Impaired visuo-motor sequence learning in Developmental Coordination Disorder

The defining feature of Developmental Coordination Disorder (DCD) is the marked impairment in the development of motor coordination (DSM-IV-TR, American Psychiatric Association, 2000). In the current study, we focused on one core aspect of motor coordination: learning to correctly sequence movements. We investigated the procedural, visuo-motor sequence learning abilities of 18 children with DCD and 20 matched typically developing (TD) children, by means of the serial reaction time (SRT) task. Reaction time measurements yielded two important findings. Overall, DCD children demonstrated general learning of visuo-motor task demands comparable to that of TD children but failed to learn the visuo-motor sequence. Interestingly, a sequence recall test, administered after the SRT task, indicated some awareness of the repeating sequence pattern. This suggests that the sequence learning problems of DCD children might be located at the stage of motor planning rather than sequence acquisition.     

Aspects of grammar sensitive to procedural memory deficits in children with specific language impairment

Procedural deficit hypothesis claims that language deficit in children with specific language impairment is affiliated to sequence learning problems. However, studies did not explore on aspects of grammar vulnerable to sequence learning deficits. The present study makes predictions for aspects of grammar that could be sensitive to procedural deficits based on core ideas of procedural deficit hypothesis. The hypothesis for the present study was that the grammatical operations that require greater sequencing abilities (such as inflectional operations) would be more affected in children with language impairment. Further, the influence of sequencing difficulties would be even greater in agglutinating inflectional languages. An adapted serial reaction time task for sequence learning measurements along with grammatical tasks on derivation, inflection, and sentence complexity were examined on typically developing and language impaired children. Results were in favor of procedural deficit hypothesis and its close relation to non-adjacent grammatical operations. The findings were discussed using procedural deficits, declarative compensatory mechanism, and statistical learning deficits.     

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.     

Sequence learning in Parkinson's disease: a comparison of spatial-attention and number-response sequences

The serial reaction time (SRT) task has been frequently used to assess procedural learning of sequences. Patients with Parkinson's disease (PD) have been reported to show deficits on this task, but it is as yet unclear whether this impairment reflects a general sequencing deficit or a deficit in the sequencing of motor-output responses. In order to examine this issue, PD patients and controls were administered an SRT task which allowed the simultaneous and independent assessment of the procedural learning of spatial regularities and the learning of motor-response regularities. PD patients were unimpaired at learning a sequence of spatial locations, but showed a deficit at learning a stimulus-to-motor-response sequence. The results suggest that sequencing impairments in PD are not general, but specific to the type of sequential information inherent in a task.     

Mathematical problems in children with developmental coordination disorder

Developmental coordination disorder (DCD) is a heterogeneous disorder, which is often co-morbid with learning disabilities. However, mathematical problems have rarely been studied in DCD. The aim of this study was to investigate the mathematical problems in children with various degrees of motor problems. Specifically, this study explored if the development of mathematical skills in children with DCD is delayed or deficient. Children with DCD performed significantly worse for number fact retrieval and procedural calculation in comparison with age-matched control children. Moreover, children with mild DCD differed significantly from children with severe DCD on both number fact retrieval and procedural calculation. In addition, we found a developmental delay of 1 year for number fact retrieval in children with mild DCD and a developmental delay of 2 years in children with severe DCD. No evidence for a mathematical deficit was found. Diagnostic implications are discussed.     

A staged approach for identifying children with developmental coordination disorder from the population

The purpose of this study was to describe the motor, attention and intellectual characteristics of a population-based sample of children first screened for motor impairment and to discuss the recruitment and identification methods employed. A two stage cross-sectional, school-based survey was conducted to screen for children with motor coordination difficulties and to identify children with an existing diagnosis of attention deficit hyperactivity disorder/attention deficit disorder (ADHD/ADD). The identified children, and a random sample of typically developing children, were assessed to confirm or rule out the presence of developmental coordination disorder (DCD).Six thousand four hundred and seventy five children were invited to participate; 2943 children, with parental consent, completed the initial screening process. Two hundred eighty four children with possible motor impairment were identified. The parents of 113 children consented to a full assessment. Sixty eight children of the 113 children met diagnostic criteria for DCD, and 26 also had ADHD. Twenty eight of the 55 children who screened in with a diagnosis of ADHD were subsequently found to have DCD. The total number of children with confirmed characteristics of DCD was reduced after application of DCD diagnostic criteria. This study differs from others with regard to the additional screening for children with ADHD/ADD. The second stage assessment notably increased the number of children identified with both ADHD and DCD.     

