Utilizing the independent t-test, it was ascertained that during the pre-test stage, no statistically significant differences existed between the two groups concerning age, percentile rank scores of MABC-2, and scores on the DCDQ and PMOQ-T questionnaires (p > 0.05). The findings of the comparison between the two groups in the pre-test stage for selected indicators are succinctly presented in Table 1.
The p-values obtained from the independent t-test for each variable were greater than 0.05, indicating no significant differences between the experimental and control groups at the pre-test stage for the selected indicators.
To investigate the effect of motor imagery training program on action planning in two groups (control and experimental), a repeated measures (2x2) analysis of variance was used with between-subjects factor (group) and within-subjects factor (time) in two pre-test and post-test periods. The results, as shown in Table 2 and Fig. 1, indicated significant main effects of group and time, as well as an interaction effect. Using one-way analysis of variance, it was determined that the two groups did not have a significant difference in the pre-test stage (p = 0.325), but in the post-test stage, the experimental group and control group had a significant difference \(\:F\left(\text{1,35}\right)=21.6;P<0.001)\). Additionally, the control group did not have a significant difference between the pre-test and post-test stages (p=0.13), but the experimental group showed significant improvement compared to the pre-test \(\:t\left(17\right)=-5.65\:;P<0.001)\).
The p-values obtained from the statistical analyses confirm significant differences, indicating that the motor imagery training program had a notable impact on action planning in the experimental group compared to the control group.
Results and conclusion
The objective of this research was to investigate the impact of Motor Imagery (MI) training on action planning in children with Developmental Coordination Disorder (DCD). To achieve this, the effects of motor imagery training, specifically hand rotation (implicit imagery), combined with explicit motor imagery training, on action planning were examined in two experimental and control groups. The results indicated a significant and positive difference in the action planning ability of the experimental group compared to the control group. It is inferred that a combination of explicit and implicit motor imagery exercises enables children with Developmental Coordination Disorder (DCD) to develop and improve their ability to plan actions and create internal models. Overall, considering the obtained results, we conclude that utilizing the strategy of internal modeling through motor imagery exercises in children with DCD has been developed, and the potential of exercises and interventions related to motor imagery can be harnessed to shape internal representations and enhance action planning in children with DCD. The obtained results align with previous studies, including those by Boviro et al. (2019) and Ebrahimi et al. (2020), serving as evidence for the role of motor imagery exercises in the development of internal modeling and action planning. Boviro and colleagues (2019) utilized explicit motor imagery with instructional guidance, while Ebrahimi and colleagues (2020) employed virtual reality exercises for imagery to study action planning in children with DCD. In the current study, a combination of implicit and explicit motor imagery exercises was used to examine action planning. In typically developing children, it has been demonstrated that the effectiveness of motor imagery is associated with a greater tendency to have comfortable end position of action (action planning) 8,34. Therefore, it can be inferred that the improvement in action planning functions in children with DCD, under the influence of motor imagery exercises, is linked to the advancement of motor imagery abilities. This activates the predictive modeling cycle through motor imagery, leading to an increase in the comfort effect at the endpoint of the action in the targeted task. In explaining the role of motor imagery training in the development of motor skills learning and enhancement, one can point to the functional equivalence and correlation between motor imagery and actual motor execution. According to the PETTLEP model (Physical, Environment, Task, Timing, Learning, Emotion, Perspective) introduced by Holmes and colleagues in 2001, motor imagery processes share same physiological neural processes with real movements, offering a plausible explanation for the role of imagery in performance improvement. According to the PETTLEP model, for maximum efficacy, motor imagery should encompass seven components: physical presence, environmental similarity, task similarity, timing similarity, matching learning stages, emotional factors, and perspectiv35.
