This study was supported by the National Natural Science Foundation of China (31972906), Entrepreneurship and Innovation Program for Chongqing Overseas Returned Scholars (cx2017049), Fundamental Research Funds for Central Universities (SWU1809003), Open Research Fund of the Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences (KLMH2019K05), Research Innovation Projects of Graduate Student in Chongqing (CYS19117), and the Research Program Funds of the Collaborative Innovation Center of Assessment toward Basic Education Quality at Beijing Normal University (2016-06-014-BZK01, SCSM-2016A2-15003, and JCXQ-C-LA-1). We would like to thank Prof. Ofir Turel for his suggestions on the early draft of this manuscript.

The protocol meets the guidelines of the Institutional Review Board of Southwest University.
1. Determination of Stimulation Location
<ol>
	<li>Review the literature and confirm the stimulation location (here, the rTPJ)19,20,21.</li>
</ol>
2. Preparation of Electrode Holding Cap
NOTE: The following steps are shown in Figure 1.
<ol>
	<li>Ensure that all necessary materials are readily available: the 3D digitizer (Figure 2), standard measurement tape, a marking pen, the headform, and a swimming cap.</li>
	<li>Put the cap on the headform and mark the points on the cap.
	<ol>
		<li>Localize the Vertex (Cz). To do so, first mark the midpoint of the distance between the nasion and inion using a skin marker13,14,22. Then, measure the distance between the pre-auricular points and mark the midpoint. The point at which both points intersect is the Cz.</li>
		<li>Check the location of the center electrode and the return electrodes. Here, the stimulation was applied on rTPJ. The rTPJ roughly corresponds to the midpoint between CP6 and P6 in the 10-10 EEG system19,20,21.</li>
		<li>Find CP6 and P622,23,24,25. According to the proportional requirements of the 10-10 system, locate the approximate location of the rTPJ on the scalp and mark it on the cap.</li>
		<li>Adjust the radius of the four return electrodes based on the objectives11,14,26. After this decision, mark the center electrode and return electrode locations on the cap.</li>
	</ol>
	</li>
</ol>
3. 3D Digitizer Measurement
<ol>
	<li>Scan with the metal scanner to ensure that the environment for 3D digitizer is metal-free.</li>
	<li>Placement of the cap on the subject&#39;s head
	<ol>
		<li>Make sure that the references (Cz, Fpz, Oz, left preauricular point, and right preauricular point) on the cap align with the international 10-10 system for scalp location22. For example, localize the Vertex (Cz) on the scalp and place the cap onto the subject&#39;s head, aligning the cap&#39;s Cz to the subjects.</li>
	</ol>
	</li>
	<li>Arranging the 3D digitizer equipment
	<ol>
		<li>Connect the 3D digitizer to the computer using the Universal Serial Bus (USB) interface and make sure that the digitizer software is available and ready27.</li>
		<li>Put the source in front of the subject and fasten the elastic rope of the sensor around the head. Importantly, make sure that neither the source nor sensor moves during 3D digitizer measurement. 
		NOTE: The source is a magnetic transmitter that emits an electromagnetic dipole field. The sensor is a receiver that detects the field.</li>
		<li>Open the digitizer software on the computer and make sure that the 3D digitizer system communicates with the software.</li>
		<li>Test the accuracy of the stylus. Find a length of 10 cm on the ruler and record the zero graduation and ten graduation, respectively, using the stylus. 
		NOTE: The measurement distance between the two recording points of the 3D digitizer should be captured. Compare the error with the reading from the 3D tracker.</li>
		<li>Select the New icon and create a new subject file. Select the Sessions box, then Reference. 
		NOTE: Using the 3D digitizer stylus, the reference position data (Cz, inion, nasion, left ear, right ear) of the subject are collected according to the software prompts.</li>
		<li>To cater to the requirement of fNIRS experiments, use the Transmitter, Detector, and Channel options. Collect the position data of the center electrode and four return electrodes 3x for the transmitter, detector, and channel, in order to reduce error. Ensure that five electrodes are numbered and localize in turn.</li>
		<li>Save the three files that are generated.</li>
	</ol>
	</li>
</ol>
4. Data Conversion and Spatial Registration
<ol>
	<li>Select the three files into the NIRS-SPM to achieve the real coordinates registration into MNI space28. Affine transform the reference points and five electrode points in participants to the corresponding points in each entry according to the MRI database in MNI space.</li>
