Brain Stimul
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Transcranial magnetic stimulation (TMS) is commonly used to measure the effects of stroke on corticomotor excitability, intracortical function, and interhemispheric interactions. The interhemispheric inhibition model posits that recovery of motor function after stroke is linked to rebalancing of asymmetric interhemispheric inhibition and corticomotor excitability. This model forms the rationale for using neuromodulation techniques to suppress unaffected motor cortex excitability, and facilitate affected motor cortex excitability. However, the evidence base for using neuromodulation techniques to promote post-stroke motor recovery is inconclusive. ⋯ The neurophysiological effects of stroke are primarily localised to the affected hemisphere, and there is no clear evidence for hyper-excitability of the unaffected hemisphere or imbalanced interhemispheric inhibition. This indicates that facilitating affected M1 excitability directly may be more beneficial than suppressing unaffected M1 excitability for promoting post-stroke recovery.
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Randomized Controlled Trial
Stimulating cognition in schizophrenia: A controlled pilot study of the effects of prefrontal transcranial direct current stimulation upon memory and learning.
Schizophrenia is characterized by prominent cognitive deficits, impacting on memory and learning; these are strongly associated with the prefrontal cortex. ⋯ This is the first study to show a significant longer-term effect of tDCS on working memory in schizophrenia. Given the current lack of effective therapies for cognitive deficits, tDCS may offer an important novel approach to modulating brain networks to ameliorate cognitive deficits in schizophrenia.
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Randomized Controlled Trial
Cortical excitability after pediatric mild traumatic brain injury.
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. ⋯ 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.
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Continuous theta burst stimulation (cTBS) and intermittent TBS (iTBS) are powerful patterns of repetitive transcranial magnetic stimulation (rTMS), with substantial potential for motor function rehabilitation post-stroke. However, TBS of suprahyoid motor cortex excitability has not been investigated. This study investigated TBS effects on suprahyoid motor cortex excitability and its potential mechanisms in healthy subjects. ⋯ TBS effectively regulates suprahyoid motor cortex excitability. Suppression of excitability in one hemisphere leads to further activation of the corresponding contralateral motor cortex. iTBS reverses the inhibitory effect induced by cTBS of the contralateral suprahyoid motor cortex.
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Long-interval intracortical inhibition (LICI) is a transcranial magnetic stimulation (TMS) paradigm that uses paired magnetic stimuli separated by 100-200 ms to investigate the activity of cortical GABAergic interneurons. While commonly applied, the mechanisms contributing to LICI are not well understood, and growing evidence suggests that inhibition observed at different interstimulus intervals (ISI) may involve non-identical processes. ⋯ These findings suggest that LICI100 and LICI150 reflect complex measurements of cortical inhibition with differential contributions from comparable circuits.