Brain Stimul
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Cathodal transcranial direct current stimulation (tDCS) of the right frontal cortex improves language abilities in post-stroke aphasic patients. Yet little is known about the effects of right frontal cathodal tDCS on normal language function. ⋯ The results support the notion that the after-effects of tDCS on brain function are at least in part determined by the anatomical and functional connectivity of the targeted region.
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In this study we tested the hypothesis whether a lasting change in the excitability of cortical output circuits can be obtained in healthy humans by combining a peripheral nerve stimulation during a concomitant depolarization and/or hyperpolarization of motor cortex. To reach this aim we combined two different neurophysiological techniques each of them able to induce a lasting increase of cortical excitability by them self: namely median nerve repetitive electrical stimulation (rEPNS) and transcranial direct current stimulation (tDCS). Ten normal young volunteers were enrolled in the present study. ⋯ Anodal or cathodal tDCS + rEPNS and sham tDCS + rEPNS caused a lasting facilitation of H-reflex. These findings suggest that by providing afferent input to the motor cortex while its excitability level is increased or decreased by tDCS may be a highly effective means for inducing an enduring bi-directional plasticity. The mechanism of this protocol may be complex, involving either cortical and spinal after effects.
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Transcranial magnetic stimulation (TMS) of the human primary motor hand area (M1-HAND) can produce multiple descending volleys in fast-conducting corticospinal neurons, especially so-called indirect waves (I-waves) resulting from trans-synaptic excitation. Facilitatory interaction between these I-waves can be studied non-invasively using a paired-pulse paradigm referred to as short-interval intracortical facilitation (SICF). ⋯ SICF elicited using monophasic as well as half-sine pulses is affected by current direction at clearly suprathreshold intensities. The impact of current orientation is stronger for monophasic compared with half-sine pulses. The direction-specific effect of paired-pulse TMS on the strength of early versus late SICF shows that different cortical circuits mediate early and late SICF.
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In Parkinson's disease (PD) dyskinesias appear after long-term dopaminergic treatment. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or the globus pallidus internus (GPi) is a well-established treatment option for both PD symptoms and complications of medication. ⋯ Stimulation of the Pf has a specific impact on dyskinesias, which is similar to that found after EPN stimulation, and which is accompanied by changes of oscillatory activity.
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Case Reports
Effects of pedunculopontine area and pallidal DBS on gait ignition in Parkinson's disease.
Freezing of gait is a disabling feature of Parkinson's disease, and so far no established treatment exists. Deep brain stimulation of the pedunculopontine area has been proposed to treat refractory gait disorders, yet data on measurable effects, especially in combination with stimulation of other targets, are scarce. ⋯ Combined multifocal stimulation may be a promising option for gait ignition and freezing of gait in advanced Parkinson's disease.