	<li>Register the data to anatomical automatic labels and Brodmann areas and register the spatial information of the five electrode points to both of these.</li>
	<li>Compare the coordinates of stimulation in previous research with the obtained coordinates20,29.</li>
	<li>Make a small cut aligned to the five points marked on the cap, such that the plastic casing is embedded snugly into the cap.</li>
</ol>
5. Stimulation
<ol>
	<li>Make sure that participant have no contraindications (i.e., history of neurological or psychiatric disorders) for HD-tDCS1,3 and that they provided written informed consent prior to the study (including HD-tDCS stimulation).</li>
	<li>For device installation, ensure that all the necessary materials are available (Figure 3). Install the device as detailed in published literature14. A brief description is provided below.
	<ol>
		<li>Install the batteries and check that they are charged.</li>
		<li>Connect the conventional tDCS and 4x1 Stimulation Adapter.</li>
		<li>Connect the cables of five Ag/AgCI sintered ring electrodes to the matching receivers on the 4x1 adapter output cable.</li>
		<li>Check that all materials are connected correctly.</li>
	</ol>
	</li>
	<li>Measure the head of the participant and place the cap on the head.
	<ol>
		<li>Embed the five plastic HD casings in the swimming cap.</li>
		<li>Localize the Cz, Fpz, and Oz of the subject13,14. Adjust the reference on the cap to align with the international 10-10 system for scalp locations22. Once the cap is in position, ensure that it does not move.</li>
		<li>Collect the position data of the stimulated brain areas using the 3D digitizer. Make the corresponding adjustments according to the generated data.</li>
	</ol>
	</li>
	<li>Cover the scalp surface with electrically conductive gel. First, carefully separate the hair through the opening of the plastic casing using the end of a plastic syringe, until the scalp is exposed. Then, cover the exposed scalp with the electrically conductive gel through the plastic casing opening on the scalp surface.</li>
	<li>Set the parameters of the tDCS device: quality value, stimulus duration, intensity, and condition setting.
	<ol>
		<li>Turn on the 4x1 Multichannel Stimulation Adapter.</li>
		<li>Ensure that the default setting is SCAN, which shows the impedance of one electrode at a time in the display window by scanning the electrodes14,30,31. Here, the impedance is described as &#34;quality value&#34;. Values below 1.5 indicate sufficient quality14,30,31. In this case, the values were lower than 1. 
		NOTE: If the impedance value exceeds these required limits, open the cap of the plastic casing with high impedance and adjust the hair and electrode to obtain the desired impedance value.</li>
		<li>Press the &#34;MODE SELECT&#34; button and switch from &#34;SCAN&#34; to &#34;PASS&#34;, after the impedance values are acceptable.</li>
		<li>Select the center-anode or center-cathode by pressing the &#34;POLARITY&#34; button. &#34;CENTRAL ANODE&#34; is the default setting.</li>
		<li>Adjust the settings on the conventional tDCS device to include stimulus duration (min), intensity (mA) and sham condition setting. In this case, anodal active stimulation was 1.5 mA, and the stimulus lasted 20 min. Next, push the &#34;RELAX&#34; lever to switch to full current.</li>
		<li>Once everything is set, initiate the stimulation. Press the &#34;START&#34; button, and the DC intensity will ramp up until the target current is reached. The timer will then show the remaining time. 
		NOTE: Some participants may feel uncomfortable during periods of increased DC intensity. In such cases, the current may be moderately decreased slightly for a few seconds by pulling down the &#34;RELAX&#34; lever. Then, push the dolly bar to full current, gradually, when participants feel comfortable again.</li>
	</ol>
	</li>
</ol>
6. Post-stimulation
<ol>
	<li>When the stimulation is over, turn the lever slowly to adjust the current to zero before turning off the power. Otherwise, participants may perceive stinging sensation or dizziness when turning off the power directly.</li>
	<li>After the stimulation, open the plastic cap and remove the Ag/AgCI sintered ring electrodes from the casing.</li>
	<li>Remove the swimming cap and clean the materials. Provide participants with tools to clean their hair.</li>
	<li>Ask participants to fill out a questionnaire after each stimulation session, if necessary (e.g., to measure adverse effects of screening following HD-tDCS, participant tolerance to brain stimulation, etc.; see Supplementary File).</li>
</ol>

