume in the right superior frontal gyrus and middle frontal gyrus, lower fractional anisotropy, and axial diffusivity in regions of white matter pathways were found in DCD. As a result of the review, children with DCD had less activation of the left brain, especially those with mirror neurons system (MNS) and sensory integration functions. On the contrary, the area important for the visual space processing of the right brain was activated. Regarding of characteristic of the MI methods was that children observed a video related to motor skills before the intervention. Also, they performed visual-motor tasks before MI training sessions. Adding action observation during MI activates the MNS, and performing visual-motor tasks activates the basal ganglia. These methods may improve the deactivated brain regions of children with DCD and may be useful as conditioning before starting training. Furthermore, we propose a process for sharing the contents of MI with the therapist in language and determining exercise strategies.

Children with developmental coordination disorder show altered functional connectivity compared to peers

Developmental Coordination Disorder (DCD) is a neurodevelopmental disorder that affects a child's ability to learn motor skills and participate in self-care, educational, and leisure activities. The cause of DCD is unknown, but evidence suggests that children with DCD have atypical brain structure and function. Resting-state MRI assesses functional connectivity by identifying brain regions that have parallel activation during rest. As only a few studies have examined functional connectivity in this population, our objective was to compare whole-brain resting-state functional connectivity of children with DCD and typically-developing children. Using Independent Component Analysis (ICA), we compared functional connectivity of 8-12 year old children with DCD (N = 35) and typically-developing children (N = 23) across 19 networks, controlling for age and sex. Children with DCD demonstrate altered functional connectivity between the sensorimotor network and the posterior cingulate cortex (PCC), precuneus, and the posterior middle temporal gyrus (pMTG) (p < 0.0001). Previous evidence suggests the PCC acts as a link between functionally distinct networks. Our results indicate that ineffective communication between the sensorimotor network and the PCC might play a role in inefficient motor learning seen in DCD. The pMTG acts as hub for action-related information and processing, and its involvement could explain some of the functional difficulties seen in DCD. This study increases our understanding of the neurological differences that characterize this common motor disorder.

Executive function in children with and without developmental coordination disorder: A comparative study

BACKGROUND

Children with motor impairments also show poor performance in some executive functions' components. However, there is no consensus on which specific executive subdomain is more impacted.

AIM

The objective of this study was to compare executive functions in children with developmental coordination disorder (DCD), at risk for DCD (r-DCD), and in typically developing (TD) children.

METHODS AND PROCEDURES

A sample of 397 children was assessed using the MABC-2. Two groups of children were identified; DCD (n = 63) and at r-DCD (n = 31). A third matched group of children with TD (n = 63) was formed. The MABC-2 checklist and the WASI tests were used as screening tools. Measures of executive function including verbal and nonverbal tasks for working memory, inhibitory control, and cognitive flexibility were tested. Multivariate analysis of variance followed by analyses of variance and Bonferroni tests were used to verify group effects on executive functions.

RESULTS

A significant group effects were found for Working Memory, Λ = .78, F(4, 360) = 10.12, p ≤ .001, η_p² = .12; Inhibitory Control, Λ = .59, F(16, 294) = 5.48, p ≤ .001, η_p² = .23; and Cognitive Flexibility and Inhibitory Control, Λ = .60, F(22, 288) = 3.74, p ≤ .001, η_p² = .22, with moderate effect sizes. The DCD group showed lower scores compared with the TD group on the visuospatial and verbal working memory; inhibitory control and in tasks of cognitive flexibility; the r-DCD group showed lower scores compared with the TD group for visuospatial working memory and for cognitive flexibility.

CONCLUSIONS AND IMPLICATIONS

Poor performance in several measures of executive functions in children with DCD emphasized the need of motor/executive task-specific interventions. Furthermore, children at r-DCD showed low scores in several executive functions; therefore, preventive services should also be provided for this subclinical group.

