Name: Online Repetitive Transcranial Magnetic Stimulation of Dorsomedial and Dorsolateral Prefrontal Cortex in Cognition Decision Making, and Cognitive Dissonance (Video) | JoVE Journal
Uploaded: 2025-12-05T12:30:00.000+00:00
Duration: 13 min 20 s
Description: Learn precise rTMS targeting of dorsolateral and dorsomedial prefrontal cortex using neuronavigation and robotic systems during cognitive tasks. This method enhances stimulation accuracy for cognitive neuroscience research.

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5 minutes

The article was prepared with the support of the Russian Science Foundation grant &#8470; 24-18-00432, https://rscf.ru/project/24-18-00432 and has been carried out using the HSE Automated System of non-invasive brain stimulation with the possibility of synchronous registration of brain activity and registration of eye movements.

All procedures were approved by the local research ethics committee of the Higher School of Economics (HSE), Moscow, with consent from all participants.
1. Participant recruitment
NOTE: Participants are required to report no history of implanted metallic devices, neurological disorders, or psychiatric conditions. TMS is administered in accordance with the most recent safety recommendations. Prior to participation, all individuals must be thoroughly informed about the nature of the study and provide written informed consent. An entire set of equipment needed to run the online repetitive TMS protocol utilizing neuronavigation and robotic systems for precise targeting of dorsolateral and dorsomedial prefrontal cortices during an experimental procedure was shown (Table of Materials).
<ol>
	<li>Check in the preliminary questionnaire and in the informed consent that participants are right-handed, have no metal, neuro- or cardio stimulators in their head or body, have no hearing problems and migraines, have never had any head traumas, are not pregnant, do not take psychotropic or antihistamine medications, have never had brain or spinal cord surgery and their relatives are not diagnosed with epilepsy.</li>
	<li>If participants indicate that they have ever fainted, check that these cases were related solely to physiological reasons. Besides, participants should be informed not to take alcohol or drugs one day before the experiment and not to take coffee or any products and drinks containing caffeine four hours before the start of the experiment.</li>
</ol>
2. Coil and robotic arm calibration
NOTE: Coil calibration is performed using the calibration plate, whereas the robotic arm does not need any additional equipment to be calibrated. All of them have silver reference balls, which allow the camera to recognize objects in space.
<ol>
	<li>Align the calibration plate with the coil, set the scale on both the calibration plate and coil, and calibrate using the software.</li>
	<li>Calibrate the robotic arm force sensor using the associated software. Press the robotic arm surface with different force levels to prevent hard pressure on the participant&#39;s head but ensure a snug fit to the head during stimulation.</li>
</ol>
3. Preparation of the individual MRI scans
NOTE: A major part of the navigation system preparation is preparing the system for individual MRI scans for the patient registration procedure. This can be done even before a participant comes. The main goal is to match the individual brain coordinates with the coordinates in universal coordinate systems, such as MNI and Talairach.
<ol>
	<li>First, make a 3D model of the participant&#39;s head using software associated with the TMS system.</li>
	<li>Perform the Talairach registration and alignment procedure.
	<ol>
		<li>Align each subject&#39;s brain to a standardized brain coordinate system based on anatomical landmarks from the Talairach atlas. Manually identify and set 3 benchmarks, namely, the anterior commissure, posterior commissure, and falx cerebri, based on the Talairach atlas.</li>
		<li>Identify the anterior commissure as a small circular or oval structure located anterior to the third ventricle and inferior to the rostrum of the corpus callosum on mid-sagittal MRI slices and as a hyperintense dot anterior to the third ventricle on axial slices.</li>
		<li>Identify the posterior commissure on mid-sagittal MRI slices as a horizontally oriented structure situated just above the cerebral aqueduct and posterior to the third ventricle. For the falx cerebri select the MRI slice that exhibits maximal bilateral symmetry of deep brain structures and mark it on the interhemispheric fissure.</li>
	</ol>
	</li>
	<li>Adjust the Talairach space grid to the size of the 3D model of the head. The Talairach space will be generated with standardized coordinates not dependent on individual brain differences.</li>
	<li>Set the targets of the future stimulation and the required rotation angle according to the predefined MNI coordinates of the study.</li>
	<li>Calculate entries for the targets as their corresponding locations on the surface of the participant&#39;s head to position the robotic arm during the stimulation. 
