Transcranial direct current stimulation effects on I-wave activity in humans

2011 ◽  
Vol 105 (6) ◽  
pp. 2802-2810 ◽  
Author(s):  
Nicolas Lang ◽  
Michael A. Nitsche ◽  
Michele Dileone ◽  
Paolo Mazzone ◽  
Javier De Andrés-Arés ◽  
...  

Transcranial direct current stimulation (tDCS) of the human cerebral cortex modulates cortical excitability noninvasively in a polarity-specific manner: anodal tDCS leads to lasting facilitation and cathodal tDCS to inhibition of motor cortex excitability. To further elucidate the underlying physiological mechanisms, we recorded corticospinal volleys evoked by single-pulse transcranial magnetic stimulation of the primary motor cortex before and after a 5-min period of anodal or cathodal tDCS in eight conscious patients who had electrodes implanted in the cervical epidural space for the control of pain. The effects of anodal tDCS were evaluated in six subjects and the effects of cathodal tDCS in five subjects. Three subjects were studied with both polarities. Anodal tDCS increased the excitability of cortical circuits generating I waves in the corticospinal system, including the earliest wave (I1 wave), whereas cathodal tDCS suppressed later I waves. The motor evoked potential (MEP) amplitude changes immediately following tDCS periods were in agreement with the effects produced on intracortical circuitry. The results deliver additional evidence that tDCS changes the excitability of cortical neurons.

Author(s):  
Vincent Cabibel ◽  
Makii Muthalib ◽  
Jérôme Froger ◽  
Stéphane Perrey

Repeated transcranial magnetic stimulation (rTMS) is a well-known clinical neuromodulation technique, but transcranial direct-current stimulation (tDCS) is rapidly growing interest for neurorehabilitation applications. Both methods (contralesional hemisphere inhibitory low-frequency: LF-rTMS or lesional hemisphere excitatory anodal: a-tDCS) have been employed to modify the interhemispheric imbalance following stroke. The aim of this pilot study was to compare aHD-tDCS (anodal high-definition tDCS) of the left M1 (2 mA, 20 min) and LF-rTMS of the right M1 (1 Hz, 20 min) to enhance excitability and reduce inhibition of the left primary motor cortex (M1) in five healthy subjects. Single-pulse TMS was used to elicit resting and active (low level muscle contraction, 5% of maximal electromyographic signal) motor-evoked potentials (MEPs) and cortical silent periods (CSPs) from the right and left extensor carpi radialis muscles at Baseline, immediately and 20 min (Post-Stim-20) after the end of each stimulation protocol. LF-rTMS or aHD-tDCS significantly increased right M1 resting and active MEP amplitude at Post-Stim-20 without any CSP modulation and with no difference between methods. In conclusion, this pilot study reported unexpected M1 excitability changes, which most likely stems from variability, which is a major concern in the field to consider.


Author(s):  
Fernanda Lobo Rezende ◽  
Natália De Almeida Carvalho Duarte ◽  
Luanda André Collange Grecco ◽  
Claudia Santos Oliveira

Introduction: Transcranial direct current stimulation (tDCS) is a promising technique that stimulates the cortex with a direct, low-intensity electric current and can potentiate motor learning. Objective: Describe the results of an intervention protocol involving anodal stimulation over the primary motor cortex combined with treadmill training in a child with cerebral palsy. Method: The intervention was comprised of ten sessions of anodal tDCS (1mA) over the primary motor cortex during the treadmill training. Stabilometric analysis was evaluated one week before and one week after the intervention. Results: A reduction in oscillations of the COP was found under both conditions (eyes opened and eyes closed. Conclusion: Our findings suggest that anodal tDCS over primary motor cortex can potentiate the results of treadmill training.


2021 ◽  
Author(s):  
Marcela Tengler Carvalho Takahashi ◽  
Paulo Rodrigo Bázan ◽  
Joana Bisol Balardin ◽  
Danielle de Sá Boasquevisque ◽  
Edson Amaro Júnior ◽  
...  

Background: There is limited information about effects of transcranial Direct Current Stimulation(tDCS), delivered within the first weeks post-stroke, on performance of the paretic upper limb and on connectivity between motor areas in the affected and unaffected hemispheres. Objectives: We compared changes in Fugl-Meyer Assessment of Motor Recovery(FMA) scores, connectivity between the primary motor cortex of the unaffected(M1UH) and the affected hemisphere(M1AH), as well as between M1UH and the premotor cortex of the unaffected hemisphere(PMUH) before and after 6 sessions of cathodal tDCS targeting the primary motor cortex of the unaffected hemisphere(M1UH) early after stroke in 13 patients. Methods: This hypothesis-generating substudy was a randomized parallel, two-arm, double-blind, sham-controlled clinical trial performed at the Albert Einstein Hospital. Subjects were randomized active(N=6) or sham(N=7) groups. Results: Clinically relevant differences in FMA scores(≥ 9 points) were observed more often in the sham than in the active group. Between-group differences in changes in FMA scores were not statistically significant(Mann-Whitney test, p=0.133) but the effect size was -0.619(rank biserial correlation). Connectivity measures(Fisher’s z- transform of ROI-to-ROI correlations) between M1AH-M1UH increased in 5/6 participants in the active, and in 2/7 in the sham group after treatment. Between-group differences in changes in connectivity(M1UH-M1AH or PMUH-M1AH) were not statistically significant. In contrast with M1AH-M1UH connectivity, improvements in motor performance were more frequent in the active than in the sham group. Conclusions: Effects of cathodal tDCS on motor performance and on Resting-state Functional Magnetic Resonance Imaging may have distinct underpinnings in subjects at an early stage after stroke.


