This work was supported by NIH grant P20 GM109098, NSF and WVU ADVANCE Sponsorship Program (VG), and WVU departmental start-up funds.

All participants involved in experimentation undergo informed consent procedures approved by the West Virginia University Institutional Review Board (IRB).
1. Overall System Characteristics, Design, and General Experimental Task
Note: The complete setup is comprised of the following major components: EMG equipment and associated digital acquisition (DAQ) equipment; a motion capture system (this protocol incorporates an active LED system); a TMS unit with a figure-of-eight coil and stereotaxic localization equipment; a VR headset and associated computer and software; and a custom synchronization circuit. Figure 1 schematically outlines the connectivity between the protocol components.
<ol>
	<li>Connection of System Components
	<ol>
		<li>Connect EMG pre-amplifier to main amplifier.</li>
		<li>Connect output of EMG amplifier to DAQ recording equipment input block using BNC or similar connections.</li>
		<li>Connect DAQ recording equipment to dedicated computer that will execute a data acquisition script (supplementary file).</li>
		<li>Connect VR control computer parallel output to custom circuit unit (see next section for details).</li>
		<li>Connect synchronization and motion capture triggering outputs from custom circuit to DAQ recording block alongside EMG signal connections.</li>
		<li>Split motion capture trigger and connect it to the &#8220;Analog Input Start&#8221; port on the EMG DAQ equipment as well as the trigger connection on the computer that controls motion capture equipment. 
		Note: The temporal difference between the beginnings of the respective data acquisition streams for the described equipment (motion capture and EMG) can range from 160-190 msec. This temporal difference motivated the design of the synchronization circuit described in this protocol and is likely caused by the software and hardware differences between these two systems.</li>
		<li>Connect TMS trigger port on custom circuit unit to BNC input trigger on the TMS control unit.</li>
		<li>Establish network connectivity between the VR and motion capture computers using vendor-provided software and physical network connections.</li>
		<li>Connect VR headset to VR computer and ensure operability with any scripts/programs that display virtual environments to participants.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/52906/52906fig1.jpg" /> 
Figure 1: Connectivity of entire setup. This layout describes the general connectivity between the elements of our system. The synchronization circuit is described elsewhere in the text in more detail. The blue trace corresponds to the signal that starts both motion capture and EMG data streams. This event is the source of the temporal delay of up to 190 msec using the equipment described in this protocol. The red trace corresponds to the VR-initiated synchronization event that is concomitantly recorded by the motion capture and EMG systems and subsequently used for temporal alignment of the respective data streams. <a href="https://www.jove.com/files/ftp_upload/52906/52906fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
2. General Details of System Integration and Synchronization
Note: Synchronization of the separate data acquisition systems in this protocol (motion capture and EMG) is accomplished through the use of an event signal that is common to all recording streams. Using a common event, all of the signals can be temporally realigned after data collection to minimize real-time recording discrepancies (upwards of 190 msec using the equipment in this protocol). In this protocol, the common signal originates from the VR system as a parallel port signal. The common signal is routed to a circuit that permits synchronization of the separate data streams through direct recording with EMG signals and by simultaneously turning off a motion capture LED. The circuit is constructed using basic tools and techniques for building electronic components, similar to circuits described elsewhere9.
<ol>
	<li>Design, Layout, and Construction of Synchronization Circuit
	<ol>
		<li>Identify any analog TTL-based triggering mechanisms on equipment control units (e.g. TMS, motion capture) and become familiar with triggering requirements such as TTL pulse direction (positive/negative) and amplitude. Analog triggering mechanisms often possess common &#8220;BNC&#8221; coaxial connectors that make connecting components simple.</li>
		<li>Add an additional LED to the motion capture system to be used for signal synchronization; route the LED&#8217;s wires through the synchronization circuit (Figure 3).</li>
		<li>Determine the electrical component parameters (i.e. resistance, capacitance) needed to turn off the synchronizing LED for a specific amount of time. Find the amount of time that the circuit&#8217;s syncing LED is turned off by the equation: t = 1.1*R1*C1. This time is suggested to be less than the average duration of an experimental movement. For example, the currently described experiment required a resistor and capacitor rated at approximately one megaohm and one microfarad, respectively.</li>
