tDCS Anodal tDCS increases bilateral corticospinal excitability irrespective of hemispheric dominance

2020 ◽  
Vol 2 (2) ◽  
pp. 1-17
Author(s):  
Simin Rahman ◽  
Ummutal Siddique ◽  
Ashlyn Frazer ◽  
Alan Pearce ◽  
Dawson Kidgell
Keyword(s):  
Primary Motor Cortex ◽  
Corticospinal Excitability ◽  
Hemispheric Dominance ◽  
Anodal Tdcs ◽  
Medical Practitioners ◽  
Non Invasive ◽  
Design Changes ◽  
Bilateral Effects ◽  
The Brain ◽  
Stimulation Technique

Background: Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that utilizes weak direct currents to induce polarity-dependent modulation of corticospinal excitability. Although tDCS exerts a modulatory effect over the stimulation region, several studies have also demonstrated that distal areas of the brain connected to the region of stimulation may also be affected, as well as the contralateral hemisphere. Objective: We examined the effect of a single session of anodal tDCS on corticospinal excitability and inhibition of both the stimulated and non-stimulated hemisphere and examined the influence of these responses by the brain-derived neurotrophic factor (BDNF) polymorphism. Methods: In a randomized cross-over design, changes in corticospinal excitability and inhibition of the stimulated and non-stimulated hemispheres were analysed in 13 participants in both the dominant and non-dominant primary motor cortex (M1). Participants were exposed to 20 min of anodal and sham tDCS and also undertook a blood sample for BDNF genotyping. Results: TMS revealed a bilateral increase in corticospinal excitability irrespective of which hemisphere (dominant vs non-dominant) was stimulated (all P < 0.05). Furthermore, the induction of corticospinal excitability was influenced by the BDNF polymorphism. Conclusion: This finding shows that anodal tDCS induces bilateral effects in corticospinal excitability irrespective of hemispheric dominance. This finding provides scientists and medical practitioners with a greater understanding as to how this technique may be used as a therapeutic tool for clinical populations. 

scholarly journals Multimodal Assessment of Precentral Anodal TDCS: Individual Rise in Supplementary Motor Activity Scales With Increase in Corticospinal Excitability

2021 ◽  
Vol 15 ◽  
Author(s):  
Anke Ninija Karabanov ◽  
Keiichiro Shindo ◽  
Yuko Shindo ◽  
Estelle Raffin ◽  
Hartwig Roman Siebner
Keyword(s):  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Single Pulse ◽  
Individual Variability ◽  
Corticospinal Excitability ◽  
Anodal Tdcs ◽  
Related Activity ◽  
Whole Brain ◽  
After Effects ◽  
Visuomotor Tracking

BackgroundTranscranial direct current stimulation (TDCS) targeting the primary motor hand area (M1-HAND) may induce lasting shifts in corticospinal excitability, but after-effects show substantial inter-individual variability. Functional magnetic resonance imaging (fMRI) can probe after-effects of TDCS on regional neural activity on a whole-brain level.ObjectiveUsing a double-blinded cross-over design, we investigated whether the individual change in corticospinal excitability after TDCS of M1-HAND is associated with changes in task-related regional activity in cortical motor areas.MethodsSeventeen healthy volunteers (10 women) received 20 min of real (0.75 mA) or sham TDCS on separate days in randomized order. Real and sham TDCS used the classic bipolar set-up with the anode placed over right M1-HAND. Before and after each TDCS session, we recorded motor evoked potentials (MEP) from the relaxed left first dorsal interosseus muscle after single-pulse transcranial magnetic stimulation(TMS) of left M1-HAND and performed whole-brain fMRI at 3 Tesla while participants completed a visuomotor tracking task with their left hand. We also assessed the difference in MEP latency when applying anterior-posterior and latero-medial TMS pulses to the precentral hand knob (AP-LM MEP latency).ResultsReal TDCS had no consistent aftereffects on mean MEP amplitude, task-related activity or motor performance. Individual changes in MEP amplitude, measured directly after real TDCS showed a positive linear relationship with individual changes in task-related activity in the supplementary motor area and AP-LM MEP latency.ConclusionFunctional aftereffects of classical bipolar anodal TDCS of M1-HAND on the motor system vary substantially across individuals. Physiological features upstream from the primary motor cortex may determine how anodal TDCS changes corticospinal excitability.