Procedural learning is impaired in Huntington's disease: evidence from the serial reaction time task.

The purpose of the study was to test the hypothesis that Huntington's disease (HD) is associated with impairment of procedural learning. We identified 13 patients with mild to moderate HD whose manual performance was still sufficiently intact to assess learning on the serial reaction time (SRT) task. Twelve age-matched neurologically normal control subjects were studied as well. The SRT task was a four-choice reaction time task in which the stimuli followed a sequence (10 items in length) which repeated itself 10 times during each of the first four blocks of trials. During the fifth block of trials, the stimuli were random. Learning was manifested by a reduction in response latency over the first four blocks and an increase in response latency in the fifth (random) block. Learning in this task has been demonstrated in other amnesics of other etiologies. The HD patients were significantly impaired on sequence-specific learning, using the log-transformed reaction time data (P less than 0.004). In addition, in an individual-by-individual analysis, five of the HD patients and none of the control subjects failed to show sequence-specific learning, a difference in proportions that was significant (P less than 0.04). No feature of the standard cognitive or motor assessment of the HD patients was associated with efficacy of procedural learning. HD, including patients with mild disease, was associated with a deficit in procedural learning, consistent with the hypothesis that the striatum plays a critical role in supporting procedural learning.     

Sequences assessed by declarative and procedural tests of memory in amnesic patients with hippocampal damage

Previous research indicates that amnesic subjects tested on sequential learning or serial reaction time tasks can learn a repeated procedural sequence but are unable to explicitly recall the correct sequence when asked to generate the sequence. Rats with hippocampal lesions are also able to learn and remember procedural or implicit sequences but were impaired for declarative sequences. We used analogous procedures used in rats to assess the role of the hippocampus in the acquisition of declarative and procedural sequences in amnesic and control participants. Amnesic participants with damage restricted to the hippocampus and control participants were administered analogous tasks of declarative and procedural sequential learning using a computer version of the radial arm maze. The amnesic participants had slower response times during the acquisition of procedural sequences, but were not impaired compared to controls when switched to a random sequence, suggesting that both groups learned the sequence. Alternatively, the amnesic but not control participants were significantly impaired in the declarative sequence task. Our findings provide support for evolutionary continuity in cognitive function of the hippocampus in rats and humans and the dissociation between the declarative and procedural sequential learning. The performance differences on the two sequence learning tasks are likely due to the use of different strategies associated with learning sequences based on procedural versus declarative knowledge.     

Motor imagery and action observation for predictive control in developmental coordination disorder

In 2019, international clinical practice recommendations on the definition, diagnosis, assessment, intervention, and psychosocial aspects of developmental coordination disorder (DCD) were published. Informing our understanding of mechanisms, recent systematic reviews have shown that children with DCD have difficulties with the predictive control of movements, including aspects of motor planning, which is expressed as the internal modeling deficit hypothesis. This motor control deficit is most evident when the spatial and temporal demands of a task increase. An increasing number of empirical studies suggest that motor planning problems can be remediated through training based on one or a combination of motor imagery and action observation. In this review, we show evidence of motor planning problems in children with DCD and show that task demands or complexity affects its appearance. Implications of these findings are treatments based on motor imagery and action observation to remediate motor planning issues. The article concludes with recommendations for future research.     

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.     

Implicit sequence learning in obsessive-compulsive disorder: further support for the fronto-striatal dysfunction model.

BACKGROUND: Obsessive-compulsive disorder (OCD) is conceived as a disease that implicates dysfunctions in fronto-striatal brain systems. According to this model, performance deficits observed in patients with lesions in these brain areas are hypothesized to be present also in OCD patients. Implicit procedural learning, which refers to the acquisition of motor or nonmotor skills by practice, is one candidate function to test this prediction. METHODS: The serial reaction time task was used to assess implicit sequence learning of 33 patients with a diagnosis of OCD and 27 healthy control participants. In addition, explicit (i.e., conscious) knowledge of the sequence was determined. A subgroup of 24 patients was reassessed after intensive cognitive-behavioral psychotherapy. RESULTS: Implicit sequence learning was significantly reduced in the OCD group by 41%, while explicit learning and verbal abilities were unaffected. The deficit remained stable across time, although symptoms remitted substantially. Depressive symptoms did not account for the finding. Partial explicit knowledge of the sequence was not a predictor of the amount of implicit learning. CONCLUSIONS: Reduced implicit learning appears to be a dissociable trait of OCD patients. The results confirm previous findings and add supportive evidence for the fronto-striatal dysfunction model of OCD.     