Reduced Nogo-P3 in adults with developmental coordination disorder (DCD)

Nogo-N2 is associated with the premotor cognitive process that precedes motor response (e.g., conflict monitoring), whereas Nogo-P3 is related to the inhibition of the actual motor response. We examined the influence of motor clumsiness of developmental coordination disorder (DCD) on components of the event-related potential in a Go/Nogo task. Participants were healthy adults (N = 81) that were classified into control and DCD groups based on the Movement Assessment Battery for Children Second Edition. We manipulated the difficulty in stopping a response by varying the frequency of Nogo stimuli in a response task into rare (20%) and frequent (80%) conditions, and Nogo-N2 and Nogo-P3 were calculated from electroencephalograms (EEGs) during the Go/Nogo tasks. The commission error rate in the rare condition was significantly higher in the DCD group than in the control group, indicating that motor clumsiness decreases task performance. There were no differences in Nogo-N2 between DCD and control groups. However, Nogo-P3 in the rare condition was reduced in the DCD group compared to the control group. These results suggest that the influence of motor clumsiness is limited to the cognitive process after the initiation of the actual motor response.

Motor and verbal inhibitory control: Development and validity of the go/No-Go app test for children with development coordination disorder

A set of inhibitory control tasks for the smartphone (Go/No-Go App) was developed for typical children and children with development coordination disorder (DCD). The content, construct, and criterion validity was examined. The inhibitory control Go/No-Go App test is comprised of four tasks: auditory and visual stimuli with motor and verbal responses. Six experts in neuropsychology and 252 Brazilian children (139 boys; 113 girls) participated in the study, including a subgroup of children with DCD (n = 53). A high level of agreement for clarity and pertinence was observed among the experts (Gwet's Agreement Coefficients > .09), highlighting its content validity. Suitable Cronbach's alpha and McDonald's omega results were observed. The confirmatory factorial analysis (CFA) accepted the results for the Auditory-Motor (γ = .83), Visual-Motor (γ = .73), Auditory-Verbal (γ = .67) and Visual-Verbal (γ = .73) tasks. The model presented adequate adjustment indexes (Chi-square = .48, p = .787), 2/DF = .24; RMSEA = .00; GFI = .99; CFI = 1.00; AIC = 326.90. The Go/No-Go app is a test with adequate validity for the assessment of inhibition in children with DCD and may be very helpful due to the variation of the stimuli and the responses.

Developmental coordination disorder

Developmental coordination disorder (DCD) is a neurodevelopmental disorder that affects children's ability to execute coordinated motor actions, resulting in slow, clumsy, or inaccurate motor performances and learning difficulties (of new motor tasks or to adapt previously learned gestures to a modified or additional constraint). In the course of development, children with DCD exhibit a diversity of motor signs, including fine and gross motor problems with impaired postural control and balance, and sensorimotor coordination or motor learning difficulties. The prevalence ranges between 1.8% and 8%, depending on the diagnostic criteria used, based on the cutoff of motor scores from standardized scales. Four main hypotheses have been postulated to explain DCD in terms of deficits in visuospatial functions, procedural learning, internal modeling, or executive functions. Neuroimaging studies are scarce but have highlighted several brain regions, including the parietal, frontal, and cerebellar cortices. Meta-analyses have supported task-oriented approaches as effective therapies to improve motor performance in children with DCD.

Motor intervention with and without Nintendo® Wii for children with developmental coordination disorder: protocol for a randomized clinical trial

BACKGROUND

Despite the benefits highlighted by motor interventions based on virtual reality for children with Developmental Coordination Disorder (DCD), there are still doubts as to whether these are greater than those obtained with conventional interventions due to the absence of systematized protocols, and lack of evidence. Here, we present a protocol to systematically compare the effects of two motor-training programs (one Nintendo® Wii-based and the other no-Wii motor activities) on the motor learning in children with DCD.

METHODS/DESIGN

Two intervention protocols (one based on Nintendo® Wii and the other no-Wii motor activities) will be carried out, with interventions occurring twice a week in 60-min sessions, with a minimum of 12 and a maximum of 16 sessions per child. The protocols were developed based on the domains of the Movement Assessment Battery for Children - Second Edition (MABC-2) (Manual Dexterity, Aiming and Catching, Balance), with two activities for each of the MABC - two domains. The study will include children aged 7 to 10 years with a total MABC-2 score ≤ 16, and a Developmental Coordination Disorder Questionnaire (DCDQ) score < 46 (age of 7 years), score < 55 (age group of 8 to 9 years and 11 months), or score < 57 (age of 10 years) as scored by the parents. Children will be randomly allocated by draw in one of the two intervention protocols. MABC-2 and DCDQ will be applied before and after intervention to evaluate the effects of the interventions on motor performance and parents' perception, respectively. Motor learning will be assessed by means of the scores obtained in the games. Evaluators and therapists will be trained and evaluators will be blind regarding the data of the children in the study.

