Name: stimulation location determination using a 3d digitizer with high-definition transcranial direct current stimulation
Uploaded: 2019-12-20T13:00:00
Description: Watch this Scientific Journal Video about Stimulation Location Determination using a 3D Digitizer with High-Definition Transcranial Direct Current Stimulation at JoVE.com

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 <strong class="x...

<ol>
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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, ...

This method uses a 10-10 system to overcome the limitations of transcranial direct current stimulation electrode placement, improving the accuracy and reproducibility of the method. The main advantages of this technique are its low cost, simple application and portability. This method is suitable for use with other techniques, for example, functional near-infrared spectroscopy, to verify the location of specific brain regions of interest.This technique is very simple if you are familiar with the proportional requirement of the 10-10 system. Demonstrating the procedure will be Chenyu Lv, a graduate student. To prepare an electrode holding cap, place a swimming cap on headform and measure the distance between the nasion and inion.To localize the vertex, use a skin marker to mark the midpoint of the distance between the nasion and the inion, and measure the distance between the preauricular points. Mark the midpoint of the preauricular points. The point at which both midpoints intersect is the vertex.According to the 10-10 system, find the CP6 and P6, and mark the appropriate midpoint at which these points intersect, called the right temporoparietal junction on the scalp. Then adjust the radius of the four return electrodes, based on the objectives. And mark the center and return electrode locations on the cap.To obtain a 3D digitizer measurement, use a metal scanner to confirm that the environment for 3D digitization is metal-free. Place the swim cap on the subject's head, and using the reference marks on the cap to align the cap with the international 10-10 system for scalp location. When the cap is in place, use a USB interface to connect the 3D digitizer to the computer, and confirm the digitizer software is available and ready.Place the source in front of the subject and fasten the elastic rope of the sensor around the subject's head. In the digitizer software, confirm that the 3D digitizer system is communicating with the software, and use the stylus, and a 10 centimeter ruler length, to record the zero and ten graduations to confirm the accuracy of the stylus. In the software, display the distance between the two recording points.Then collect the position data of the reference points, center electrodes, and the four return electrodes. To cater to the requirement of the functional near-infrared spectroscopy experiments, select and save the transmitter detector and channel options. To initiate the stimulation, install fully charged batteries into the device, and connect the conventional transcranial direct current stimulation device and the four by one stimulation adapter.Connect the cables of the five silver-silver chloride centered ring electrodes to the matching receivers on the four by one adapter output cable. And measure the head of the subject. Place the plastic device cap onto the subject's head, and embed the five plastic high-definition casings in the swimming cap.Locate the vertex FPZ and OZ of the subject, and adjust the reference on the cap to align with the international 10-10 system for scalp locations. When the cap is in place, use the 3D digitizer to collect the position data of the stimulated brain areas. Next, use the end of a plastic syringe to carefully separate the hair through the opening of the plastic casing, until the scalp is exposed, and cover the exposed skin with the electrically conductive gel.On the device, turn on the four by one multi-channel stimulation adapter and set the quality value. Confirm that the default setting is set to scan, and press the mode select button. Switch from the scan to pass and press the polarity button to select, either center anode or cathode.Adjust the settings on the conventional transcranial direct current stimulation device to include the stimulus duration, intensity and sham condition setting and push the relax lever to switch to full current. Once everything has been set, press the start button to initiate the stimulation. The D.C.intensity will ramp up until the target current is reached, and the timer will then show the remaining time.At the end of the stimulation, turn the lever slowly to adjust the current to zero before turning off the power. Open the plastic cap, remove the silver or silver chloride sintered ring electrodes from the casing and remove the swimming cap. Then clean the instruments and provide the subject with materials with which to clean their hair.Using the near infrared spectroscopy statistical parametric mapping standalone registration function, the spatial registration function generates MNI coordinates. To reduce measurement errors, the average value of three data points from the final MNI coordinates of the five electrodes were calculated. In Broadman areas, the anatomical label and its number are obtained.The number after each line indicates the percentage of overlap. In anatomical automatic labels, the anatomical label and percentage of overlap are obtained. For the Broadman areas and anatomical automatic labels, the value represents a percentage of overlap with the cerebral cortex.It is important to make sure that neither the source nor the sensor moves during the 3D digitizer measurement. This procedure can be used for of thought localizations or for any other localizations needed to study the function of the brain. This technique can also be used in personalized brain stimulation for precise positioning.

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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 ...

Transcranial Direct Current Stimulation (tDCS) in Mice

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 ...