	NOTE: In this experiment, entries for the vertex control point were manually defined. For marking the vertex target, mark the point located at the intersection of the mid-sagittal and coronal planes that pass through the nasion&#8211;inion and interaural line, respectively; or take the vertex coordinates in normalized MNI or Talairach space from prior literature and map the normalized point into the individual MRI space. Software automatically calculates the location in the individual MRI space through affine transformation matrices.</li>
	<li>For more accurate tracking of the participant&#39;s head location, set MRI landmarks on the 3D model of the participant&#39;s head. For this study, landmarks on the left and right ears and the nasion were used, but any other landmarks can be used based on convenience.</li>
</ol>
4. Patient registration
NOTE: The patient registration procedure is done when the participant arrives.
<ol>
	<li>Provide the consent forms, required information about the experiment, and earplugs for protecting the participant&#39;s hearing.</li>
	<li>Place the reference tracker on the participant&#39;s head. Ensure that it is attached to the participant&#39;s head at a point where the robotic arm will not occasionally touch the tracker during the stimulation. 
	NOTE: The tracker consists of three silver reflective reference balls that are identified by the navigation system to localize the coordinates of the participant&#39;s head during the procedure and the experiment. Conventionally, the tracker is placed on the forehead. However, to be sure that the entry targets of the dlPFC and dmPFC are available for the navigation system and can be reached by the robotic arm, the tracker was placed between the forehead and the right ear (it can be placed near the left ear as well depending on the leading reference plate of the robotic arm).</li>
	<li>Fix the reference tracker on the participant&#39;s head with the elastic belt tightly enough, but ensure it is comfortable for the participant. 
	NOTE: The belt fixation is flexible depending on the participant&#39;s head size. The belt was moved down to the forehead area, bent down, and fixed to provide better access to the dmPFC area with the robotic arm. The middle of the belt edge was also tucked to minimize the muscle contractions during stimulation. The strong muscle contractions could prevent participants from seeing the screen with stimuli and may also cause unpleasant sensations.</li>
	<li>When the reference tracker is placed on the participant&#39;s head, set the real-world landmarks (in this case, ears and the nasion) according to the previously found MRI landmarks using the pointer with a set of reference silver balls. Ensure that the Root Mean Square (RMS) Deviation value is not higher than 5 mm. If the value is higher, set the real-world landmarks again and recalculate the RMS Deviation value.</li>
	<li>Supplement these landmarks with a series of additional landmarks by the same pointer to define the participant&#39;s head surface. Add these points by creating continuous horizontal and vertical lines uniformly distributed along the head surface. A minimum of 300 additional surface landmarks are required. 
	NOTE: After the surface registration, the RMS Deviation value should be less than 2 mm to provide good registration quality. When adding additional points, ensure they are represented adequately on the head surface.</li>
	<li>After the registration ends, check that the software correctly registers the position of the pointer on the 3D model by placing it at the head surface (not inside the head or far from its surface).</li>
</ol>
5. Motor threshold definition
NOTE: Different montages can be chosen to attach the electrodes. For this experiment, the anode electrode was placed on the projection of the first dorsal interosseous (FDI) muscle of the right arm, which was chosen as the target to define the motor threshold. The cathode was placed on the projection of the distal extremity of the proximal phalanx of the index finger, while the ground electrode was placed on the bone of the right arm near the elbow.
<ol>
	<li>Scrub participants&#39; skin and remove remnants of the scrub with alcohol wipes.</li>
	<li>Take three clamp electrodes and insert them into the corresponding sockets of the amplifier (anode for the FDI muscle, cathode for the index finger bone, and the ground electrode for the area near the elbow).</li>
	<li>Stick three sticky electrodes to the participant&#39;s skin. While sticking the electrode to the FDI muscle, ask the participant to tense the FDI muscle by putting all the fingers together and stretching them, whereas to stick the electrode to the index finger bone, ask the participant to bend their finger.</li>
	<li>Attach clamp electrodes to sticky electrodes.</li>
	<li>Connect the amplifier to the charged battery.</li>
	<li>Ensure that the signal from the FDI muscle is not noisy. 