scholarly journals Pinging the Brain with Transcranial Magnetic Stimulation Reveals Cortical Reactivity in Time and Space

2019 ◽  
Author(s):  
Sangtae Ahn ◽  
Flavio Fröhlich
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Target Location ◽  
Single Pulse ◽  
Corticospinal Excitability ◽  
Mu Rhythm ◽  
Time And Space ◽  
Mechanistic Investigation ◽  
The Brain

AbstractSingle-pulse transcranial magnetic stimulation (TMS) elicits an evoked electroencephalography (EEG) potential (TMS-evoked potential, TEP), which is interpreted as direct evidence of cortical reactivity to TMS. Thus, combining TMS with EEG may enable the mechanistic investigation of how TMS treatment paradigms engage network targets in the brain. However, there remains a central controversy about whether the TEP is a genuine marker of cortical reactivity to TMS or the TEP is contaminated by responses to peripheral somatosensory and auditory inputs. Resolving this controversy is of great significance for the field and will validate TMS as a tool to probe networks of interest in cognitive and clinical neuroscience. Here, we delineated the TEP’s cortical origins by localizing successive TEP components in time and space and modulating them subsequently with transcranial direct current stimulation (tDCS). We collected both motor evoked potentials (MEPs) and TEPs elicited by suprathreshold single-pulse TMS to the left primary motor cortex (M1). We found that the earliest TEP component (P25) was localized on the TMS target location (left M1) and the following TEP components (N45 and P60) largely were localized on the primary somatosensory cortex, which may reflect afferent input by hand-muscle twitches. The later TEP components (N100, P180, and N280) largely were localized to the auditory cortex. To casually test that these components reflect cortical and corticospinal excitability, we applied tDCS to the left M1. As hypothesized, we found that tDCS modulated cortical and corticospinal excitability selectively by modulating the pre-stimulus mu-rhythm oscillatory power. Together, our findings provide causal evidence that the early TEP components reflect cortical reactivity to TMS.

scholarly journals Determination of anodal tDCS intensity threshold for reversal of corticospinal excitability: an investigation for induction of counter-regulatory mechanisms

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Maryam Hassanzahraee ◽  
Michael A. Nitsche ◽  
Maryam Zoghi ◽  
Shapour Jaberzadeh
Keyword(s):  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Single Pulse ◽  
Random Order ◽  
Corticospinal Excitability ◽  
Regulatory Mechanisms ◽  
Anodal Tdcs ◽  
Post Intervention ◽  
Stimulation Intensity ◽  
Intensity Threshold

Abstract Transcranial direct current stimulation is applied to modulate activity, and excitability of the brain. Basically, LTP-like plasticity is induced when anodal tDCS (a-tDCS) is applied over the primary motor cortex. However, it has been shown that specific parameters of a-tDCS can induce a plasticity reversal. We aimed to systematically assess the intensity threshold for reversal of the direction of plasticity induced by a-tDCS, monitored by corticospinal excitability (CSE), and explored mechanisms regulating this reversal. Fifteen healthy participants received a-tDCS in pseudo-random order for 26 min with four intensities of 0.3, 0.7, 1, and 1.5 mA. To measure CSE changes, single-pulse TMS was applied over the left M1, and motor evoked potentials of a contralateral hand muscle were recorded prior to a-tDCS, immediately and 30-min post-intervention. Paired-pulse TMS was used to evaluate intracortical excitation and inhibition. CSE increased significantly following a-tDCS with an intensity of 0.7 mA; however, the expected effect decreased and even reversed at intensities of 1 and 1.5 mA. ICF was significantly increased while SICI and LICI decreased at 0.7 mA. On the other hand, a significant decrease of ICF, but SICI and LICI enhancement was observed at intensities of 1, and 1.5 mA. The present findings show an intensity threshold of ≥ 1 mA for 26 min a-tDCS to reverse LTP- into LTD-like plasticity. It is suggested that increasing stimulation intensity, with constant stimulation duration, activates counter-regulatory mechanisms to prevent excessive brain excitation. Therefore, stimulation intensity and plasticity induced by a-tDCS might non-linearly correlate in scenarios with prolonged stimulation duration.

