Browsing by Author "Giuffre, Adrianna"

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    Effects of Transcranial Direct Current Stimulation on GABA and Glx in Children: A pilot study
    (Public Library of Science (PLoS), 2020-01-07) Nwaroh, Chidera; Giuffre, Adrianna; Cole, Lauran; Bell, Tiffany; Carlson, Helen L.; MacMaster, Frank P.; Kirton, Adam; Harris, Ashley D.
    Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that safely modulates brain excitability and has therapeutic potential for many conditions. Several studies have shown that anodal tDCS of the primary motor cortex (M1) facilitates motor learning and plasticity, but there is little information about the underlying mechanisms. Using magnetic resonance spectroscopy (MRS), it has been shown that tDCS can affect local levels of gamma-aminobutyric acid (GABA) and Glx (a measure of glutamate and glutamine combined) in adults, both of which are known to be associated with skill acquisition and plasticity; however this has yet to be studied in children and adolescents. This study examined GABA and Glx in response to conventional anodal tDCS (a-tDCS) and high definition tDCS (HD-tDCS) targeting the M1 in a pediatric population. Twenty-four typically developing, right-handed children ages 12-18 years participated in five consecutive days of tDCS intervention (sham, a-tDCS or HD-tDCS) targeting the right M1 while training in a fine motor task (Purdue Pegboard Task) with their left hand. Glx and GABA were measured before and after the protocol (at day 5 and 6 weeks) using a PRESS and GABA-edited MEGA-PRESS MRS sequence in the sensorimotor cortices. Glx measured in the left sensorimotor cortex was higher in the HD-tDCS group compared to a-tDCS and sham at 6 weeks (p = 0.001). No changes in GABA were observed in either sensorimotor cortex at any time. These results suggest that neither a-tDCS or HD-tDCS locally affect GABA and Glx in the developing brain and therefore it may demonstrate different responses in adults.
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    The Effects of Transcranial Direct-Current Stimulation on Motor Learning, Motor Maps, and Functional Networks in Children
    (2022-08) Giuffre, Adrianna; Kirton, Adam; Carlson, Helen; Kiss, Zelma; Cluff, Tyler
    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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    Sensorimotor Robotic Measures of tDCS- and HD-tDCS-Enhanced Motor Learning in Children
    (2018-12-18) Cole, Lauran; Dukelow, Sean P.; Giuffre, Adrianna; Nettel-Aguirre, Alberto; Metzler, Megan J.; Kirton, Adam
    Transcranial direct-current stimulation (tDCS) enhances motor learning in adults. We have demonstrated that anodal tDCS and high-definition (HD) tDCS of the motor cortex can enhance motor skill acquisition in children, but behavioral mechanisms remain unknown. Robotics can objectively quantify complex sensorimotor functions to better understand mechanisms of motor learning. We aimed to characterize changes in sensorimotor function induced by tDCS and HD-tDCS paired motor learning in children within an interventional trial. Healthy, right-handed children (12–18 y) were randomized to anodal tDCS, HD-tDCS, or sham targeting the right primary motor cortex during left-hand Purdue pegboard test (PPT) training over five consecutive days. A KINARM robotic protocol quantifying proprioception, kinesthesia, visually guided reaching, and an object hit task was completed at baseline, posttraining, and six weeks later. Effects of the treatment group and training on changes in sensorimotor parameters were explored. Twenty-four children (median 15.5 years, 52% female) completed all measures. Compared to sham, both tDCS and HD-tDCS demonstrated enhanced motor learning with medium effect sizes. At baseline, multiple KINARM measures correlated with PPT performance. Following training, visually guided reaching in all groups was faster and required less corrective movements in the trained arm ((2) = 9.250, ). Aspects of kinesthesia including initial direction error improved across groups with sustained effects at follow-up ((2) = 9.000, ). No changes with training or stimulation were observed for position sense. For the object hit task, the HD-tDCS group moved more quickly with the right hand compared to sham at posttraining ((2) = 6.255, ). Robotics can quantify complex sensorimotor function within neuromodulator motor learning trials in children. Correlations with PPT performance suggest that KINARM metrics can assess motor learning effects. Understanding how tDCS and HD-tDCS enhance motor learning may be improved with robotic outcomes though specific mechanisms remain to be defined. Exploring mechanisms of neuromodulation may advance therapeutic approaches in children with cerebral palsy and other disabilities.