	NOTE: The signal is registered with the special software (Table of Materials). It is particularly necessary to ensure a good signal because, otherwise, the motor threshold will be either overstated or understated. The noise amplitude should not exceed 50 &#181;V peak-to-peak; otherwise, try some ways to make the participant&#39;s FDI muscle relaxed. If needed, place the participant&#39;s head on the pillow or ask the participant to strain his hand for a short time and then relax it.</li>
	<li>Set the stimulator intensity to 50% and then adjust it depending on the reaction to pulses, since the range of motor thresholds is considerable.</li>
	<li>Find the hand knob area in the precentral gyrus by orienting the coil according to the 3D individual head model. Ensure that the coil is placed tangentially to the head surface and oriented at 45&#176; with respect to the midline. While finding the motor hotspot, make several pulses in the hand knob area and record the points on the head surface where the amplitude of the motor evoked potentials is large.</li>
	<li>Repeat the pulses to the points with the highest motor response to check their stability. Increase or decrease the stimulation intensity to find the approximate intensity at which a stable motor response is found only in the potential hotspot.</li>
	<li>After choosing the hotspot, orient the coil in the chosen position and make 10 pulses with the intensity at which you choose the motor hotspot. Count the number of times when the amplitude of the motor evoked potential exceeds 50 &#181;V peak-to-peak. Adjust the stimulation intensity to a point where 5 out of 10 pulses of the motor evoked potential amplitude is equal to or higher than 50 &#181;V.</li>
</ol>
6. Preparation for experimental stimulation
<ol>
	<li>In order to start the experimental stimulation, switch the manual coil to the robotic arm coil and switch the cooling system to ensure the proper work of the robotic arm.</li>
	<li>To provide better access to the region of interest and to ensure that the coil does not prevent from seeing the screen, adjust the back of the armchair to make the reclining participant&#39;s position. Due to the shift of the participant&#39;s head, adjust the navigation system so that it can easily locate the reference tracker and all the required stimulation areas. If needed, the armchair can be lifted or put down to ensure the robotic arm can access the stimulation points.</li>
	<li>Before launching the experiment, check the robotic arm&#39;s positioning on the participant&#39;s head surface. Ensure the participant gradually gets accustomed to the stimulation frequency.</li>
	<li>Since the stimulation will be triggered in the experimental software, connect the stimulator and the trigger station with the parallel port.</li>
	<li>Activate the software of the station (Table of Materials) to synchronize the software with it and set the stimulation parameters. For the experiment itself, the number of pulses should be set to 20 for the 20 Hz stimulation, and the half-period should be set to 25 ms.</li>
	<li>During the training session, start with one pulse and then increase the number of pulses to 5, 10, 15, and finally to 20. After each pulse or train of pulses, ask the participant if the stimulation is comfortable. If the stimulation causes discomfort, stop the experiment and exclude the participant from the final sample. 
	NOTE: During the coil alignment, ensure the coil fits closely to the head surface but does not push it hard. If the coil pushes hard or does not remain stable on the head surface, the coil sensitivity settings can be adjusted.</li>
	<li>Adjust the screen position to make it fully visible for the participant in the reclining position. The mouse and the keyboard can be put on participants&#39; knees or on the pillow above. Ensure that the stimulation task is organized in randomized blocks with intervals between them when navigating the robotic arm to the required position on the head&#39;s surface. During the interval, the participant can have some rest.</li>
</ol>
7. Data analysis
<ol>
	<li>Choose the dependent variable (here, Likert-scale preference change) and independent variables for the analysis (here, choice (chosen/rejected), rating task (first/second), trial type (switch/no-switch/computer) and stimulation block (dmPFC/dlPFC/sham/vertex)).</li>
	<li>Choose the threshold value for statistical significance (here, p-value &#8804; .05).</li>
	<li>Test the normality of the responses distribution to choose parametric or non-parametric ANOVA statistical analysis.</li>
	<li>Conduct ANOVA to test the statistical significance of the preference change depending on the choice status, area of stimulation, target/control condition, presence of manipulation, and sense of agency (choice, rating task, trial type, stimulation factors).</li>
	<li>Conduct post-hoc pairwise comparisons to explore whether preference changes are significant within different stimulation blocks, trial types, and choices.</li>
	<li>Fit the linear mixed effects model and the ordinary least squares linear regression to test the significance of main effects (choice, rating task, trial type, and stimulation) and interaction effects.</li>
</ol>

