Understanding the neural basis of motor development in early childhood

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The acquisition of skilled motor abilities is one of the most important aspects of human development. However, fine motor control and coordination does not approach adult patterns of stability until after the preschool years, a period when many motor disorders also emerge. Little is known about the underlying neural development of motor control, although it is known that both brain structure and function undergo dramatic changes throughout early childhood. Using Magnetoencephalography (MEG) functional measures in preschool children, we have recently demonstrated that movement-related brain activity does not demonstrate adult-like patterns until after preschool age. Studies in non-human primates have demonstrated that the motor cortex and its associated efferent pathways undergo significant changes in neural organization postnatally. This includes the delayed maturation of phylogenetically newer motor pathways originating in posterior motor cortex with direct connections to spinal motor neurons - the corticomotoneuronal (CM) pathways - which are critical for fine motor control such as dexterous hand movements. This suggests that the maturation of this motor system also occurs late in human development, yet such changes have never been directly measured, nor is their impact on normal motor development known. In the proposed research, we will combine for the first time, non-invasive neuroimaging techniques (functional MEG and structural MRI) with kinematic measures of fine motor skill assessments in typically developing children from ages 6 to 10 years to identify and track neurological correlates of critical milestones in motor skill development.  We will use child-friendly motor tasks to obtain high-resolution MEG motor source imaging, combined with MRI tractography of motor pathways, to directly test the hypothesis that the maturation of motor skills with age (e.g., improved dexterity) will be accompanied by a shift to activation of CM neurons during the control of skilled movements. Importantly, we will track these changes longitudinally within individual children at different stages of development, providing neurophysiological indicators of both typical and delayed motor development. We will also use this information to guide computational modeling of the involved cortical motor networks that can predict the observed changes in electrical brain activity to test and validate physiological models of developmental changes in these networks. Our study will be the first to examine structural brain changes over a critical age period in combination with functional MEG measures, and detailed assessments of general and fine motor function in the same group of children. This will provide a new perspective on the postnatal development of motor abilities in typically developing children, laying the groundwork for a better understanding of both typical and atypical motor skill development during early childhood.