Motor and gestural performance in children with autism spectrum disorders, developmental coordination disorder, and/or attention deficit hyperactivity disorder.

Motor and gestural skills of children with autism spectrum disorders (ASD), developmental coordination disorder (DCD), and/or attention deficit hyperactivity disorder (ADHD) were investigated. A total of 49 children with ASD, 46 children with DCD, 38 children with DCD+ADHD, 27 children with ADHD, and 78 typically developing control children participated. Motor skills were assessed with the Bruininks-Oseretsky Test of Motor Proficiency Short Form, and gestural skills were assessed using a test that required children to produce meaningful gestures to command and imitation. Children with ASD, DCD, and DCD+ADHD were significantly impaired on motor coordination skills; however, only children with ASD showed a generalized impairment in gestural performance. Examination of types of gestural errors revealed that children with ASD made significantly more incorrect action and orientation errors to command, and significantly more orientation and distortion errors to imitation than children with DCD, DCD+ADHD, ADHD, and typically developing control children. These findings suggest that gestural impairments displayed by the children with ASD were not solely attributable to deficits in motor coordination skills.     

Memory consolidation in children with specific language impairment: Delayed gains and susceptibility to interference in implicit sequence learning

In this study, the time course of the procedural learning of a visuomotor sequence skill was followed over a 24-hour and a 1-week time period in children with and without specific language impairment (SLI). Two aspects of memory consolidation in implicit sequence learning were examined: the evolution of post-training gains in sequence knowledge (Experiment 1) and the susceptibility to interference (Experiment 2). In the first experiment, 18 children with SLI and 17 control children matched for sex, age, and nonverbal intelligence completed a serial reaction-time (SRT) task and were tested 24 hours and 1 week after practicing. The two groups of children attained an equal level of sequence knowledge in the training session, but the children with SLI lacked the consolidation gains displayed by the control children in the two post-training sessions. Working with a new group of children, 17 with SLI and 17 control peers, Experiment 2 examined resistance to interference by introducing a second sequence 15 min after the first training session. Similar results were obtained for the performance of both groups in the training session. However, although the performance of the control group improved in the post-training sessions, the performance of the SLI group deteriorated significantly during the consolidation phase due to the interfering sequence. These findings suggest that the consolidation phase of sequence learning is impaired in children with SLI.     

Neuromotor deficits in developmental coordination disorder: evidence from a reach-to-grasp task

Developmental coordination disorder (DCD) has been classified as a specific learning disability, nonetheless the underlying cognitive mechanisms are still a matter of discussion. After a summary of the main hypotheses on the principal neuromotor causes of DCD, this study applies a causal model framework to describe the possible coexistence of more than one deficit in this disorder. For this purpose, kinematic analysis was applied to an ecological task, the reach-to-grasp action, introducing the manipulation of three variables: vision, distance and object size. After a thorough neurological and neuropsychological evaluation, 9 children with DCD (7-9 years old) were selected and compared to 27 age-matched control children. The results suggest that children with DCD have a normal neurological characterization of the reaching and grasping movements, in terms of proximal to distal action, but their grasping aperture (MGA) was always wider with respect to controls, particularly when vision was not allowed. In addition, the performance of children with DCD was always slower, more dependent on vision and more variable than that of controls. The MGA of children with DCD could be explained by a deficit in the internal construction of movement for a forward model, while slowness could be related to a control problem in the neuronal firing of the muscles. The idea of a possible coexistence of these two deficits is discussed in accordance to a causal model framework and also addressed considering recent neurophysiologic evidences.     