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

According to the previous research, it was hypothesized that the inhibition of the left dlPFC or dmPFC activation should disrupt the process of preference change, demonstrating no choice-induced preference change due to the hard choice. Although actual results were inconsistent with the expected ones, several implications are important for future online rTMS research. The study builds upon and extends the findings of Izuma and colleagues10 and Colosio and colleagues13 by no...

<table><tbody><tr><td>Axilum Robotic TMS-Cobot&amp;nbsp;</td><td>Axilum Robotics, Schiltigheim, France</td><td>2/1/2002</td><td></td></tr><tr><td>BrainAmp ExG amplifier - bipolar amplifier</td><td>Brain Products, GmbH, Germany</td><td></td><td></td></tr><tr><td>BrainVision Recorder 1.21.0004</td><td>Brain Products, GmbH, Germany</td><td></td><td></td></tr><tr><td>Chair with neckrest</td><td>MagVenture, Farum, Denmark</td><td>9016B0081</td><td></td></tr><tr><td>Electrode wires for surface EMG</td><td>EBNeuro, Italy</td><td>6515</td><td></td></tr><tr><td>Localite TMS Navigator - MR-based software, import data for&lt;br/&gt; morphological MRI (DICOM, NifTi)</td><td>Localite, GmbH, Germany</td><td>10226</td><td></td></tr><tr><td>Localite TMS Navigator - Navigation patform, Premium edition</td><td>Localite, GmbH, Germany</td><td>21223</td><td></td></tr><tr><td></td><td></td><td></td><td></td></tr><tr><td>MagVenture 24.8 coil tracker,&lt;br/&gt; Geom 1</td><td>Localite, GmbH, Germany</td><td>5221</td><td></td></tr><tr><td>MagPro X100 MagOption - transcranial magnetic stimulator</td><td>MagVenture, Farum, Denmark</td><td>9016E0731</td><td></td></tr><tr><td>Nuprep Skin Prep Gel</td><td>Weaver and Company, USA</td><td></td><td></td></tr><tr><td>Plastic non traumatic button</td><td>E.M.S., Bologna, Italy</td><td>FIA-PG905/99</td><td></td></tr><tr><td>Rubber belt &amp;ndash; 75 cm</td><td>E.M.S., Bologna, Italy</td><td>FIA-ER-PG905/8</td><td></td></tr><tr><td>8-shaped coil MC-B65-HO-2</td><td>MagVenture, Farum, Denmark</td><td>9016E0462</td><td></td></tr><tr><td>Sticky tape</td><td></td><td></td><td></td></tr><tr><td>Surface Electrodes for EEG/EMG</td><td>EBNeuro, Italy</td><td>6515</td><td></td></tr><tr><td>Trigger Station TS832U</td><td>BrainTrends ltd, Rome, Italy</td><td></td><td></td></tr></tbody></table>

online repetitive transcranial magnetic stimulation of dorsomedial and dorsolateral prefrontal cortex in cognition decision making, and cognitive dissonance

Online Repetitive Transcranial Magnetic Stimulation of Dorsomedial and Dorsolateral Prefrontal Cortex in Cognition Decision Making, and Cognitive Dissonance