		<li>Use a soldering iron to adhere electrical components to a printed &#8220;protoyping&#8221; or &#8220;project&#8221; circuit board following the schematic shown in Figure 3. Enclose this circuit in a commonly available plastic &#8220;project&#8221; box; it will likely be necessary to drill holes in this box for the BNC connectors. The circuit can readily be powered by 5 V USB power from a desktop computer; it will be necessary to deconstruct a USB cable to isolate the power and ground wires. Bypass capacitors may also be needed to regulate the power to the 555 chip (not shown in Figure 3).</li>
		<li>Inspect the circuit board for any unintended solder bridges between electrical components. If found, remove solder with a suction tool or heat the solder and mechanically remove the bridging connection.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 2" src="/files/ftp_upload/52906/52906fig2.jpg" /> 
Figure 2: Trial flowchart. This flowchart outlines the stimulus and signal events that occur during a typical experimental trial that includes TMS stimulation. Parallel port codes that occur throughout a trial are shown in the DB25 schematic symbols (light blue).
<ol start="2">
	<li>Synchronization Details
	<ol>
		<li>Using a flowchart similar to Figure 2, determine when individual pieces of equipment should be triggered during the course of an experimental movement. For example, some equipment may be individually triggered, while others may be simultaneously triggered.</li>
		<li>At time points that require triggering or signaling (e.g. blue parallel port symbols in Figure 2), determine which parallel ports signal lines to use and incorporate them into the VR system. This is accomplished by sending numerical values to the parallel port at the specified times during movements, each line representing a binary digit. For more details about parallel port based signaling, please refer to the Discussion.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 3" src="/files/ftp_upload/52906/52906fig3.jpg" /> 
Figure 3: Synchronization Circuit. This schematic displays the layout of our custom synchronization circuit. The default output of the NAND gate is a high voltage state; this voltage output is sent to the gate of a transistor through which the sync LED&#8217;s circuit is routed. This default state renders the circuit closed, which maintains the LED in a lighted state. Upon receiving a sync trigger parallel port signal (red trace in inset), an internal state of the 555 device is flipped rendering the output into a high state, shutting off the LED (blue trace). When this occurs, the voltage on C1 (green trace) builds up to a voltage that resets the internal state of the 555, reactivating the LED. The parallel port sync trigger signal is also directly routed to a BNC connector that is connected to the TMS input trigger port. Note: The direction of this trigger signal may have to be reversed (from positive- to negative-going or vice-versa) depending on an investigator&#8217;s specific equipment requirements. The addition of an &#8220;inverter&#8221; chip on this trigger output would easily accomplish this task. <a href="https://www.jove.com/files/ftp_upload/52906/52906fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
3. Experimental Procedures
<ol>
	<li>Safety Procedures and Informed Consent
	<ol>
		<li>Ensure that all experimental procedures are approved by an Institutional Review Board (IRB). Explain all procedures to participants and acquire informed consent with IRB approved documentation.</li>
		<li>After acquiring informed consent, conduct a basic TMS safety screening with participants to ensure they do not have tinnitus, a family history of epilepsy or seizures, or other conditions with elevated risks of seizure.</li>
		<li>During TMS stimulation, strictly require the use of protective earplugs to prevent hearing damage.</li>
	</ol>
	</li>
	<li>Electromyography Collection
	<ol>
		<li>Depending on the scientific goals of a reader&#8217;s study, determine from which arm muscles to record EMG signals. For the study described in this protocol,&#160; torques generated at the shoulder and elbow during movement were investigated. Thus, EMG signals recorded were from the major superficial muscles that act on these two joints, such as the deltoid, pectoralis, biceps, triceps, and brachioradialis.</li>
		<li>Make all necessary electrical connections between various EMG equipment including amplifiers, preamplifiers, sensor wires, and sensor pads according to the manufacturer&#8217;s specifications by connecting matching connectors.</li>
		<li>Prepare each electrode site by lightly cleaning it with an alcohol swab, removing any excessive hair with a razor, and by applying a mild abrasive gel. Proper site preparation will ensure consistent and low electrode-to-skin impedance values (&#60;10 kOhms) and high signal-to-noise ratio of recorded EMG signals.</li>
		<li>Have subjects perform isometric contractions designed to isolate individual muscles of interest based upon accepted anatomical and biomechanical descriptions10. For example, to isolate the biceps, ask the participant to resist an imposed extension of the elbow.</li>
		<li>After having subjects perform muscle-isolating contractions, affix differential bipolar EMG electrodes over the thickest, central portion, or &#8220;belly&#8221;, of each muscle at accepted locations11. This ensures coverage of a maximal number of muscle fibers and minimizes &#8220;crosstalk&#8221; between neighboring muscles. Be sure to align the bipolar electrodes&#8217; longest axes along the muscles, parallel to the fibers.</li>