At the neurocognitive level, motor imagery involves common neural networks (premotor and parietal cortex) with regions related to action planning and execution. Motor imagery essentially means internal simulation of actual movements. Motor imagery possesses functional equivalence at neural (activation of motor areas in the frontal, parietal, and premotor regions), behavioral (speed and accuracy trade-off), physiological (heart rate changes), and computational (predictive modeling of sensory outcomes) levels with real movements (40). Internal predictive modeling is considered a computational unit for precise and fast execution. These models encode the dynamics of body segments in relation to the environment and predict the consequences of voluntary actions. It means that by creating a motor command, a copy of it is sent to the predictive model, which is then used to determine the post-execution body state and sensory consequences of the impending action 35. Considering the relationship between motor imagery and motor planning, the overlap of neural structures associated with these processes, and the enhancement of motor imagery ability through motor imagery instructions, it seems that motor imagery training could be an effective intervention strategy in improving action planning skills in children with DCD. Motor imagery, in addition to aiding skill development, reflects an individual's ability to plan movements and use anticipatory internal models 36. One of the challenges faced by children with DCD in anticipatory control is a reduced ability to mentally visualize a motor action from a first-person perspective 37. The use of motor imagery through a first-person perspective encourages the performer to assess task constraints. This enables them to internally represent appropriate bodily states for the task, facilitating the comfort of end position of the action 8.
Also, an important part of human interactions includes predicting the actions of others, and according to the framework of predictive processing, inferring the intention and purpose of the observed action by minimizing the prediction error occurs at all levels of the cortical hierarchy during the observation and execution of actions. Mirror neuron systems become active both during the execution and observation of actions, playing a crucial role in these processes.
Mirror neuron systems exist in the premotor areas, subcortical motor areas, and the superior parietal gyrus, with reciprocal connections between them.
Engaging in Purposeful activity training leads to neuroplasticity and changes in brain structures, especially in the frontal, premotor, and parietal regions. Neuroplasticity through the mirror neuron system occurs with real observation and execution. In motor imagery training, individuals activate mirror neurons by observing their own and others' actions and by performing the same actions. This leads to the activation of mirror neurons and the formation and strengthening of representational cycles of actions in similar cortical regions38,39. There is an association between perception and action.
Comparing mirror neuron activity in two groups of skilled and novice athletes during observation and prediction tasks indicates greater dysynchronization of mu waves (an index of mirror neuron activity) in skilled individuals compared to novices. It seems that the gaining experience in virtual reality environments and self-observation, compared to the control group, results in the enhanced performance of the mirror neuron system, which is effective in predictive motor control. The experience and expertise of individuals lead to differences in the level of mirror neuron activity. Skilled individuals use their internal and predictive models to recognize environmental information, while novices lack such developed internal models. The experience and expertise of individuals result in differences in the level of mirror neuron activity. Skilled individuals utilize their internal predictive models for recognizing environmental information, while novices lack developed internal models 40. According to motor learning theory, motor learning and retraining take place when accompanied by repetitive exercises and functional activities in various environmental conditions, along with the provision of appropriate feedback.
The improvement in the performance of children with Developmental Coordination Disorder (DCD) resulting from intervention exercises, such as motor imagery exercises, may be attributed to the repetitive nature of the exercises and the availability of multiple feedback sources. Additionally, the observation and imitation of movements contribute to the plasticity of the nervous system through mirror neurons41. In the motor imagery task (mental rotation of the hand) used in this study, which involves directionality and judgment of the stimulus type, the ability to represent the expected action coordinates is necessary. The progress of DCD children in the experimental group in the targeted task indicates an increase in the ability to activate mental representations and internal action. It appears that the specific task training leads to the activation of internal representation cycles, which is effective in predictive modeling.
Although the increase in activity of mirror neurons has been inferred in this study to lead to the activation of internal representations, this inference requires further investigation. Considering that cognitive functions may impact internal modeling, future studies are suggested to examine the effects of motor imagery exercises on executive functions and working memory. Additionally, it is recommended to explore the consolidation, transfer, and application of acquired abilities in the daily activities and motor skills of DCD children through motor imagery training. Therefore, based on the conducted studies that refer to the potential for development of internal modeling functions35,42 and the findings of previous studies 8,36, as well as the present study on the effectiveness of motor imagery training on action planning in DCD children, it seems that we can utilize the high capacity of motor imagery training implicitly and explicitly. Additionally, by employing PETTLEP imagery model extensively and activating the first-person perspective (resulting in greater activation of mirror neurons), we can improve the action planning ability of children with DCD.
It appears that through motor imagery training, DCD children were able to construct and develop motor representations. Alongside actual execution, they utilized visual and tactile information to make accurate predictions of their movements and reduce prospective planning errors.