Transcranial magnetic stimulation (TMS) is a powerful method for revealing causal links between specific brain regions and cognitive functions. While offline TMS has traditionally dominated cognitive neuroscience research, online repetitive TMS (rTMS) presents undoubted advantages, enabling stimulation concurrent with task performance. Leveraging advancements in this stimulation method, the study introduces a novel online rTMS protocol utilizing neuronavigation and robotic systems to precisely target dorsolateral and dorsomedial prefrontal cortices during an experimental procedure. Moreover, the utility of online rTMS in investigating the neural mechanisms underlying cognitive dissonance and neurochronometry of the choice-induced preference change was explored. For that purpose, a protocol for the high-frequency online rTMS was applied during the procedure with a within-subject blocked design and two control conditions. The study leads to principal conclusions for future TMS research, such as the importance of a proper set of time, location, and parameters of the stimulation, electric field modulation, and appropriate control conditions.

46 participants were recruited and prepared for the stimulation, but 10 participants had to be excluded from the analysis (8 females and 2 males). Seven participants felt discomfort during the stimulation of the dlPFC and dmPFC because of the strong muscle contractions, 2 participants noticed the manipulation in switch trials during the second rating task, and the data for 1 participant were not recorded due to a technical error. A final sample for the rTMS study consisted of 36 participants (19 males; aged between 18 an...

This protocol presents a more precise and effective method of repetitive transcranial magnetic stimulation of the dorsolateral and dorsomedial prefrontal cortices during an experimental task using neuronavigation and robotic systems. Based on the results, crucial implications are suggested for future online stimulation research.

Transcranial magnetic stimulation (TMS) is a powerful method for revealing causal links between specific brain regions and cognitive functions. While ...