		<li>Affix the EMG ground electrode according to equipment specifications (e.g. the skin over the C7 vertebra).</li>
		<li>Record amplified EMG signals through DAQ equipment controlled by a custom computer script. The script used in the current protocol is attached as a supplementary file.</li>
		<li>Adjust gains applied to recorded signals to desired level by moving dials on the EMG preamplifier. Avoid gain values that cause recorded signals to exceed the input range of the recording equipment (typically 5V). Common EMG gain values are between 1,000-4,000.</li>
		<li>Perform similar isometric contractions to those performed in step 3.2.4 and visually inspect EMG signals to ensure that they are of high quality (i.e. high signal-to-noise ratio). Reposition electrodes and change the signal gain if necessary.</li>
	</ol>
	</li>
	<li>Motion Capture System Preparation
	<ol>
		<li>Calibrate motion tracking cameras using vendor-supplied instructions and equipment according to manufacturer&#8217;s instructions.</li>
		<li>Using tape and other wrapping materials, attach active LED sensors to bony landmarks near the joints of the arm and other anatomical points of interest used in the construction of biomechanical models: the distal phalanx of the index finger, radial and ulnar styloid processes at the wrist, olecranon process at the elbow, coracoid and acromion processes of the shoulder, sternoclavicular notch, xiphoid process, and spinous process of C7. Attach another LED to the VR headset to set the view point in the virtual environment.</li>
		<li>Connect each LED to a wiring harness that is attached to the wireless driver unit. Turn on driver unit and ensure proper illumination of all LEDs.</li>
		<li>Position the synchronization LED in a convenient location away from the subject, but within clear view of the cameras.</li>
	</ol>
	</li>
	<li>Transcranial Magnetic Stimulation Stereotaxic Localization
	<ol>
		<li>Calibrate hardware and software designed for TMS registration12, to allow for accurate coil placement. This generally involves co-registering TMS coils with anatomical landmarks such as the nasion, preauricular points, and nose tip. Stereotaxic registration between a participant and the stimulation coil is integral to consistent stimulation localization.</li>
	</ol>
	</li>
	<li>MEP Hot-spot Localization and MEP Threshold Pprocedures
	<ol>
		<li>Perform so-called &#8220;hot-spot&#8221; techniques to locate TMS-sensitive regions of cortex that produce the greatest amplitude MEPs with the lowest threshold upon stimulation8,13,14. Transcranial magnetic stimulation for studying motor systems typically involves stimulating a cortical area that controls movement in a specific body part (e.g. the arm and hand)15.</li>
		<li>Record the location of any ideal stimulation sites on the participants scalp with the calibrated stereotaxic registration equipment and associated software. After each location is recorded with the software, ensure its accuracy by relocating the spot and stimulating again, looking for similar MEP responses.</li>
	</ol>
	</li>
	<li>Behavioral Task in Virtual Reality
	<ol>
		<li>Design the parameters of the behavioral task (e.g. reaching movements) to be used in the experiment. In the current study, the task is to reach to virtual targets placed sequentially in different spatial locations. The size of the targets defines the accuracy with which the participants move. Design the movements such that varying directions and magnitudes of joint torques are evoked as participants reach for targets.</li>
		<li>Setup the VR environment that guides subjects through the behavioral task using commercial VR software that is compatible with the headset and motion tracking system according to the manufacturer&#8217;s protocol. Become familiar with the software package&#8217;s required computational resources and programming language requirements. Common VR software packages have the ability to be programmed with languages including Python, C++, C#, and others. Additionally, program analog outputs through the parallel port for synchronization and marking of specific events of interest (Figure 2). In the current experiment, the VR software outputs events at the start of each repetition of the task and at times of desired TMS stimulation.</li>
		<li>Connect the VR output to the synchronization circuit (Figure 3) and/or the other equipment to be synchronized using cables with matching connectors.</li>
		<li>Instruct subjects to perform the VR behavioral task. In the current study, the VR environment was presented using a head-mounted display in which participants viewed arrays of spherical targets. Using the VR software, program specific movement sequences by altering the appearance of targets (color, location, etc.) and familiarize participants with these actions. Additionally inform participants of any other desired movement constraints. For example, participants in the current study were asked to keep all arm segments within a vertical plane of movement while reaching for targets.</li>
		<li>Once participants are accustomed to the experimental movements, record EMG and motion capture data, and synchronizing signals using custom scripts or vendor-supplied software packages. Adjust the sampling rate of each data acquisition system to desired values; additionally become familiar with and adjust any manufacturer-specific parameters such as motion-tracking LED intensity.</li>
	</ol>
	</li>
</ol>