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The authors have nothing to disclose.

Compared to traditional tDCS, HD-tDCS increases the focality of stimulation. Typical sites of stimulation are often based on the 10-20 EEG system. However, determining the precise stimulation points beyond this system can be difficult. This paper combines a 3D digitizer with HD-tDCS to determine stimulation points beyond the 10-20 system. It is important to clearly define the steps and precautions for making and using the electrode cap in such cases.
In general, the position of target stimulat...

Transcranial direct current stimulation (tDCS) is a noninvasive technique that modulates cortical excitability with weak direct currents over the scalp. It aims to establish causality between neural excitability and behavior in healthy humans1,2,3. In addition, as a motor neurorehabilitation tool, tDCS is widely used in the treatment of Parkinson's disease, stroke, and cerebral palsy4. Existing evidence suggests that traditional pad-based tDCS produces current flow through a relatively larger brain region5,6,7. High-definition transcranial direct current stimulation (HD-tDCS), with the center ring electrode sitting over a target cortical region surrounded by four return electrodes8,9, increases focality by circumscribing four ring areas5,10. In addition, changes in excitability of the brain induced by HD-tDCS have significantly larger magnitudes and longer durations than those generated by traditional tDCS7,11. Therefore, HD-tDCS is widely used in research7,11.
Noninvasive brain stimulation (NIBS) requires specialized methods to ensure that a stimulation site is present in the standard MNI and Talairach systems12. Neuronavigation is a technique that allows for mapping interactions between transcranial stimuli and the human brain. Its visualization and 3D image data are used for precise stimulation. In both tDCS and HD-tDCS, a common assessment of stimulation sites on the scalp is typically the EEG 10-20 system13,14. This measurement is widely used for placing the tDCS pads and optode holders for functional near infrared spectroscopy (fNIRS) in the initial stage13,14,15.
Determining the precise stimulation points when using the 10-20 system can be difficult (e.g., in the temporo-parietal junction [TPJ]). The best way to solve this is to obtain structural images from participants using magnetic resonance imaging (MRI), then obtain the exact probe position by matching target points to their structural images using digitizing products15. MRI provides good spatial resolution but is expensive to use15,16,17. Moreover, some participants (e.g., those with metal implants, claustrophobic people, pregnant women, etc.) cannot be subjected to MRI scanners. Therefore, there is a strong need for a convenient and efficient way to overcome the abovementioned limitations and increase accuracy in determining stimulation points.
This protocol uses a 3D digitizer to overcome these limitations. Compared to MRI, key advantages of a 3D digitizer are low costs, simple application, and portability. It combines five reference points (i.e., Cz, Fpz, Oz, left preauricular point, and right preauricular point) of individuals with location information of the target stimulation points. Then, it produces a 3D position of electrodes on the subject's head and estimates their cortical positions by fitting with the vast data from the structural image12,15. This probabilistic registration method enables the presentation of transcranial mapping data in the MNI coordinate system without recording a subject's magnetic resonance images. The approach generates anatomical automatic labels and Brodmann areas11.
The 3D digitizer, used to mark space coordinates based on the data from structural images, was first used to determine the position of optodes in fNIRS research18. For those who use HD-tDCS, a 3D digitizer breaks the finite stimulation points of the EEG 10-20 system. The distance of the four return electrodes and center electrode is flexible and can be adjusted as needed. When using the 3D digitizer with this protocol, the coordinates of the rTPJ were obtained, which is beyond the 10-20 system. Also shown are the procedures for targeting and stimulating the right temporo-parietal junction (rTPJ) of the human brain.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1X1 Low Intensity transcranial DC Stimulator</td>
			<td>Soterix Medical</td>
			<td>1300A</td>
			<td></td>
		</tr>
		<tr>
			<td>3-dimensional Polhemus-Patriot Digitizer</td>
			<td>POLHEMUS</td>
			<td>1A0453-001</td>
			<td>PATRIOT system component</td>
		</tr>
		<tr>
			<td>4X1 Multi-Channel Stimulation Interface</td>
			<td>Soterix Medical</td>
			<td>4X1-C3</td>
			<td></td>
		</tr>
		<tr>
			<td>Dell desktop computer</td>
			<td>Dell</td>
			<td>CRFC4J2</td>
			<td>Master computer to run 3D digitizer application</td>
		</tr>
	</tbody>
</table>