DISCUSSION

Owing to its motivating aspects, training with Nintendo® Wii may be particularly beneficial for children with DCD. The results of this study protocol should help researchers and therapists to better understand the benefits of Nintendo® Wii-based motor intervention over those obtained with no-Wii interventions in children with DCD. It should also create references about more systematized protocols for replication in clinical practice, seeking the improvement of the motor components of these children.

TRIAL REGISTRATION

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Fractal fluctuations in exploratory movements predict differences in dynamic touch capabilities between children with Attention-Deficit Hyperactivity Disorder and typical development

Children with Attention-Deficit Hyperactivity Disorder (ADHD) struggle to perform a host of daily activities. Many of these involve forceful interaction with objects and thus implicate dynamic touch. Therefore, deficits in dynamic touch could underlie functional difficulties presented by ADHD children. We investigated whether performance on a dynamic touch task (length perception by wielding) differ between children with ADHD and age-matched controls. We further examined whether this difference could be explained by fractal temporal correlations (wielding dynamics). Forty-two children (ADHD: 21; typically developing: 21) wielded unseen wooden rods and reported their perceived length in the form of magnitude productions. The rods varied in the magnitude of the first principal moment of inertia (I₁). Three-dimensional displacements of hand and rod positions were submitted to Detrended Fluctuation Analysis to estimate trial-by-trial temporal correlations. Children with ADHD reported shorter length for rods with higher I₁ than their typically developing peers, indicative of reduced sensitivity to mechanical information supporting dynamic touch. Importantly, temporal correlations in wielding dynamics moderated children’s usage of I_1. This finding points to a role of exploratory movements in perceptual deficits presented by children with ADHD and, thus, should be considered a new potential target for interventions.

Adults with probable developmental coordination disorder selectively process early visual, but not tactile information during action preparation. An electrophysiological study

Developmental coordination disorder (DCD) is a neurodevelopmental condition affecting motor coordination in children and adults. Here, EEG signals elicited by visual and tactile stimuli were recorded while adult participants with and without probable DCD (pDCD) performed a motor task. The task cued reaching movements towards a location in visible peripersonal space as well as an area of unseen personal space. Event-related potentials elicited by visual and tactile stimuli revealed that visual processing was strongly affected by movement preparation in the pDCD group, even more than in controls. However, in contrast to the controls, tactile processing in unseen space was unaffected by movement preparation in the pDCD group. The selective use of sensory information from vision and proprioception is fundamental for the adaptive control of movements, and these findings suggest that this is impaired in DCD. Additionally, the pDCD group showed attenuated motor rhythms (beta: 13-30 Hz) over sensorimotor regions following cues to prepare movements towards unseen personal space. The results reveal that individuals with pDCD exhibit differences in the neural mechanisms of spatial selection and action preparation compared to controls, which may underpin the sustained difficulties they experience. These findings provide new insights into the neural mechanisms potentially disrupted in this highly prevalent disorder.

A Review of Functional and Structural Neurobiology of the Action Observation Network in Autism Spectrum Disorder and Developmental Coordination Disorder

Recent research has reported motor impairment similarities between children with developmental coordination disorder (DCD) and a subgroup of individuals with autism spectrum disorder (ASD). However, there is a debate as to whether DCD is a co-occurring diagnosis in individuals with ASD and motor impairments (ASDd), or if motor impairments in ASD are distinct from DCD. However, the etiology of motor impairments is not well understood in either disorder. Clarifying comorbidities in ASD is important to determine different etiopathological phenotyping clusters in ASD and to understand the variety of genetic and environmental factors that contribute to the disorder. Furthermore, this distinction has important therapeutic relevance. Here we explore the current neuroimaging findings in ASD and DCD and discusses possible neural mechanisms that underlie similarities and differences between the disorders.

Mirror neuron system activation in children with developmental coordination disorder: A replication functional MRI study

BACKGROUND

It has been hypothesised that abnormal functioning of the mirror neuron system (MNS) may lead to deficits in imitation and the internal representation of movement, potentially contributing to the motor impairments associated with developmental coordination disorder (DCD).