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L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Learning+a+visuomotor+rotation:+simultaneous+visual+and+proprioceptive+information+is+crucial+for+visuomotor+remapping.">Learning a visuomotor rotation: simultaneous visual and proprioceptive information is crucial for visuomotor remapping.</a> Exp. Brain Res. 203 (1), 75-87 (2010).</li><li>Sarlegna, F. R., Sainburg, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+roles+of+vision+and+proprioception+in+the+planning+of+reaching+movements.">The roles of vision and proprioception in the planning of reaching movements.</a> Adv. Exp. Med. Biol. 629, 317-335 (2009).</li><li>Lillicrap, T. 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The authors have no conflicts of interest to declare.

The objective of this article is to describe a method for incorporating VR into the study of human motion and a method for synchronizing various data streams. Virtual Reality will expand the capabilities of researchers that attempt to recreate real-world movement scenarios in a laboratory setting. Combining VR with other neuromuscular recording and stimulus methodologies forms a powerful suite of tools for comprehensively studying human motor control mechanisms. The resulting multidimensional datasets obtained during met...

Virtual reality (VR) is rapidly becoming an accessible research tool for use in a number of fields, including the study of human motion. The study of upper limb movement is especially benefited by incorporating VR. Virtual reality permits the rapid customization of experimental parameters designed to investigate specific kinematic and dynamic features of arm movement control. These parameters can be individually adjusted for each subject. For example, the locations of virtual targets can be scaled to ensure identical initial arm posture across subjects. Virtual reality also allows the manipulation of visual feedback during experiments, which is an invaluable tool in visuomotor research1&#8211;5.
The use of realistic VR environments with other biomechanical tools will also permit naturalistic movement scenarios in which to test movement patterns. This arrangement is becoming increasingly valuable to the study and practice of rehabilitation after disease and injury6,7. Mimicking naturalistic movements and environments (e.g. performing movements in a virtual kitchen) in a clinical setting will enable rehabilitation specialists to more precisely describe an individual&#8217;s impairments in a real-world context. Highly individualized impairment descriptions will allow for more focused treatment strategies, potentially increasing the efficacy and reducing the duration of rehabilitation.
Combining VR with other tools such as transcranial magnetic stimulation (TMS), surface electromyography (EMG), and full body motion capture, creates an extremely powerful and flexible platform for studying the neuromuscular control of movement in humans. Transcranial magnetic stimulation is a powerful non-invasive method of measuring the excitability and functional integrity of descending motor pathways (e.g. corticospinal tract) through EMG responses such as motor evoked potentials (MEPs)8. Modern three-dimensional motion capture systems also enable researchers to study neuromuscular activity together with resulting movement kinematics and dynamics. This permits the creation of extremely detailed models of the musculoskeletal system as well as the testing of hypotheses regarding the structure and function of neural controllers. These studies will expand our scientific knowledge of the human sensorimotor system and lead to improvements in treatment of musculoskeletal and neurological disorders.
However, one major problem with multifunctional systems is the synchronization of separately recorded data streams (e.g. motion capture, EMG, etc.). The goal of this protocol is to describe a generalizable arrangement of common commercially available systems to simultaneously record biomechanical and physiological measurements during movement. Other investigators using equipment from different manufacturers may have to alter elements of this protocol to fit their specific needs. However, general principles from this protocol should still be applicable.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Transcranial magnetic stimulator</td>
			<td>Magstim</td>
			<td>N/A</td>
			<td>TMS stimulator and coils</td>
		</tr>
		<tr>
			<td>Impulse X2</td>
			<td>PhaseSpace</td>
			<td>N/A</td>
			<td>Motion capture system</td>
		</tr>
		<tr>
			<td>MA300 Advanced Multi-Channel EMG System</td>
			<td>Motion Lab Systems</td>
			<td>MA300-28</td>
			<td>EMG pre-amplifier and amplifier</td>
		</tr>
		<tr>
			<td>Norotrode EMG electrodes</td>
			<td>Myotronics</td>
			<td>N/A</td>
			<td>EMG electrodes</td>
		</tr>
		<tr>
			<td>BNC-2111 Single-Ended, Shielded BNC Connector Block</td>
			<td>National Instruments</td>
			<td>779347-01</td>
			<td>BNC Connector Block</td>
		</tr>
		<tr>
			<td>NI PXI-1033 
			5-Slot PXI Chassis with Integrated MXI-Express Controller</td>
			<td>National Instruments</td>
			<td>779757-01</td>
			<td>DAQ chassis</td>
		</tr>
		<tr>
			<td>NI PXI-6254 
			16-Bit, 1 MS/s (Multichannel), 1.25 MS/s (1-Channel), 32 Analog Inputs</td>
			<td>National Instruments</td>
			<td>779118-01</td>
			<td>DAQ card</td>
		</tr>
		<tr>
			<td>SHC68-68-EPM Cable (2m)</td>
			<td>National Instruments</td>
			<td>192061-02</td>
			<td>Shielded cable</td>
		</tr>
		<tr>
			<td>DK1 or DK2</td>
			<td>Oculus VR</td>
			<td>N/A</td>
			<td>Ocuclus Rift headset</td>
		</tr>
		<tr>
			<td>Vizard 5 Lite</td>
			<td>WorldViz</td>
			<td>N/A</td>
			<td>Virtual reality software</td>
		</tr>
		<tr>
			<td>C1 and C2 capacitors</td>
			<td>varied</td>
			<td>N/A</td>
			<td>Adjust values to suit</td>
		</tr>
		<tr>
			<td>R1 and R2 resistors</td>
			<td>varied</td>
			<td>N/A</td>
			<td>Adjust values to suit</td>
		</tr>
		<tr>
			<td>CD4011 NAND gate</td>
			<td>varied</td>
			<td>N/A</td>
			<td>NAND gate</td>
		</tr>
		<tr>
			<td>2N2222 transistor</td>
			<td>varied</td>
			<td>N/A</td>
			<td>Transistor</td>
		</tr>
		<tr>
			<td>NE555 timer circuit</td>
			<td>varied</td>
			<td>N/A</td>
			<td>Timer circuit</td>
		</tr>
		<tr>
			<td>DB25 and USB connectors</td>
			<td>varied</td>
			<td>N/A</td>
			<td>parallel and USB connectors</td>
		</tr>
	</tbody>
</table>