stimulation location determination using a 3d digitizer with high-definition transcranial direct current stimulation

The abundance of neuroimaging data and rapid development of machine learning has made it possible to investigate brain activation patterns. However, causal evidence of brain area activation leading to a behavior is often left missing. Transcranial direct current stimulation (tDCS), which can temporarily alter brain cortical excitability and activity, is a noninvasive neurophysiological tool used to study causal relationships in the human brain. High-definition transcranial direct current stimulation (HD-tDCS) is a noninvasive brain stimulation (NIBS) technique that produces a more focal current compared to conventional tDCS. Traditionally, the stimulation location has been roughly determined through the 10-20 EEG system, because determining precise stimulation points can be difficult. This protocol uses a 3D digitizer with HD-tDCS to increase accuracy in determination of stimulation points. The method is demonstrated using a 3D digitizer for more accurate localization of stimulation points in the right temporo-parietal junction (rTPJ).

Using the methods presented, coordinates of the rTPJ were determined, which requires stimulation points beyond the 10-20 system. First, the circumference of the headform should be similar to the actual head. Here, the length of the nasion to inion of the headform was ~36 cm, and the length between the bilateral preauricular was ~37 cm.
The steps for producing the electrode cap guide the measuring positions of the 10-20 system. Here, Nz, Iz, Cz, Fpz, Oz, Pz, T8, T7, C4, P8, O2, P4, C6, P6, and ...

Watch this Scientific Journal Video about Stimulation Location Determination using a 3D Digitizer with High-Definition Transcranial Direct Current Stimulation at JoVE.com

Stimulation Location Determination using a 3D Digitizer with High-Definition Transcranial Direct Current Stimulation

Presented here is a protocol to achieve higher accuracy in determination of stimulation location combining a 3D digitizer with high-definition transcranial direct current stimulation.

The abundance of neuroimaging data and rapid development of machine learning has made it possible to investigate brain activation patterns. However, ...

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6.7K Views.  Southwest University. Presented here is a protocol to achieve higher accuracy in determination of stimulation location combining a 3D digitizer with high-definition transcranial direct current stimulation.

Video: Stimulation Location Determination using a 3D Digitizer with High-Definition Transcranial Direct Current Stimulation

Combining Transcranial Magnetic Stimulation and fMRI to Examine the Default Mode Network

The default mode network is a group of brain regions that are active when an individual is not focused on the outside world and the brain is at "wakeful rest."1,2,3 It is thought the default mode network corresponds to self-referential or "internal mentation".2,3
It has been hypothesized that, in humans, activity within the default mode network is correlated with certain pathologies (for instance, hyper-activation has been linked to schizophrenia 4,5,6 and autism spectrum disorders 7 whilst hypo-activation of the network has been linked to Alzheimer's and other neurodegenerative diseases 8). As such, noninvasive modulation of this network may represent a potential therapeutic intervention for a number of neurological and psychiatric pathologies linked to abnormal network activation. One possible tool to effect this modulation is Transcranial Magnetic Stimulation: a non-invasive neurostimulatory and neuromodulatory technique that can transiently or lastingly modulate cortical excitability (either increasing or decreasing it) via the application of localized magnetic field pulses.9
In order to explore the default mode network's propensity towards and tolerance of modulation, we will be combining TMS (to the left inferior parietal lobe) with functional magnetic resonance imaging (fMRI). Through this article, we will examine the protocol and considerations necessary to successfully combine these two neuroscientific tools.

