Feedforward motor control in developmental dyslexia and developmental coordination disorder: Does comorbidity matter?

Area of Science:

• Neuroscience
• Developmental Psychology
• Motor Control Research

Background:

• Predictive motor control relies on internal models, encompassing feedforward and online control.
• Impairments in motor control are suspected in various learning disorders.
• The feedforward component's role in developmental dyslexia (DD) and developmental coordination disorder (DCD) is not fully understood.

Purpose of the Study:

• To investigate the feedforward component of predictive motor control in children with DD and/or DCD.
• To compare motor control abilities between children with specific learning disorders and typically developing (TD) children.

Main Methods:

• A bimanual unloading paradigm was employed.
• Children supported a load with one arm (postural arm) and experienced unexpected or voluntary unloading.
• Kinematics and electromyography of the postural arm were analyzed.

Main Results:

• All children demonstrated anticipatory unloading responses.
• Children with both DD and DCD exhibited delayed inhibition of flexor muscles during voluntary unloading compared to other groups.
• This indicates a specific deficit in the feedforward motor control component for the comorbid DD-DCD group.

Conclusions:

• A deficit in the feedforward component of motor control may be particularly characteristic of comorbid learning disorder subtypes, such as DD-DCD.
• Understanding motor performance deficits in children requires dissociating predictive motor control components and focusing on subtypes and comorbidities.
• This research contributes to a comprehensive framework for motor deficits in children with learning disorders.