multifunctional setup for studying human motor control using transcranial magnetic stimulation, electromyography, motion capture, and virtual reality

The study of neuromuscular control of movement in humans is accomplished with numerous technologies. Non-invasive methods for investigating neuromuscular function include transcranial magnetic stimulation, electromyography, and three-dimensional motion capture. The advent of readily available and cost-effective virtual reality solutions has expanded the capabilities of researchers in recreating &#8220;real-world&#8221; environments and movements in a laboratory setting. Naturalistic movement analysis will not only garner a greater understanding of motor control in healthy individuals, but also permit the design of experiments and rehabilitation strategies that target specific motor impairments (e.g. stroke). The combined use of these tools will lead to increasingly deeper understanding of neural mechanisms of motor control. A key requirement when combining these data acquisition systems is fine temporal correspondence between the various data streams. This protocol describes a multifunctional system&#8217;s overall connectivity, intersystem signaling, and the temporal synchronization of recorded data. Synchronization of the component systems is primarily accomplished through the use of a customizable circuit, readily made with off the shelf components and minimal electronics assembly skills.

Synchronization of the numerous data streams in this setup allows one to record the kinematics, continuous muscle activity (EMG), and instantaneous neuromuscular activity (MEPs) that occur during movements of the upper limb. Repeated trials of a given movement are required to reconstruct MEP response profiles over an entire movement. Figure 4 displays data collected from one subject. Figure 4A shows an example of these data streams during a single trial with the corresponding synchroniza...

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Multifunctional Setup for Studying Human Motor Control Using Transcranial Magnetic Stimulation, Electromyography, Motion Capture, and Virtual Reality

Transcranial magnetic stimulation, electromyography, and 3D motion capture are commonly used non-invasive techniques for investigating neuromuscular function in humans. In this paper, we describe a protocol that synchronously samples data generated by all three of these tools along with the unique addition of virtual reality stimulus presentation and feedback.

The study of neuromuscular control of movement in humans is accomplished with numerous technologies. Non-invasive methods for investigating neuromuscular ...