In this article, we examine the methodology and considerations relevant to the combination of TMS and fMRI to examine the effects of brain stimulation on the default network.

The default mode network is a group of brain regions that are active when an individual is not focused on the outside world and the brain is at "wakeful ...

TMS: Using the Theta-Burst Protocol to Explore Mechanism of Plasticity in Individuals with Fragile X Syndrome and Autism

Fragile X Syndrome (FXS), also known as Martin-Bell Syndrome, is a genetic abnormality found on the X chromosome.1,2 Individuals suffering from FXS display abnormalities in the expression of FMR1 - a protein required for typical, healthy neural development.3 Recent data has suggested that the loss of this protein can cause the cortex to be hyperexcitable thereby affecting overall patterns of neural plasticity.4,5
In addition, Fragile X shows a strong comorbidity with autism: in fact, 30% of children with FXS are diagnosed with autism, and 2 - 5% of autistic children suffer from FXS.6
Transcranial Magnetic Stimulation (a non-invasive neurostimulatory and neuromodulatory technique that can transiently or lastingly modulate cortical excitability via the application of localized magnetic field pulses 7,8) represents a unique method of exploring plasticity and the manifestations of FXS within affected individuals. More specifically, Theta-Burst Stimulation (TBS), a specific stimulatory protocol shown to modulate cortical plasticity for a duration up to 30 minutes after stimulation cessation in healthy populations, has already proven an efficacious tool in the exploration of abnormal plasticity.9,10 
Recent studies have shown the effects of TBS last considerably longer in individuals on the autistic spectrum - up to 90 minutes.11 This extended effect-duration suggests an underlying abnormality in the brain's natural plasticity state in autistic individuals - similar to the hyperexcitability induced by Fragile X Syndrome.
In this experiment, utilizing single-pulse motor-evoked potentials (MEPs) as our benchmark, we will explore the effects of both intermittent and continuous TBS on cortical plasticity in individuals suffering from FXS and individuals on the Autistic Spectrum.

In this article, we examine the effects of Theta-Burst TMS stimulation on cortical plasticity in individuals suffering from Fragile X syndrome and individuals on the autistic spectrum.

Fragile X Syndrome (FXS), also known as Martin-Bell Syndrome, is a genetic abnormality found on the X chromosome.1,2 Individuals suffering from FXS ...

The NeuroStar TMS Device: Conducting the FDA Approved Protocol for Treatment of Depression

The Neuronetics NeuroStar Transcranial Magnetic Stimulation (TMS) System is a class II medical device that produces brief duration, pulsed magnetic fields. These rapidly alternating fields induce electrical currents within localized, targeted regions of the cortex which are associated with various physiological and functional brain changes.1,2,3
In 2007, O'Reardon et al., utilizing the NeuroStar device, published the results of an industry-sponsored, multisite, randomized, sham-stimulation controlled clinical trial in which 301 patients with major depression, who had previously failed to respond to at least one adequate antidepressant treatment trial, underwent either active or sham TMS over the left dorsolateral prefrontal cortex (DLPFC). The patients, who were medication-free at the time of the study, received TMS five times per week over 4-6 weeks.4
The results demonstrated that a sub-population of patients (those who were relatively less resistant to medication, having failed not more than two good pharmacologic trials) showed a statistically significant improvement on the Montgomery-Asberg Depression Scale (MADRS), the Hamilton Depression Rating Scale (HAMD), and various other outcome measures. In October 2008, supported by these and other similar results5,6,7, Neuronetics obtained the first and only Food and Drug Administration (FDA) approval for the clinical treatment of a specific form of medication-refractory depression using a TMS Therapy device (FDA approval K061053).
In this paper, we will explore the specified FDA approved NeuroStar depression treatment protocol (to be administered only under prescription and by a licensed medical profession in either an in- or outpatient setting).