The overall goal of this procedure is to introduce a precise and effective method of repetitive transcranial magnetic stimulation using the neuron navigation system and the TMS robot to target the dorsolateral and dorsomedial prefrontal cortices during an experimental task. The main advantage of this protocol is the maximization of the RTMS effect as a result of more precise stimulation at a particular period of time during the experimental procedure, controlling its beginning and ending, relying on the stimulus onset and offset. This method can help to stimulate brain areas reducing the experimental assistance and influence on a participant's performance during an experimental task.The protocol can be applied to different brain areas and experimental tasks. The MRI-assisted navigation system provides an accurate simulation of the target brain area and allows the TMS robot to adjust the position of its robotic arm according to the micro movements of the participants'head during the experiment. The further described protocol of the RTMS for inhibiting the DLPC and DMPC activation must be applied with the service of the MRI scan brain navigated system, magnetic stimulator, and robotic arm.The MRI system navigation system provides an accurate stimulation of the target brain area, allowing the robotic arm to adjust its position according to the micro movements of the participant's head during the experiment. For this purpose, neuroanatomical MRI must be provided for all subjects of the study. The navigation system requires a specific set of equipment, such as the calibration plate for tracking a coil, the reference tracker for the participant's head localization, the pointer for setting a group of reference landmarks, and the infrared camera for tracking objects in space.Coil calibration is provided by using the calibration plate, whereas the robotic arm does not need any additional equipment to be calibrated. All of them have silver reference balls, allowing the camera to recognize the objects in space. Align the calibration plate with the coil.Set the scale on both the calibration plate and coil and calibrate using the software. Calibrate the robotic arm force sensor using the software. Press the robotic arm surface with different force levels in order to prevent hard pressure on the participant's head, but ensure a snug fit to the head during stimulation.A major part of the navigation system preparation is to prepare individual MRI scans for the patient's registration procedure. It can be done even before a participant comes. The main goal lies in matching the individual brain coordinates and the coordinates in universal coordinate systems, such as MNI and Talairach.Make a 3D model of the participant's head according to the software of the TMS system you use and then do the Talairach definition procedure. Set three benchmarks, namely the anterior commissure posterior commissure, and falx cerebri. And then adjust the Talairach space grid to the size of the 3D model of the head.Set the targets of the feature stimulation and the required rotation angle according to the predefined MNI coordinates of your study. Calculate entries for the targets as the correspondent locations on the surface of the participant's head to position the robotic arm during the stimulation. We put entries for the vertex control point manually as the midpoint on the head surface.However, you can also insert the standard coordinates from reliable studies as the target points and calculate entries. Set MRI landmarks on the 3D model of your participant's head for more accurate tracking of the participant's head location. For our study, we use landmarks on the left and right ears and the nasion, but you can use any other landmarks for your convenience.The patient registration procedure is done when the participant arrives. Provide the consent forms regarding information about the experiment and ear blocks for protecting the participant's hearing. Place the reference tracker on the participant's head.The reference tracker has to be attached to the participant's head at the point where the robotic arm will not occasionally touch the tracker during the stimulation. The tracker has three silver reflective reference balls, which are identified by the navigation system to localize the coordinates of the participant's head during the procedure and the experiment. Conventionally, the tracker is placed on the forehead area.However, since we wanted to be sure that the entry targets of the DLPC and DMPC are available for the navigation system and can be reached by the robotic arm, we place the tracker between the forehead and the right ear. You can place it near the left ear as well, depending on the leading reference plate of the robotic arm. Fix the reference tracker on the participant's head by the elastic belt tightly enough, but quite comfortable for the participant.The belt fixation is flexible depending on the participant's head size. We moved the belt down to the forehead area, bent it down, and fixed it to provide better access to the DMPC area by the robotic arm. We also tucked the middle of the belt edge to minimize the muscle contractions during stimulation.The strong muscle contractions could prevent participants from seeing the screen with stimuli and might also cause unpleasant sensations. When the reference tracker is placed on the participant's head, set the real-world landmarks, ears, and the nasion in our case, according to the previously found MRI landmarks by using the pointer with a set of reference silver balls. The root mean square deviation value should not be higher than five millimeters.If the value's higher, set the real-world landmarks again and recalculate the root mean square deviation value. Supplement these landmarks with a series of additional landmarks by the same pointer to define the participant's head surface. These points are added by creating continuous, horizontal and vertical lines uniformly distributed along the head surface.A minimum of 300 additional surface landmarks are required. After the surface registration, the root mean square deviation value should be less than two millimeters to provide a good registration quality. While putting additional points, you should ensure that points are represented adequately on the head surface.After the registration ends, check that the software correctly registers the position of the pointer on the 3D model by placing it at the head surface. You can choose different montages to attach the electrodes. We put the anode electrode on the projection of the first dorsal interosseus muscle of the right arm, which was chosen as the target to define the motor threshold.The cathode was placed on the projection of the distal extremity of the proximal phalanx of the index finger, while the ground electrode was placed on the bone of the right arm near the elbow. Scrub participant's skin and remove remnants of the scrub with alcohol wipes. Take three clamp electrodes and insert them into the correspondent sockets of the amplifier.Anode for the FDI muscle, cathode