Abnormalities of imagined motor sequences in children with developmental coordination disorder (original) (raw)
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The International journal of neuroscience, 2011
Several research studies indicate that children with developmental coordination disorder (DCD) show delays with an array of perceptual-motor skills. One of the explanations, based on limited research, is that these children have problems generating and/or monitoring a mental (action) representation of intended actions, termed the "internal modeling deficit" (IMD) hypothesis. According to the hypothesis, children with DCD have significant limitations in their ability to accurately generate and utilize internal models of motor planning and control. The focus of this review is on one of the methods used to examine action representation-motor imagery, which theorists argue provides a window into the process of action representation (e.g., Jeannerod, 2001 . Neural simulation of action: A unifying mechanism for motor cognition. Neuroimage, 14, 103-109.). Included in the review are performance studies of typically developing and DCD children, and possible brain structures involved.
DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, 2020
DCD 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. The latest edition of the international clinical recommendations of developmental coordination disorder (DCD) were published in 2019. 1 Compared with earlier editions, there has been a noticeable shift in the conceptualization of DCD as a pure motor syndrome to a disorder characterized by more complex motor-cognitive issues. Research has shown deficits across different aspects of motor control and motor learning, as well as cognitive control (executive function). Accordingly, the 2019 guidelines recommended that both motor and non-motor aspects of functioning for an individual child with DCD be considered when setting up an intervention (recommendation 21). In this paper we first provide an overview of current research on motor planning in children with DCD, noting in particular the effect of task demands or complexity on the expression of planning deficits. In the second part we discuss recent evidence on the use of motor imagery and action observation (action observation) for remediation of these motor problems. MOTOR PLANNING AND TASK COMPLEXITY Sound motor planning is important for a wide variety of daily activities, such as picking up and drinking from a cup, opening a door, or navigating through a crowded room. While many such actions have no serious consequences when planning goes awry, other situations can be far more hazardous, such as crossing a busy street. 2 This situation poses a complex planning problem, with cars approaching from left and right at different closing speeds, and in countries like the Netherlands, cyclists crossing unpredictably. In these complex environments it is of utmost importance that planning is performed with great precision and well before the action is initiated. Put simply , proper (motor) planning is essential for the safe and efficient performance of many activities in daily life. In a recent systematic review of experimental research on mechanisms of DCD, Wilson et al. 3 identified sustained growth of work, with a total of 106 studies published between September 2011 and September 2017. On the strength of good methodological quality, the review clearly showed that the expression of motor control deficits was dependent on the nature of the tasks and their complexity. That is, motor problems were most evident under conditions of high task complexity (e.g. dual-tasks, tasks demanding more precision, tasks performed under tight temporal constraints and/or under restricted visual conditions). Moreover, there was converging evidence to support deficits in the predictive control of movements, as poor anticipatory planning was a common denominator in the many studies. Motor control theories state that when an action is planned, the motor parameters related to the action such as trajectory, velocity, force, and required precision are represented as internal or feedforward models. 4,5 Internal models contribute to smooth, efficient, and accurate motor performance, reducing the necessity for the motor system to rely on slower forms of feedback-based control. According to the internal modeling deficit hypothesis, children
Constrained action selection in children with developmental coordination disorder
2008
The effect of advance ('precue') information on short aiming movements was explored in adults, high school children, and primary school children with and without developmental coordination disorder (n= 10, 14, 16, 10, respectively). Reaction times in the DCD group were longer than in the other groups and were more influenced by the extent to which the precue constrained the possible action space. In contrast, reaction time did not alter as a function of precue condition in adults.
Human Movement Science
Children with impaired motor coordination (or Development Coordination Disorder-DCD) have difficulty with the predictive control of movements, evidenced by cross-sectional studies that show impaired motor imagery and action planning abilities. What remains unclear is whether this deficit in predictive control reflects immaturity of the motor system (a developmental delay) or some deviation from normal development (a disorder). To advance this discussion the present study used a longitudinal design to examine the development of motor imagery and action planning in children with DCD. Thirty children were included in the DCD group (aged 6-11 years) and age-and gender-matched to 30 controls. The DCD group had a mABC-2 score ≤ 16th percentile, the control group > 20th percentile. Motor imagery was assessed with the hand rotation task, action planning with a test for end-state comfort. Children participated in three measurements, with one year in between measurements. Results showed that children with DCD were slower and less accurate than their typically developing peers in all subsequent years but were able to improve their motor imagery ability over time. Furthermore, children with DCD showed less planning for ESC at the start of the present study, but were able to catch up with their peers during two-year follow up. These results exemplify that improvement of motor imagery and action planning ability is possible in DCD, and they lend theoretical support to the use of new training techniques that focus on training motor imagery to improve motor skills in children with DCD.