The Effects of Transcranial Direct-Current Stimulation on Motor Learning, Motor Maps, and Functional Networks in Children
Date
2022-08
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Abstract
Mapping the structure and function of the motor system in children informs our understanding of brain development, health, and disease. Neuronavigated robotic transcranial magnetic stimulation (TMS) is a state-of-the-art tool that can non-invasively explore primary motor cortex (M1) excitability and generate high-resolution motor maps of upper extremity muscles. However, fundamental studies are lacking in the developing brain. We propose a safe protocol, integrating methods capable of simultaneously exploring M1 modulation and TMS motor maps in typically developing children. Next, we investigated whether behavioural performance corresponds to TMS motor map outcomes and M1-excitability. We generated detailed bilateral motor maps of multiple hand muscles and observed hemispheric-specific relationships between M1-excitability, map outcomes, and motor performance. As most TMS mapping studies have reported variable results, we also determined the reliability of robotic TMS motor maps and specific outcomes across short- and long-term sessions. Our findings suggest that careful interpretation of mapping protocols and outcomes is required to interrogate M1 plasticity. M1 has become a central target to modulate plasticity for its critical role in motor control and learning. Transcranial direct current stimulation (tDCS) can non-invasively modulate M1-excitability in healthy and clinical populations. Primarily studied in adults, tDCS can enhance motor learning when paired with a motor task. However, the effects of tDCS may differ in the developing brain due to anatomical and maturational idiosyncrasies. High-definition tDCS (HD-tDCS) provides more focal targeting of cortical areas, leading to enhanced motor learning in adults, but is yet to be investigated in a pediatric population. Therefore, we aimed to determine the effects of tDCS and HD-tDCS on upper limb motor learning in typically developing children. We demonstrated that both forms of stimulation safely enhanced motor learning with long-term retention of effects. With a pressing need to determine the underlying mechanisms of such neuromodulation, we then applied our TMS mapping methods and advanced functional magnetic resonance imaging (fMRI) techniques to characterize the effects of tDCS-enhanced motor learning on motor network physiology. Alterations in motor maps and both inter-and intra-hemispheric functional motor networks were identified. We have advanced the understanding of motor system developmental and interventional plasticity in children.
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Keywords
Non-invasive Brain Stimulation, Pediatrics, Perinatal Stroke, Transcranial Magnetic Stimulation, Transcranial Direct Current Stimulation, Motor Learning
Citation
Giuffre, A. (2022). The effects of transcranial direct-current stimulation on motor learning, motor maps, and functional networks in children (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.