scholarly journals No effect of tDCS of the primary motor cortex on isometric exercise performance or perceived fatigue

2019 ◽  
Author(s):  
James Graeme Wrightson ◽  
Rosemary Twomey ◽  
Guillaume Y. Millet
Keyword(s):  
Motor Cortex ◽  
Exercise Performance ◽  
Primary Motor Cortex ◽  
Isometric Exercise ◽  
Knee Extension ◽  
Corticospinal Excitability ◽  
Knee Extensors ◽  
Anodal Tdcs ◽  
Isometric Knee Extension ◽  
Before And After

Introduction: Anodal transcranial direct current stimulation (tDCS) of the primary motor cortex has been reported to improve isometric exercise performance without changing corticospinal excitability. One possible cause for this may be the previous use of relatively high (2 mA) current intensities, which have inconsistent effects on corticospinal excitability. The present pre-registered study aimed to replicate previously reported ergogenic effects of 2 mA tDCS, and examine whether 1 mA anodal tDCS both improved isometric exercise performance and perceived fatigue, and more reliably altered corticospinal excitability. Methods: On three separate occasions, participants performed a sustained submaximal isometric knee extension until failure after receiving either 1 mA, 2mA or sham anodal tDCS. Corticospinal excitability of the knee extensors was measured using transcranial magnetic stimulation immediately before and after tDCS. Rating of fatigue was recorded throughout the isometric exercise.Results: Neither 1 nor 2 mA tDCS improved exercise performance, or reduced perceived fatigue, compared to sham stimulation. There was also no effect of tDCS on the corticospinal excitability of the knee extensors.Discussion: We found no effect of tDCS on either exercise performance, perceived fatigue or corticospinal excitability. This study adds to the growing body of literature which has failed to find an ergogenic effect of tDCS. Large preregistered replications of previously reported effects are now required before tDCS can be considered an effective method to improve exercise performance.

NON-INVASIVE BCI METHOD: EEG - ELECTROENCEPHALOGRAPHY

2019 ◽  
pp. 139-145
Author(s):  
Selma Büyükgöze
Keyword(s):  
Brain Computer Interface ◽  
Computer Interface ◽  
Electrode Placement ◽  
Eeg Signals ◽  
Non Invasive ◽  
Brain Signals ◽  
Brain States ◽  
The Brain

Brain Computer Interface consists of hardware and software that convert brain signals into action. It changes the nerves, muscles, and movements they produce with electro-physiological signs. The BCI cannot read the brain and decipher the thought in general. The BCI can only identify and classify specific patterns of activity in ongoing brain signals associated with specific tasks or events. EEG is the most commonly used non-invasive BCI method as it can be obtained easily compared to other methods. In this study; It will be given how EEG signals are obtained from the scalp, with which waves these frequencies are named and in which brain states these waves occur. 10-20 electrode placement plan for EEG to be placed on the scalp will be shown.

scholarly journals Individualization of tDCS intensity according to corticospinal excitability does not improve stimulation efficacy over the primary motor cortex

2021 ◽  
Vol 1 (3) ◽  
pp. 100028
Author(s):  
Etienne Sallard ◽  
Jaimie Lee Rohrbach ◽  
Catherine Brandner ◽  
Nicolas Place ◽  
Jérôme Barral
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Corticospinal Excitability

scholarly journals Cerebellar rTMS and PAS effectively induce cerebellar plasticity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Martje G. Pauly ◽  
Annika Steinmeier ◽  
Christina Bolte ◽  
Feline Hamami ◽  
Elinor Tzvi ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Healthy Subjects ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Premotor Cortex ◽  
Motor Pathways ◽  
Non Invasive ◽  
Cerebellar Plasticity