AIMS

Using fMRI, this study examined brain activation patterns in children with and without DCD on a finger adduction/abduction task during four MNS activation states: observation; motor imagery; execution; and imitation.

METHODS AND PROCEDURES

Nineteen boys (8.25-12.75 years) participated, including 10 children with DCD (≤16th percentile on MABC-2; no ADHD/ASD), and nine typically developing controls (≥25th percentile on MABC-2).

OUTCOMES AND RESULTS

Even though children with DCD displayed deficits behaviourally on imitation (Sensory Integration & Praxis Test Subtests) and motor imagery assessments prior to scanning, no differences in MNS activation were seen between the DCD and control groups at a neurological level, with both groups activating mirror regions effectively across conditions. Small clusters of decreased activation during imitation were identified in non-mirror regions in the DCD group, including the thalamus, caudate, and posterior cingulate - regions involved in motor planning and attentional processes.

CONCLUSIONS AND IMPLICATIONS

The results of this study do not provide support for the MNS dysfunction theory as a possible causal mechanism for DCD. Further research to explore attentional and motor planning processes and how they may interact at a network level may enhance our understanding of this complex disorder.

Is virtual reality effective in improving the motor performance of children with developmental coordination disorder? A systematic review

INTRODUCTION

Although virtual reality (VR) is an increasingly popular approach within studies that propose interventions for children with developmental coordination disorder (DCD), evidence on the effectiveness of VR remains debatable. The aim of this study was to synthesize evidence on the effectiveness of VR interventions for motor performance improvement in children with DCD.

EVIDENCE ACQUISITION

Searches were conducted in the MEDLINE/PubMed, Scopus, Web of Science and ERIC databases to select studies published from 1 January 2006 to 30 November 2017. Two independent reviewers performed the primary study selection based on titles, abstracts and full-text reading; this selection included randomized controlled trials (RCTs) that applied VR interventions to children with DCD and assessed outcomes related to motor performance. The methodological quality of the studies included in the search was assessed through the PEDro scale. PRISMA guidelines and Cochrane recommendations for systematic reviews were followed. The effect size of each intervention was calculated to allow for the interpretation of clinical effects, and the body of evidence was synthesised through the GRADE approach.

EVIDENCE SYNTHESIS

A total of 2160 publications were retrieved; by the end of the selection process, twelve RCTs had been included. Of these twelve, seven were classified as having high methodological quality. Only three studies satisfied the homogeneity conditions to be assessed through the GRADE system, which showed a low level of evidence in favor of VR for improving the motor performance of children with DCD.

CONCLUSIONS

Not enough evidence currently exists to support or refute the use of VR over non-VR interventions for improving motor performance in children with DCD. Despite the potential for improving the motor performance of DCD children, the absence of specific protocols prevents formal recommendations of VR for these children. Future studies should consider VR protocols that are more specific regarding the tasks, features and target motor skills to be developed by DCD children. In addition, comparisons of similar groups at baseline, the concealment of allocation and the blinding of assessors are internal validity aspects which deserve researchers' attention.

Linear and Nonlinear Analyses of the Cardiac Autonomic Control in Children With Developmental Coordination Disorder: A Case-Control Study

Children with Developmental Coordination Disorder (DCD) and children at risk for DCD (r-DCD) present motor impairments interfering in their school, leisure and daily activities. In addition, these children may have abnormalities in their cardiac autonomic control, which together with their motor impairments, restrict their health and functionality. Therefore, this study aimed to assess the cardiac autonomic control, by linear and nonlinear analysis, at supine and during an orthostatic stimulus in DCD, r-DCD and typically developed children. Thirteen DCD children (11 boys and 2 girls, aged 8.08 ± 0.79 years), 19 children at risk for DCD (13 boys and 6 girls, aged 8.10 ± 0.96 years) and 18 typically developed children, who constituted the control group (CG) (10 boys and 8 girls, aged 8.50 ± 0.96 years) underwent a heart rate variability (HRV) examination. R-R intervals were recorded in order to assess the cardiac autonomic control using a validated HR monitor. HRV was analyzed by linear and nonlinear methods and compared between r-DCD, DCD, and CG. The DCD group presented blunted cardiac autonomic adjustment to the orthostatic stimulus, which was not observed in r-DCD and CG. Regarding nonlinear analysis of HRV, the DCD group presented lower parasympathetic modulation in the supine position compared to the r-DCD and CG groups. In the within group analysis, only the DCD group did not increase HR from supine to standing posture. Symbolic analysis revealed a significant decrease in 2LV (p < 0.0001) and 2UV (p < 0.0001) indices from supine to orthostatic posture only in the CG. In conclusion, r-DCD and DCD children present cardiac autonomic dysfunction characterized by higher sympathetic, lower parasympathetic and lower complexity of cardiac autonomic control in the supine position, as well as a blunted autonomic adjustment to the orthostatic stimulus. Therefore, cardiovascular health improvement should be part of DCD children's management, even in cases of less severe motor impairment.