Cephalalgia ◽  
2011 ◽  
Vol 31 (6) ◽  
pp. 661-670 ◽  
Author(s):  
Niels Hansen ◽  
Mark Obermann ◽  
Franziska Poitz ◽  
Dagny Holle ◽  
Hans-Christoph Diener ◽  
...  

Objective: The study was conducted to investigate the after-effect of transcranial direct current stimulation (tDCS) applied over the human primary motor cortex (M1) on trigeminal and extracranial nociceptive processing. Basic procedures: Nineteen healthy volunteers were stimulated using cathodal, anodal (both 1 mA) or sham tDCS for 20 minutes. Pain processing was assessed by recording trigeminal and extracranial pain-related evoked potentials (PREPs) following electrical stimulation of the contralateral forehead and hand at baseline, 0, 20 and 50 minutes post-tDCS. Main findings: Cathodal tDCS resulted in decreased peak-to-peak amplitudes (PPAs) by 18% while anodal tDCS lead to increased PPAs of PREPs by 35% ( p < .05). Principal conclusions: The decreased PPAs suggest an inhibition and the increased PPAs of PREPs suggest an excitation of trigeminal and extracranial pain processing induced by tDCS of the M1. These results may provide evidence for the effectiveness of tDCS as a therapeutic instrument in treating headache disorders.


2016 ◽  
Vol 44 (5) ◽  
pp. 2184-2190 ◽  
Author(s):  
Sara Tremblay ◽  
Félix Larochelle-Brunet ◽  
Louis-Philippe Lafleur ◽  
Sofia El Mouderrib ◽  
Jean-François Lepage ◽  
...  

2015 ◽  
Vol 41 (6) ◽  
pp. 845-855 ◽  
Author(s):  
Guadalupe Nathzidy Rivera-Urbina ◽  
Giorgi Batsikadze ◽  
Andrés Molero-Chamizo ◽  
Walter Paulus ◽  
Min-Fang Kuo ◽  
...  

2019 ◽  
Vol 30 (5) ◽  
pp. 2972-2985 ◽  
Author(s):  
Saviana Antonella Barbati ◽  
Sara Cocco ◽  
Valentina Longo ◽  
Matteo Spinelli ◽  
Katia Gironi ◽  
...  

Abstract Consistent body of evidence shows that transcranial direct-current stimulation (tDCS) over the primary motor cortex (M1) facilitates motor learning and promotes recovery after stroke. However, the knowledge of molecular mechanisms behind tDCS effects needs to be deepened for a more rational use of this technique in clinical settings. Here we characterized the effects of anodal tDCS of M1, focusing on its impact on glutamatergic synaptic transmission and plasticity. Mice subjected to tDCS displayed increased long-term potentiation (LTP) and enhanced basal synaptic transmission at layer II/III horizontal connections. They performed better than sham-stimulated mice in the single-pellet reaching task and exhibited increased forelimb strength. Dendritic spine density of layer II/III pyramidal neurons was also increased by tDCS. At molecular level, tDCS enhanced: 1) BDNF expression, 2) phosphorylation of CREB, CaMKII, and GluA1, and 3) S-nitrosylation of GluA1 and HDAC2. Blockade of nitric oxide synthesis by L-NAME prevented the tDCS-induced enhancement of GluA1 phosphorylation at Ser831 and BDNF levels, as well as of miniature excitatory postsynaptic current (mEPSC) frequency, LTP and reaching performance. Collectively, these findings demonstrate that anodal tDCS engages plasticity mechanisms in the M1 and highlight a role for nitric oxide (NO) as a novel mediator of tDCS effects.


2009 ◽  
Vol 297 (6) ◽  
pp. G1035-G1040 ◽  
Author(s):  
Samantha Jefferson ◽  
Satish Mistry ◽  
Salil Singh ◽  
John Rothwell ◽  
Shaheen Hamdy

Transcranial direct current stimulation (tDCS) is a novel intervention that can modulate brain excitability in health and disease; however, little is known about its effects on bilaterally innervated systems such as pharyngeal motor cortex. Here, we assess the effects of differing doses of tDCS on the physiology of healthy human pharyngeal motor cortex as a prelude to designing a therapeutic intervention in dysphagic patients. Healthy subjects ( n = 17) underwent seven regimens of tDCS (anodal 10 min 1 mA, cathodal 10 min 1 mA, anodal 10 min 1.5 mA, cathodal 10 min 1.5 mA, anodal 20 min 1 mA, cathodal 20 min 1 mA, Sham) on separate days, in a double blind randomized order. Bihemispheric motor evoked potential (MEP) responses to single-pulse transcranial magnetic stimulation (TMS) as well as intracortical facilitation (ICF) and inhibition (ICI) were recorded using a swallowed pharyngeal catheter before and up to 60 min following the tDCS. Compared with sham, both 10 min 1.5 mA and 20 min 1 mA anodal stimulation induced increases in cortical excitability in the stimulated hemisphere (+44 ± 17% and +59 ± 16%, respectively; P < 0.005) whereas only 10 min 1.5 mA cathodal stimulation induced inhibition (−26 ± 4%, P = 0.02). There were neither contralateral hemisphere changes nor any evidence for ICI or ICF in driving the ipsilateral effects. In conclusion, anodal tDCS can alter pharyngeal motor cortex excitability in an intensity-dependent manner, with little evidence for transcallosal spread. Anodal stimulation may therefore provide a useful means of stimulating pharyngeal cortex and promoting recovery in dysphagic patients.


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