AbstractNon-invasive brain stimulation techniques including repetitive transcranial magnetic stimulation (rTMS), continuous theta-burst stimulation (cTBS), paired associative stimulation (PAS), and transcranial direct current stimulation (tDCS) have been applied over the cerebellum to induce plasticity and gain insights into the interaction of the cerebellum with neo-cortical structures including the motor cortex. We compared the effects of 1 Hz rTMS, cTBS, PAS and tDCS given over the cerebellum on motor cortical excitability and interactions between the cerebellum and dorsal premotor cortex / primary motor cortex in two within subject designs in healthy controls. In experiment 1, rTMS, cTBS, PAS, and tDCS were applied over the cerebellum in 20 healthy subjects. In experiment 2, rTMS and PAS were compared to sham conditions in another group of 20 healthy subjects. In experiment 1, PAS reduced cortical excitability determined by motor evoked potentials (MEP) amplitudes, whereas rTMS increased motor thresholds and facilitated dorsal premotor-motor and cerebellum-motor cortex interactions. TDCS and cTBS had no significant effects. In experiment 2, MEP amplitudes increased after rTMS and motor thresholds following PAS. Analysis of all participants who received rTMS and PAS showed that MEP amplitudes were reduced after PAS and increased following rTMS. rTMS also caused facilitation of dorsal premotor-motor cortex and cerebellum-motor cortex interactions. In summary, cerebellar 1 Hz rTMS and PAS can effectively induce plasticity in cerebello-(premotor)-motor pathways provided larger samples are studied.

In vivo exploration of brain phosphorus 31 metabolism in patients with senile dementia of Alzheimer type

1994 ◽  
Vol 9 (2) ◽  
pp. 105-109
Author(s):  
G Mecheri ◽  
Y Bissuel ◽  
J Dalery ◽  
JL Terra ◽  
G Balvay ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Senile Dementia ◽  
Phospholipid Metabolism ◽  
Alzheimer Type ◽  
Dementia Of Alzheimer Type ◽  
Non Invasive ◽  
Significant Difference ◽  
The Brain

SummaryIn vivo NMR 31p spectroscopy is a non invasive, non ionizing method of exploration of energy and phospholipid metabolism in the brain. This study consisted of comparing 31p spectra in five patients with Senile Dementia of Alzheimer Type (SDAT) with those of four controls of similar ages. Abnormal phosphonionocsters (PME) concentrations, either high or low, were found in the patients, but statistical analysis did not elicit any significant difference relative to controls.

scholarly journals The brain timewise: how timing shapes and supports brain function

2015 ◽  
Vol 370 (1668) ◽  
pp. 20140170 ◽  
Author(s):  
Riitta Hari ◽  
Lauri Parkkonen
Keyword(s):  
Human Brain ◽  
Brain Imaging ◽  
Brain Function ◽  
Temporal Dynamics ◽  
Generative Models ◽  
Network Activity ◽  
Brain Diseases ◽  
Specific Information ◽  
Non Invasive ◽  
The Brain

We discuss the importance of timing in brain function: how temporal dynamics of the world has left its traces in the brain during evolution and how we can monitor the dynamics of the human brain with non-invasive measurements. Accurate timing is important for the interplay of neurons, neuronal circuitries, brain areas and human individuals. In the human brain, multiple temporal integration windows are hierarchically organized, with temporal scales ranging from microseconds to tens and hundreds of milliseconds for perceptual, motor and cognitive functions, and up to minutes, hours and even months for hormonal and mood changes. Accurate timing is impaired in several brain diseases. From the current repertoire of non-invasive brain imaging methods, only magnetoencephalography (MEG) and scalp electroencephalography (EEG) provide millisecond time-resolution; our focus in this paper is on MEG. Since the introduction of high-density whole-scalp MEG/EEG coverage in the 1990s, the instrumentation has not changed drastically; yet, novel data analyses are advancing the field rapidly by shifting the focus from the mere pinpointing of activity hotspots to seeking stimulus- or task-specific information and to characterizing functional networks. During the next decades, we can expect increased spatial resolution and accuracy of the time-resolved brain imaging and better understanding of brain function, especially its temporal constraints, with the development of novel instrumentation and finer-grained, physiologically inspired generative models of local and network activity. Merging both spatial and temporal information with increasing accuracy and carrying out recordings in naturalistic conditions, including social interaction, will bring much new information about human brain function.

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