Abstract
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.
Highlights
Developmental coordination disorder (DCD), which is characterized by an inability to perform age-appropriate fine and gross motor skills [1], affects approximately 6% of school-aged children, making it the most common childhood movement disorder [1]
There was a significant correlation between manual dexterity, and delaydetection threshold (DDT) (r = −0.577, p < 0.001), steepness (r = 0.371, p = 0.001) for Experiment-1, error value of the congruent condition for Experiment-2 (r = −0.468, p < 0.001), social communication questionnaire (SCQ) score (r = −0.305, p = 0.010), attention-deficit hyperactivity disorder (ADHD)-RS percentile score (r = −0.325, p = 0.006), and Developmental Coordination Disorder Questionnaire (DCDQ) score (r = 0.356, p = 0.002)
There was a significant correlation between DDT, and steepness (r = −0.435, p < 0.001), error value of the congruent condition (r = 0.461, p < 0.001), error value of the incongruent condition (r = 0.238, p = 0.046), ADHD Rating Scale (ADHD-RS) percentile score (r = 0.329, p = 0.005), and DCDQ score (r = −0.378, p = 0.001)
Summary
Developmental coordination disorder (DCD), which is characterized by an inability to perform age-appropriate fine (hand writing and shoelace tying) and gross motor skills (playing sport and getting dressed) [1], affects approximately 6% of school-aged children, making it the most common childhood movement disorder [1]. Such a broad range of deficits impacts performance of daily tasks, and contributes to secondary long-term health consequences, including reduced engagement in physical activity and social activities [2, 3], and increased risk of low self-esteem, anxiety, and depression [3, 4]. We evaluated the internal model deficit [6,7,8,9] and mirror-neuron system (MNS) deficit [10, 11], i.e., two putative pathophysiological mechanisms thought to impede fine motor skills in DCD, affecting manual dexterity
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