Interhemispheric Cortical Inhibition Is Reduced in Young Adults With Developmental Coordination Disorder

Introduction

While the etiology of developmental coordination disorder (DCD) is yet to be established, brain-behavior modeling provides a cogent argument that neuropathology may subserve the motor difficulties typical of DCD. We argue that a number of the core behavioral features of the DCD profile (such as poor surround inhibition, compromised motor inhibition, and the presence of mirror movements) are consistent with difficulties regulating inhibition within the primary motor cortex (M1). This study aimed to be the first account of the integrity of cortical inhibition in motor cortices in DCD.

Method

The sample consisted of eight adults with DCD aged (18–30 years) and 10 aged matched neurotypical controls. Participants received a common battery of single and paired-pulse transcranial magnetic stimulation from which a series of neurophysiological measures classically used to measure intra- [e.g., short-interval cortical inhibition (SICI), long-interval cortical inhibition (LICI), and cortical silent period] and inter hemispheric [e.g., ipsilateral silent period (ISP)] cortical inhibition of the M1 at rest were recorded.

Results

While no group differences were observed for any measure of intrahemispheric cortical inhibition, individuals with DCD demonstrated significantly reduced interhemispheric cortical inhibition relative to controls, shown by consistently lower ISP_ratios.

Conclusion

Our findings are consistent with the view that regulation of cortical inhibition of M1 activity may be atypical in individuals with DCD, indicating differential GABAergic operation. This effect, however, appears to be select to cortical inhibition. Importantly, our data support the notion that reduced interhemispheric M1 cortical inhibition may at least partly explain commonly reported difficulties with bimanual motor control in DCD. The neurochemical implications and limitations of this evidence will be discussed.

Deficits in Visuo-Motor Temporal Integration Impacts Manual Dexterity in Probable Developmental Coordination Disorder

The neurological basis of developmental coordination disorder (DCD) is thought to be deficits in the internal model and mirror-neuron system (MNS) in the parietal lobe and cerebellum. However, it is not clear if the visuo-motor temporal integration in the internal model and automatic-imitation function in the MNS differs between children with DCD and those with typical development (TD). The current study aimed to investigate these differences. Using the manual dexterity test of the Movement Assessment Battery for Children (second edition), the participants were either assigned to the probable DCD (pDCD) group or TD group. The former was comprised of 29 children with clumsy manual dexterity, while the latter consisted of 42 children with normal manual dexterity. Visuo-motor temporal integration ability and automatic-imitation function were measured using the delayed visual feedback detection task and motor interference task, respectively. Further, the current study investigated whether autism-spectrum disorder (ASD) traits, attention-deficit hyperactivity disorder (ADHD) traits, and depressive symptoms differed among the two groups, since these symptoms are frequent comorbidities of DCD. In addition, correlation and multiple regression analyses were performed to extract factors affecting clumsy manual dexterity. In the results, the delay-detection threshold (DDT) and steepness of the delay-detection probability curve, which indicated visuo-motor temporal integration ability, were significantly prolonged and decreased, respectively, in children with pDCD. The interference effect, which indicated automatic-imitation function, was also significantly reduced in this group. These results highlighted that children with clumsy manual dexterity have deficits in visuo-motor temporal integration and automatic-imitation function. There was a significant correlation between manual dexterity, and measures of visuo-motor temporal integration, and ASD traits and ADHD traits and ASD. Multiple regression analysis revealed that the DDT, which indicated visuo-motor temporal integration, was the greatest predictor of poor manual dexterity. The current results supported and provided further evidence for the internal model deficit hypothesis. Further, they suggested a neurorehabilitation technique that improved visuo-motor temporal integration could be therapeutically effective for children with DCD.