In this article, we examine the methodology and considerations relevant to the FDA approved depression treatment protocol using the Neuronetics NeuroStar TMS device.

The Neuronetics NeuroStar Transcranial Magnetic Stimulation (TMS) System is a class II medical device that produces brief duration, pulsed magnetic ...

Electrode Positioning and Montage in Transcranial Direct Current Stimulation

Transcranial direct current stimulation (tDCS) is a technique that has been intensively investigated in the past decade as this method offers a non-invasive and safe alternative to change cortical excitability2. The effects of one session of tDCS can last for several minutes, and its effects depend on polarity of stimulation, such as that cathodal stimulation induces a decrease in cortical excitability, and anodal stimulation induces an increase in cortical excitability that may last beyond the duration of stimulation6. These effects have been explored in cognitive neuroscience and also clinically in a variety of neuropsychiatric disorders &#x2013; especially when applied over several consecutive sessions4. One area that has been attracting attention of neuroscientists and clinicians is the use of tDCS for modulation of pain-related neural networks3,5. Modulation of two main cortical areas in pain research has been explored: primary motor cortex and dorsolateral prefrontal cortex7. Due to the critical role of electrode montage, in this article, we show different alternatives for electrode placement for tDCS clinical trials on pain; discussing advantages and disadvantages of each method of stimulation.

Transcranial direct current stimulation (tDCS) is an established technique to modulate cortical excitability1,2. It has been used as an investigative tool in neuroscience due to its effects on cortical plasticity, easy operation, and safe profile. One area that tDCS has been showing encouraging results is pain alleviation 3-5.

Transcranial direct current stimulation (tDCS) is a technique that has been intensively investigated in the past decade as this method offers a ...

Effects of Transcranial Alternating Current Stimulation on the Primary Motor Cortex by Online Combined Approach with Transcranial Magnetic Stimulation

Transcranial Alternating Current Stimulation (tACS) is a neuromodulatory technique able to act through sinusoidal electrical waveforms in a specific frequency and in turn modulate ongoing cortical oscillatory activity. This neurotool allows the establishment of a causal link between endogenous oscillatory activity and behavior. Most of the tACS studies have shown online effects of tACS. However, little is known about the underlying action mechanisms of this technique because of the AC-induced artifacts on Electroencephalography (EEG) signals. Here we show a unique approach to investigate online physiological frequency-specific effects of tACS of the primary motor cortex (M1) by using single pulse Transcranial Magnetic Stimulation (TMS) to probe cortical excitability changes. In our setup, the TMS coil is placed over the tACS electrode while Motor Evoked Potentials (MEPs) are collected to test the effects of the ongoing M1-tACS. So far, this approach has mainly been used to study the visual and motor systems. However, the current tACS-TMS setup can pave the way for future investigations of cognitive functions. Therefore, we provide a step-by-step manual and video guidelines for the procedure.

Transcranial Alternating Current Stimulation (tACS) allows the modulation of cortical excitability in a frequency-specific fashion. Here we show a unique approach which combines online tACS with single pulse Transcranial Magnetic Stimulation (TMS) in order to "probe" cortical excitability by means of Motor Evoked Potentials.

Transcranial Alternating Current Stimulation (tACS) is a neuromodulatory technique able to act through sinusoidal electrical waveforms in a specific ...

Remotely Supervised Transcranial Direct Current Stimulation: An Update on Safety and Tolerability