What is the evidence of impaired motor skills and motor control among children with attention deficit hyperactivity disorder (ADHD)? Systematic review of the literature

This article presents a review of the studies that have analysed the motor skills of ADHD children without medication and the influence of medication on their motor skills. The following two questions guided the study: What is the evidence of impairment of motor skills and aspects of motor control among children with ADHD aged between 6 and 16 years? What are the effects of ADHD medication on motor skills and motor control? The following keywords were introduced in the main databases: attention disorder and/or ADHD, motor skills and/or handwriting, children, medication. Of the 45 articles retrieved, 30 described motor skills of children with ADHD and 15 articles analysed the influence of ADHD medication on motor skills and motor control. More than half of the children with ADHD have difficulties with gross and fine motor skills. The children with ADHD inattentive subtype seem to present more impairment of fine motor skills, slow reaction time, and online motor control during complex tasks. The proportion of children with ADHD who improved their motor skills to the normal range by using medication varied from 28% to 67% between studies. The children who still show motor deficit while on medication might meet the diagnostic criteria of developmental coordination disorder (DCD). It is important to assess motor skills among children with ADHD because of the risk of reduced participation in activities of daily living that require motor coordination and attention.     

Interference of left and right cerebellar rTMS with procedural learning

Increasing evidence suggests cerebellar involvement in procedural learning. To further analyze its role and to assess whether it has a lateralized influence, in the present study we used a repetitive transcranial magnetic stimulation interference approach in a group of normal subjects performing a serial reaction time task. We studied 36 normal volunteers: 13 subjects underwent repetitive transcranial magnetic stimulation on the left cerebellum and performed the task with the right (6 subjects) or left (7 subjects) hand; 10 subjects underwent repetitive transcranial magnetic stimulation on the right cerebellum and performed the task with the hand ipsilateral (5 subjects) or contralateral (5 subjects) to the stimulation; another 13 subjects served as controls and were not submitted to repetitive transcranial magnetic stimulation; 7 of them performed the task with the right hand and 6 with the left hand. The main results show that interference with the activity of the lateral cerebellum induces a significant decrease of procedural learning: Interference with the right cerebellar hemisphere activity induces a significant decrease in procedural learning regardless of the hand used to perform the serial reaction time task, whereas left cerebellar hemisphere activity seems more linked with procedural learning through the ipsilateral hand. In conclusion, the present study shows for the first time that a transient interference with the functions of the cerebellar cortex results in an impairment of procedural learning in normal subjects and it provides new evidences for interhemispheric differences in the lateral cerebellum.     

Abnormalities of imaged motor sequences in children with developmental coordination disorder.

The chronometry of real and imagined movements was investigated in a group of children with developmental coordination disorder (DCD) and a group of matched controls. The visually-guided pointing task was used to investigate the speed for accuracy trade-offs that occur as target size is varied for both real and imagined performance. In the control group, the speed for accuracy trade-off for both real and imagined performance conformed to Fitts' law. In the DCD group only real movements conformed to Fitts' law. This pattern of performance suggests that children with DCD have an impairment in the ability to generate internal representations of volitional movements. This may reflect part of a general impairment in the processing of efference copy in DCD.     

Motor skill learning in children with Developmental Coordination Disorder

Children with Developmental Coordination Disorder (DCD) are characterized as having motor difficulties and learning impairment that may last well into adolescence and adulthood. Although behavioral deficits have been identified in many domains such as visuo-spatial processing, kinesthetic perception, and cross-modal sensory integration, recent studies suggested that the functional impairment of certain brain areas, such as cerebellum and basal ganglia, are the underlying causes of DCD. This review focuses on the “motor learning deficits” in DCD and their possible neural correlates. It presents recent evidence from both behavioral and neuroimaging studies and discusses dominant neural hypotheses in DCD. Given the heterogeneity of this disorder, a successful intervention program should target the specific deficits on an individual basis. Future neuroimaging studies are critical steps in enhancing our understanding of learning deficits in DCD.     

Neurocase,Volume 18, Guest reviewers

Abstract

In adults, moving an object using precision grip involves anticipatory adjustment of grip force for fluctuations in inertial load force. These adjustments suggest that motion planning is based on an internal model of the effect or system and the environment. In the current study, we evaluate the coordination of grip force with load force in a child with developmental coordination disorder (DCD) and a matched, normally developing, control child. The children completed five tasks: (i) lifting an object; (ii) moving an object upwards; (iii) moving an object downwards; (iv) holding an object subject to unpredictable perturbation; (v) a time production (tapping) task. A number of differences were observed between the children. In particular, compared to the control, the child with DCD showed an earlier rise in grip force when making both upward and downward movements. We discuss this result in relation to the greater variability in explicit timing and longer reflex delays observed in the child with DCD. We conclude that this paradigm offers insight into the motion planning difficulties seen in DCD, providing a useful new methodology for the investigation of the observed coordination difficulties.     

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.