Neuromodulation : journal of the International Neuromodulation Society
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Randomized Controlled Trial
Resting-State Network Changes Following Transcranial Magnetic Stimulation in Patients With Aphasia-A Randomized Controlled Study.
Although repetitive transcranial magnetic stimulation (rTMS) has exhibited promising efficacy in treating stroke-related aphasia, changes in neuroimaging in response to this therapy remain unclear. ⋯ The Clinicaltrials.gov registration number for the study is NCT03059225.
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Transcranial magnetic stimulation (TMS) has been extensively used for the treatment of depression, obsessive-compulsive disorder, and certain neurologic disorders. Despite having promising treatment efficacy, the fundamental neural mechanisms of TMS remain understudied. ⋯ The Clinicaltrials.gov registration number for the study is NCT03394066.
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The objective of the study was to investigate transcranial wave propagation through two low-intensity focused ultrasound (LIFU)-based brain stimulation techniques-transcranial focused ultrasound stimulation (tFUS) and transcranial pulse stimulation (TPS). Although tFUS involves delivering long trains of acoustic pulses, the newly introduced TPS delivers ultrashort (∼3 μs) pulses repeated at 4 Hz. Accordingly, only a single simulation study with limited geometry currently exists for TPS. We considered a high-resolution three-dimensional (3D) whole human head model in addition to water bath simulations. We anticipate that the results of this study will help researchers investigating LIFU have a better understanding of the effects of the two different techniques. ⋯ This study simulated TPS administration using a 3D realistic image-derived data set. Although our comparison results are strictly limited to the model parameters and assumptions made, we were able to elucidate some clear differences between the two approaches. We hope this initial study will pave the way for systematic comparison between the two approaches in the future.
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Short-interval intracortical inhibition (SICI) is a paired-pulse transcranial magnetic stimulation (TMS) technique that is commonly used to quantify intracortical inhibitory tone in the primary motor cortex. Whereas conventional measures of SICI (C-SICI) quantify inhibition by the amplitude of the motor evoked potential (MEP), alternative measures involving threshold tracked SICI (TT-SICI) instead record the TMS intensity required to maintain a consistent MEP amplitude. Although both C-SICI and TT-SICI are thought to reflect inhibition mediated by γ-aminobutyric acid type A (GABAA) receptors, recent evidence suggests that the mechanisms involved with each measure may not be equivalent. This study aimed to use combined TMS-electroencephalography (TMS-EEG) to investigate the cortical mechanisms contributing to C-SICI and TT-SICI. ⋯ Our findings further demonstrate that C-SICI and TT-SICI likely reflect different facets of GABAA-mediated processes, with inhibition produced by TT-SICI appearing to align more closely with TMS-EEG measures of cortical excitability.
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Cognitive dysfunction (CD) is a commonly reported symptom of major depressive disorder (MDD). Patients with treatment-resistant depression (TRD) tend to experience greater rates of CD; however, treatment options are limited. Repetitive transcranial magnetic stimulation (rTMS) is effective in treating affective symptoms in patients with TRD, but its potential effect on CD in TRD has not been established. ⋯ rTMS may be associated with improvements in verbal memory in patients with TRD who present with global CD and who are clinical responders to the treatment. These findings warrant replication in a larger sample as well as further investigations into the neural mechanisms of cognitive improvement after rTMS.