The remotely supervised tDCS (RS-tDCS) protocol enables participation from home through guided and monitored self-administration of tDCS treatment while maintaining clinical standards. The current consensus regarding the efficacy of tDCS is that multiple treatment sessions are needed to observe targeted behavioral reductions in symptom burden. However, the requirement for patients to travel to clinic daily for stimulation sessions presents a major obstacle for potential participants, due to work or family obligations or limited ability to travel. This study presents a protocol that directly overcomes these obstacles by eliminating the need to travel to clinic for daily sessions.
This is an updated protocol for remotely supervised self-administration of tDCS for daily treatment sessions paired with a program of computer-based cognitive training for use in clinical trials. Participants only need to attend clinic twice, for a baseline and study-end visit. At baseline, participants are trained and provided with a study stimulation device, and a small laptop computer. Participants then complete the remainder of their stimulation sessions at home while they are monitored via videoconferencing software.
Participants complete computerized cognitive remediation during stimulation sessions, which may serve a therapeutic role or as a &#34;placeholder&#34; for other computer-based activity. Computers are enabled for real-time monitoring and remote control by study staff.
Outcome measures that assess feasibility and tolerance are administered remotely with the aid of visual analogue scales that are presented onscreen. Following completion of all RS-tDCS sessions, participants return to clinic for a study end visit in which all study equipment is returned.
Results support the safety, feasibility, and scalability of the RS-tDCS protocol for use in clinical trials. Across 46 patients, 748 RS-tDCS sessions have been completed. This protocol serves as a model for use in future clinical trials involving tDCS.

This manuscript provides an updated remote supervision protocol that enables participation in transcranial direct current stimulation (tDCS) clinical trials while receiving treatment sessions from home. The protocol has been successfully piloted in both patients with multiple sclerosis and Parkinson&#39;s disease.

The remotely supervised tDCS (RS-tDCS) protocol enables participation from home through guided and monitored self-administration of tDCS treatment while ...

Transcranial Electrical Brain Stimulation in Alert Rodents

Transcranial electrical brain stimulation can modulate cortical excitability and plasticity in humans and rodents. The most common form of stimulation in humans is transcranial direct current stimulation (tDCS). Less frequently, transcranial alternating current stimulation (tACS) or transcranial random noise stimulation (tRNS), a specific form of tACS using an electrical current applied randomly within a pre-defined frequency range, is used. The increase of noninvasive electrical brain stimulation research in humans, both for experimental and clinical purposes, has yielded an increased need for basic, mechanistic, safety studies in animals. This article describes a model for transcranial electrical brain stimulation (tES) through the intact skull targeting the motor system in alert rodents. The protocol provides step-by-step instructions for the surgical set-up of a permanent epicranial electrode socket combined with an implanted counter electrode on the chest. By placing a stimulation electrode into the epicranial socket, different electrical stimulation types, comparable to tDCS, tACS, and tRNS in humans, can be delivered. Moreover, the practical steps for tES in alert rodents are introduced. The applied current density, stimulation duration, and stimulation type may be chosen depending on the experimental needs. The caveats, advantages, and disadvantages of this set-up are discussed, as well as safety and tolerability aspects.

This protocol describes a surgical set-up for a permanent epicranial electrode socket and an implanted chest electrode in rodents. By placing a second electrode into the socket, different types of transcranial electrical brain stimulation can be delivered to the motor system in alert animals through the intact skull.

Transcranial electrical brain stimulation can modulate cortical excitability and plasticity in humans and rodents. The most common form of stimulation in ...

Online Transcranial Magnetic Stimulation Protocol for Measuring Cortical Physiology Associated with Response Inhibition

We describe the development of a reproducible, child-friendly motor response inhibition task suitable for online Transcranial Magnetic Stimulation (TMS) characterization of primary motor cortex (M1) excitability and inhibition. Motor response inhibition prevents unwanted actions and is abnormal in several neuropsychiatric conditions. TMS is a non-invasive technology that can quantify M1 excitability and inhibition using single- and paired-pulse protocols and can be precisely timed to study cortical physiology with high temporal resolution. We modified the original Slater-Hammel (S-H) stop signal task to create a &#34;racecar&#34; version with TMS pulses time-locked to intra-trial events. This task is self-paced, with each trial initiating after a button push to move the racecar towards the 800 ms target. GO trials require a finger-lift to stop the racecar just before this target. Interspersed randomly are STOP trials (25%) during which the dynamically adjusted stop signal prompts subjects to prevent finger-lift. For GO trials, TMS pulses were delivered at 650 ms after trial onset; whereas, for STOP trials, the TMS pulses occurred 150 ms after the stop signal. The timings of the TMS pulses were decided based on electroencephalography (EEG) studies showing event-related changes in these time ranges during stop signal tasks. This task was studied in 3 blocks at two study sites (n=38) and we recorded behavioral performance and event-related motor-evoked potentials (MEP). Regression modelling was used to analyze MEP amplitudes using age as a covariate with multiple independent variables (sex, study site, block, TMS pulse condition [single- vs. paired-pulse], trial condition [GO, successful STOP, failed STOP]). The analysis showed that TMS pulse condition (p&#60;0.0001) and its interaction with trial condition (p=0.009) were significant. Future applications for this online S-H/TMS paradigm include the addition of simultaneous EEG acquisition to measure TMS-evoked EEG potentials. A potential limitation is that in children, the TMS pulse sound could&#160;affect behavioral task performance.

