Brain Stimul
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Individuals with communication disorders, such as aphasia, exhibit weak auditory cortex responses to speech sounds and language impairments. Previous studies have demonstrated that pairing vagus nerve stimulation (VNS) with tones or tone trains can enhance both the spectral and temporal processing of sounds in auditory cortex, and can be used to reverse pathological primary auditory cortex (A1) plasticity in a rodent model of chronic tinnitus. ⋯ VNS speech sound pairing provides a novel method to enhance speech sound processing in the central auditory system. Delivery of VNS during speech therapy could improve outcomes in individuals with receptive language deficits.
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Periodic stimulation of occipital areas using transcranial alternating current stimulation (tACS) at alpha (α) frequency (8-12 Hz) enhances electroencephalographic (EEG) α-oscillation long after tACS-offset. Two mechanisms have been suggested to underlie these changes in oscillatory EEG activity: tACS-induced entrainment of brain oscillations and/or tACS-induced changes in oscillatory circuits by spike-timing dependent plasticity. ⋯ Our results indicate that plasticity mechanisms are sufficient to explain α-aftereffects in response to α-tACS, and inform models of tACS-induced plasticity in oscillatory circuits. Modifying brain oscillations with tACS holds promise for clinical applications in disorders involving abnormal neural synchrony.
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Motor training usually increases the excitability of corticospinal outputs to the trained muscles. However, it is uncertain to what extent the change in excitability is a critical component of behavioral learning or whether it is a non-specific side effect. ⋯ The present study indicates that in the short term, increases in corticospinal excitability are not related to immediate changes in behavioral motor outcome.
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Randomized Controlled Trial
Randomized Sham Controlled Double-blind Trial of Repetitive Transcranial Magnetic Stimulation for Adults With Severe Tourette Syndrome.
A small proportion of individuals with Tourette syndrome (TS) have a lifelong course of illness that fails to respond to conventional treatments. Open label studies have suggested that low frequency (1-Hz) repetitive transcranial magnetic stimulation (rTMS) targeting the supplementary motor area (SMA) may be effective in reducing tic severity. ⋯ This RCT did not demonstrate efficacy of 3-week SMA-targeted low frequency rTMS in the treatment of severe adult TS. Further studies using longer or alternative stimulation protocols are warranted.
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Randomized Controlled Trial
Oscillating Square Wave Transcranial Direct Current Stimulation (tDCS) Delivered During Slow Wave Sleep Does Not Improve Declarative Memory More Than Sham: A Randomized Sham Controlled Crossover Study.
A 2006 trial in healthy medical students found that anodal slow oscillating tDCS delivered bi-frontally during slow wave sleep had an enhancing effect in declarative, but not procedural memory. Although there have been supporting animal studies, and similar findings in pathological groups, this study has not been replicated, or refuted, in the intervening years. We therefore tested these earlier results for replication using similar methods with the exception of current waveform (square in our study, nearly sinusoidal in the original). ⋯ In this study, we failed to find improvements in declarative or performance memory and could not replicate an earlier study using nearly identical settings. Specifically we failed to find a beneficial effect on either overnight declarative or non-declarative memory consolidation via square-wave oscillating tDCS intervention applied bi-frontally during early NREM sleep. It is unclear if the morphology of the tDCS pulse is critical in any memory related improvements.