for the index finger bone, and the ground electrodes for the area near the elbow. Connect the amplifier to the charged battery. Stick three sticky electrodes to the participant's skin.While sticking the electrode to the FDI muscle, ask the participant to test the FDI muscle by putting all the fingers together and stretching them. Whereas to stick the electrode to the index finger bone, ask the participant to bend their finger. Attach clamp electrodes to sticky electrodes.Ensure that the signal from the FDI muscle is not noisy. The signal is registered with a special software. We use the BrainVision Recorder.It's particularly necessary to ensure a good signal because otherwise, the motor threshold will be either overstated or understated. The noise amplitude should not exceed 50 microvolts peak-to-peak, otherwise, try some ways to make the participant's FDI muscle relaxed. You can place the participant's head on the pillow or ask the participant to strain his hand for a short time and then relax it.Set the stimulator intensity to 50%and then adjusted depending on the reaction to pulses. Since the range of motor threshold is considerable, find the hand knob bearing at the precentral gyrus by orienting the goal according to the 3D individual head model. The goal should be put tangential to the head surface and oriented at 45 degrees with respect to the midline.While finding the motor hotspot, make several pulses in the hand knob area and record the points on the head surface where the amplitude of the motor evoked potentials was large. Repeat the pulses to the points with the highest motor response to check their stability. You should increase or decrease the stimulation intensity to find the approximate density at which you can find the stable motor response only in the potential hotspot.After choosing the hotspot, orient the goal in the chosen position and make 10 pulses with the intensity at which you choose the motor hotspot. You should count the number of times when the amplitude of the motor evoked potential exceeds 50 microvolts peak-to-peak. You should again adjust the stimulation intensity in order to find the one at which you can find that four out of 10 passes.The motor evoked potential amplitude is equal to or higher than 50 microvolts. In order to start the experimental stimulation, switch the manual coil to the robotic arm coil and switch the cooling system to ensure the proper work of the robotic arm to provide better access to your region of interest, and to ensure that the coil does not prevent from seeing the screen. Adjust the back of the arm chair to make the reclining participant's position.Due to the shift of the participant's head, you should adjust the location system, so that it can easily locate the reference tracker and all the required stimulation areas. If needed, the arm chair can be lifted or put down to ensure the robotic arm can access the stimulation points. Before launching the experiment, check the good position of the robotic arm on the participant's head surface, besides, the participants should gradually get accustomed to the stimulation frequency.Since the stimulation will be triggered in the experimental software, connect the stimulator in the trigger station with the parallel port. Activate the trigger station software to synchronize the software with the trigger station and set the stimulation parameters. For the experiment itself, the number of pauses should be set to 20 for the 20 hertz stimulation, and the half period should be set to 25 milliseconds.During the training session, start with one pulse and then increase the number of pulses to 5, 10, 15, and finally to 20. After each pulse or cranial passes, ask the participant whether the stimulation is comfortable. If the stimulation causes discomfort, stop the experiment and exclude the participant from the final sample.During the coil alignment, you should ensure that the coil fits closely to the head surface, but does not push it hard. If the coil pushes hard or does not remain stable on the head surface, the coil sensitivity settings can be adjusted. Adjust the screen position to make it fully visible for the participant in the reclining position.The mouse and the keyboard can be put on participant's knees or the pillow above. The stimulation task is organized in randomized blocks with the intervals between them when you should navigate the robotic arm to the required position on the head surface. During the interval, the participant can have some rest.The main question of interest for the analysis was whether people changed their preferences for images, rating them for the second time compared to the first rating task differently for stimuli they chose or rejected between these two ratings. Namely, we were interested in whether the preference score and the second rating task increased or decreased compared to the first rating task, and most importantly, whether this positive or negative change is consistent with the choice made for different stimulation blocks, DLPC, DMPC, and two control blocks, vertex and sham. We can see that the difference in preference change is consistent with the choice.Participants diminish their preferences more largely for rejected than chosen images. The difference in preference change is significant for DLPC, vertex, and sham stimulation blocks, which means that we could reproduce the behavioral effect in control conditions. However, as opposed to what we expected, the downregulation of DLPC did not affect the preference change process.While according to the results, DMPC was suppressed, which lead to no consistent preference change for chosen versus rejected stimuli. Based on our results, several implications are crucial for future online rTMS research. Controlling for the place of the stimulation is very important.Unlike in modern online experiments, when we can observe TMS effects using TMS, in cognitive experiments, such an observation is not available. One way to overcome this complication would be to refer to the place of the stimulation in the FMRI results. However, such interpretation often suffers from the reserved inference problem, or namely, the lack of sufficient selectivity of the area in question.A special attention must be paid to the TMS intensity. Finding stimulation intensity by measuring MEP does not fully account for the distribution and intensity of the electric field induced in each trial. Recently, researchers have suggested modeling the electric field in TMS studies, which is a more accurate way to determine the stimulation intensity.To target the neural substrate of cognitive functions, it is more beneficial to apply TMS and EEG, or TMS and FMRI concurrently, or before and after the TMS procedure if the neural response and interest cannot be directly measured, such as dorsomedial and dorsolateral prefrontal cortices activity. We conclude that this improvements to the protocol can make it applicable to other cognitive studies that presume the involvement and causal role of the DLPC and DMPC in cognitive processes of interest.