We describe an experimental procedure to quantify excitability and inhibition of primary motor cortex during a motor response inhibition task by using Transcranial Magnetic Stimulation throughout the course of a Stop Signal Task.

We describe the development of a reproducible, child-friendly motor response inhibition task suitable for online Transcranial Magnetic Stimulation (TMS) ...

The Combined Use of Transcranial Direct Current Stimulation and Robotic Therapy for the Upper Limb

Neurologic disorders such as stroke and cerebral palsy are leading causes of long-term disability and can lead to severe incapacity and restriction of daily activities due to lower and upper limb impairments. Intensive physical and occupational therapy are still considered main treatments, but new adjunct therapies to standard rehabilitation that may optimize functional outcomes are being studied.
Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that polarizes underlying brain regions through the application of weak direct currents through electrodes on the scalp, modulating cortical excitability. Increased interest in this technique can be attributed to its low cost, ease of use, and effects on human neural plasticity. Recent research has been performed to determine the clinical potential of tDCS in diverse conditions such as depression, Parkinson&#39;s disease, and motor rehabilitation after stroke. tDCS helps enhance brain plasticity and seems to be a promising technique in rehabilitation programs.
A number of robotic devices have been developed to assist in the rehabilitation of upper limb function after stroke. The rehabilitation of motor deficits is often a long process requiring multidisciplinary approaches for a patient to achieve maximum independence. These devices do not intend to replace manual rehabilitation therapy; instead, they were designed as an additional tool to rehabilitation programs, allowing immediate perception of results and tracking of improvements, thus helping patients to stay motivated.
Both tDSC and robot-assisted therapy are promising add-ons to stroke rehabilitation and target the modulation of brain plasticity, with several reports describing their use to be associated with conventional therapy and the improvement of therapeutic outcomes. However, more recently, some small clinical trials have been developed that describe the associated use of tDCS and robot-assisted therapy in stroke rehabilitation. In this article, we describe the combined methods used in our institute for improving motor performance after stroke.

The combined use of transcranial direct current stimulation and robotic therapy as an add-on for conventional rehabilitation therapy may result in improved therapeutic outcomes due to modulation of brain plasticity. In this article, we describe the combined methods used in our institute for improving motor performance after stroke.

Neurologic disorders such as stroke and cerebral palsy are leading causes of long-term disability and can lead to severe incapacity and restriction of ...

Transcranial Direct Current Stimulation (tDCS) in Mice

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique proposed as an alternative or complementary treatment for several neuropsychiatric diseases. The biological effects of tDCS are not fully understood, which is in part explained due to the difficulty in obtaining human brain tissue. This protocol describes a tDCS mouse model that uses a chronically implanted electrode allowing the study of the long-lasting biological effects of tDCS. In this experimental model, tDCS changes the cortical gene expression and offers a prominent contribution to the understanding of the rationale for its therapeutic use.

Transcranial Direct Current Stimulation tDCS in Mice

Transcranial direct current stimulation (tDCS) is a therapeutic technique proposed to treat psychiatric diseases. An animal model is essential for understanding the specific biological alterations evoked by tDCS. This protocol describes a tDCS mouse model that uses a chronically implanted electrode.

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique proposed as an alternative or complementary treatment for ...