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Background Perinatal stroke causes lifelong motor disability, affecting independence and quality of life. Non-invasive neuromodulation interventions such as transcranial direct current stimulation (tDCS) combined with intensive therapy may improve motor function in adult stroke hemiparesis but is under-explored in children. Measuring cortical metabolites with proton magnetic resonance spectroscopy (MRS) can inform cortical neurobiology in perinatal stroke but how these change with neuromodulation is yet to be explored. Methods A double-blind, sham-controlled, randomized clinical trial tested whether tDCS could enhance intensive motor learning therapy in hemiparetic children. Ten days of customized, goal-directed therapy was paired with cathodal tDCS over contralesional primary motor cortex (M1, 20 min, 1.0 mA, 0.04 mA/cm 2 ) or sham. Motor outcomes were assessed using validated measures. Neuronal metabolites in both M1s were measured before and after intervention using fMRI-guided short-echo 3T MRS. Results Fifteen children [age(range) = 12.1(6.6–18.3) years] were studied. Motor performance improved in both groups and tDCS was associated with greater goal achievement. After cathodal tDCS, the non-lesioned M1 showed decreases in glutamate/glutamine and creatine while no metabolite changes occurred with sham tDCS. Lesioned M1 metabolite concentrations did not change post-intervention. Baseline function was highly correlated with lesioned M1 metabolite concentrations ( N -acetyl-aspartate, choline, creatine, glutamate/glutamine). These correlations consistently increased in strength following intervention. Metabolite changes were not correlated with motor function change. Baseline lesioned M1 creatine and choline levels were associated with clinical response. Conclusions MRS metabolite levels and changes may reflect mechanisms of tDCS-related M1 plasticity and response biomarkers in hemiparetic children with perinatal stroke undergoing intensive neurorehabilitation. [ABSTRACT FROM AUTHOR]

Introduction Mild traumatic brain injury (mTBI) outcomes are variable, and 10–15% may suffer from prolonged symptoms beyond 3 months that impair the child's return to normal activities. Neurophysiological mechanisms of mTBI are incompletely understood, particularly in children, but alterations in cortical excitability have been proposed to underlie post-concussion syndrome. Improved understanding is required to advance interventions and improve outcomes. Objective/Hypothesis To determine if cortical excitability is altered in children with mTBI, and its association with clinical symptoms. Methods This was a cross-sectional controlled cohort study. School-aged children (8–18 years) with mTBI were compared to healthy controls. Cortical excitability was measured using multiple TMS paradigms in children with (symptomatic) and without (recovered) persistent symptoms one-month post-injury. Primary outcome was the cortical silent period (cSP), a potential neurophysiological biomarker of GABAergic inhibition. Secondary outcomes included additional TMS neurophysiology, safety and tolerability. Associations between neurophysiology parameters and clinical symptoms were evaluated. Results Fifty-three children with mTBI (55% male; mean age 14.1 SD: 2.4 years; 35 symptomatic and 27 asymptomatic participants) and 28 controls (46% male; mean age 14.3 SD: 3.1 years) were enrolled. cSP duration was similar between groups (F (2, 73) = 0.55, p = 0.582). Log 10 long interval intracortical inhibition (LICI) was reduced in symptomatic participants compared to healthy controls (F (2, 59) = 3.83, p = 0.027). Procedures were well tolerated with no serious adverse events. Conclusions TMS measures of cortical excitability are altered at one month in children with mTBI. Long interval cortical inhibition is decreased in children who remain symptomatic at one month post-injury. [ABSTRACT FROM AUTHOR]

• Application of anodal tDCS concurrent to surgical training enhances unimanual skill acquisition compared to training alone. • Changes in delta EEG activity in the sensorimotor network are associated with surgical skill improvement. • EEG patterns of unimanual and bimanual surgical skill performance differ, primarily within the parietal cortex. • Anodal tDCS modulated alpha frequency band activity during bimanual surgical skill performance. Transcranial direct-current stimulation (tDCS), an increasingly applied form of non-invasive brain stimulation, can augment the acquisition of motor skills. Motor learning investigations of tDCS are limited to simple skills, where mechanisms are increasingly understood. Investigations of meaningful, complex motor skills possessed by humans, such as surgical skills, are limited. This replication and extension of our previous findings used electroencephalography (EEG) to determine how tDCS and complex surgical training alters electrical activity in the sensorimotor network to enhance complex surgical skill acquisition. In twenty-two participants, EEG was recorded during baseline performance of simulation-based laparoscopic surgical skills. Participants were randomized to receive 20 min of primary motor cortex targeting anodal tDCS or sham concurrent to 1 h of surgical skill training. EEG was reassessed following training, during a post-training repetition of the surgical tasks. Our results replicated our previous study suggesting that compared to sham, anodal tDCS enhanced the acquisition of unimanual surgical skill. Surgical training modulated delta frequency band activity in sensorimotor regions. Next, the performance of unimanual and bimanual skills evoked unique EEG profiles, primarily within the beta frequency-band in parietal regions. Finally, tDCS-paired surgical training independently modulated delta and alpha frequency-bands in sensorimotor regions. Application of tDCS during surgical skill training is feasible, safe and tolerable. In conclusion, we are the first to explore electrical brain activity during performance of surgical skills, how electrical activity may change during surgical training and how tDCS alters the brain to enhance skill acquisition. The results provide preliminary evidence of neural markers that can be targeted by neuromodulation to optimize complex surgical training. [ABSTRACT FROM AUTHOR]

Background Recent changes in surgical training environments may have limited opportunities for trainees to gain proficiency in skill. Complex skills such as neurosurgery require extended periods of training. Methods to enhance surgical training are required to overcome duty-hour restrictions, to ensure the acquisition of skill proficiency. Transcranial direct-current stimulation (tDCS) can enhance motor skill learning, but is untested in surgical procedural training. We aimed to determine the effects of tDCS on simulation-based neurosurgical skill acquisition. Methods Medical students were trained to acquire tumor resection skills using a virtual reality neurosurgical simulator. The primary outcome of change in tumor resection was scored at baseline, over 8 repetitions, post-training, and again at 6 weeks. Participants received anodal tDCS or sham over the primary motor cortex. Secondary outcomes included changes in brain resected, resection effectiveness, duration of excessive forces (EF) applied, and resection efficiency. Additional outcomes included tDCS tolerability. Results Twenty-two students consented to participate, with no dropouts over the course of the trial. Participants receiving tDCS intervention increased the amount of tumor resected, increased the effectiveness of resection, reduced the duration of EF applied, and improved resection efficiency. Little or no decay was observed at 6 weeks in both groups. No adverse events were documented, and sensation severity did not differ between stimulation groups. Conclusions The addition of tDCS to neurosurgical training may enhance skill acquisition in a simulation-based environment. Trials of additional skills in high-skill residents, and translation to nonsimulated performance are needed to determine the potential utility of tDCS in surgical training. [ABSTRACT FROM AUTHOR]