online-repetitive-transcranial-magnetic-stimulation-dorsomedial

Research

JoVE Journal

Neuroscience

Source: Lioumis, P. et al. Combined Transcranial Magnetic Stimulation and Electroencephalography of the Dorsolateral Prefrontal Cortex. J. Vis. Exp. (2018)This video demonstrates a protocol for combining transcranial magnetic stimulation and electroencephalography to assess cortical excitability and the balance between excitation and inhibition in the dorsolateral prefrontal cortex.

Combined Transcranial Magnetic Stimulation and Electroencephalography of the Dorsolateral Prefrontal Cortex

Source: Dunlop, K., et al. MRI-guided dmPFC-rTMS as a Treatment for Treatment-resistant Major Depressive Disorder. J. Vis. Exp. (2015)This video demonstrates the procedure for MRI-guided repetitive transcranial magnetic stimulation (rTMS) targeting the dorsomedial prefrontal cortex (dmPFC) to treat depression.

MRI-Guided Repetitive Transcranial Magnetic Stimulation to the Dorsomedial Prefrontal Cortex

Transcranial direct current stimulation (tDCS) over the cerebellum exerts a remote effect on the prefrontal cortex, which can modulate cognition and performance. This was demonstrated using two information-processing tasks of varying complexity, whereby only cathodal tDCS improved performance when the task was difficult, but not easy.

Modulating Cognition Using Transcranial Direct Current Stimulation of the Cerebellum

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.

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

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.

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

The protocol presented here is for TMS-EEG studies utilizing intracortical excitability test-retest design paradigms. The intent of the protocol is to produce reliable and reproducible cortical excitability measures for assessing neurophysiological functioning related to therapeutic interventions in the treatment of neuropsychiatric diseases such as major depression.

Threats reliably evoke shifts in high-level ideological investment, but little work to date has explored the neural mechanisms underlying these dynamics. This paper describes how continuous theta burst transcranial magnetic stimulation may be employed to test the contribution of the posterior medial frontal cortex (and/or other regions) to threat-related ideological shifts.

Continuous Theta Burst Stimulation of the Posterior Medial Frontal Cortex to Experimentally Reduce Ideological Threat Responses

We present a protocol and a feasibility study for applying transcranial direct current stimulation (tDCS) and neuroimaging assessment in online gamers.

Transcranial Direct Current Stimulation for Online Gamers

Transcranial Magnetic Stimulation (TMS) and low-frequency TMS (lfTMS) have been demonstrated to be major contributors to brain literature. Here we highlight the methods for investigating the cortical correlates of self-deception using TMS.

Employing Transcranial Magnetic Stimulation in a Resource Limited Environment to Establish Brain-Behavior Relationships

This study proposed an experimental paradigm that applies High-Definition Transcranial Direct Current Stimulation (HD-tDCS) to improve human metacognition in human-AI delegation tasks. The results demonstrated the effectiveness of HD-tDCS in enhancing metacognitive sensitivity.

High-definition Transcranial Direct Current Stimulation over Right Dorsolateral Prefrontal Cortex to Enhance Metacognitive Sensitivity

This article presents a clinical protocol for repetitive transcranial magnetic stimulation (rTMS) with individualized symptom provocation in obsessive-compulsive disorder (OCD), following parameters from protocols cleared by the FDA.

Protocol for Repetitive Transcranial Magnetic Stimulation with Symptom Provocation to Treat Obsessive-compulsive Disorder

Learn precise rTMS targeting of dorsolateral and dorsomedial prefrontal cortex using neuronavigation and robotic systems during cognitive tasks. This method enhances stimulation accuracy for cognitive neuroscience research.

Online Repetitive Transcranial Magnetic Stimulation of Dorsomedial and Dorsolateral Prefrontal Cortex in Cognition Decision Making, and Cognitive Dissonance (Video) | JoVE Journal

Online Repetitive Transcranial Magnetic Stimulation of Dorsomedial and Dorsolateral Prefrontal Cortex in Cognition Decision Making, and Cognitive Dissonance

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