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Behavior

10.8K Views.  West Virginia University. Transcranial magnetic stimulation, electromyography, and 3D motion capture are commonly used non-invasive techniques for investigating neuromuscular function in humans. In this paper, we describe a protocol that synchronously samples data generated by all three of these tools along with the unique addition of virtual reality stimulus presentation and feedback.

Video: Multifunctional Setup for Studying Human Motor Control Using Transcranial Magnetic Stimulation, Electromyography, Motion Capture, and Virtual Reality

Stimulating the Lip Motor Cortex with Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) has proven to be a useful tool in investigating the role of the articulatory motor cortex in speech perception. Researchers have used single-pulse and repetitive TMS to stimulate the lip representation in the motor cortex. The excitability of the lip motor representation can be investigated by applying single TMS pulses over this cortical area and recording TMS-induced motor evoked potentials (MEPs) via electrodes attached to the lip muscles (electromyography; EMG). Larger MEPs reflect increased cortical excitability. Studies have shown that excitability increases during listening to speech as well as during&#160;viewing speech-related movements. TMS can be used also to disrupt the lip motor representation. A 15-min train of low-frequency sub-threshold repetitive stimulation has been shown to suppress motor excitability for a further 15-20 min. This TMS-induced disruption of the motor lip representation impairs subsequent performance in demanding speech perception tasks and modulates auditory-cortex responses to speech sounds. These findings are consistent with the suggestion that the motor cortex contributes to speech perception. This article describes how to localize the lip representation in the motor cortex and how to define the appropriate stimulation intensity for carrying out both single-pulse and repetitive TMS experiments.

Transcranial magnetic stimulation (TMS) has proven to be a useful tool in investigating the role of the articulatory motor cortex in speech perception.&#160; This article describes how to record motor evoked potentials (MEPs) from the lip muscles and how to disrupt the motor lip representation using repetitive TMS.

Transcranial magnetic stimulation (TMS) has proven to be a useful tool in investigating the role of the articulatory motor cortex in speech perception. ...

Transcranial Direct Current Stimulation and Simultaneous  Functional Magnetic Resonance Imaging

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that uses weak electrical currents administered to the scalp to manipulate cortical excitability and, consequently, behavior and brain function. In the last decade, numerous studies have addressed short-term and long-term effects of tDCS on different measures of behavioral performance during motor and cognitive tasks, both in healthy individuals and in a number of different patient populations. So far, however, little is known about the neural underpinnings of tDCS-action in humans with regard to large-scale brain networks. This issue can be addressed by combining tDCS with functional brain imaging techniques like functional magnetic resonance imaging (fMRI) or electroencephalography (EEG).
In particular, fMRI is the most widely used brain imaging technique to investigate the neural mechanisms underlying cognition and motor functions. Application of tDCS during fMRI allows analysis of the neural mechanisms underlying behavioral tDCS effects with high spatial resolution across the entire brain. Recent studies using this technique identified stimulation induced changes in task-related functional brain activity at the stimulation site&#160;and also in more distant brain regions, which were associated with behavioral improvement. In addition, tDCS administered during resting-state fMRI allowed identification of widespread changes in whole brain functional connectivity.
Future studies using this combined protocol should yield new insights into the mechanisms of tDCS action in health and disease and new options for more targeted application of tDCS in research and clinical settings. The present manuscript describes this novel technique in a step-by-step fashion, with a focus on technical aspects of tDCS administered during fMRI.

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique. It has successfully been used in basic research and clinical settings to modulate brain function in humans. This article describes the implementation of tDCS and simultaneous functional magnetic resonance imaging (fMRI), to investigate the neural basis of tDCS effects.

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that uses weak electrical currents administered to the scalp ...

Transcranial Magnetic Stimulation for Investigating Causal Brain-behavioral Relationships and their Time Course

Transcranial magnetic stimulation (TMS) is a safe, non-invasive brain stimulation technique that uses a strong electromagnet in order to temporarily disrupt information processing in a brain region, generating a short-lived &#8220;virtual lesion.&#8221; Stimulation that interferes with task performance indicates that the affected brain region is necessary to perform the task normally. In other words, unlike neuroimaging methods such as functional magnetic resonance imaging (fMRI) that indicate correlations between brain and behavior, TMS can be used to demonstrate causal brain-behavior relations. Furthermore, by varying the duration and onset of the virtual lesion, TMS can also reveal the time course of normal processing. As a result, TMS has become an important tool in cognitive neuroscience. Advantages of the technique over lesion-deficit studies include better spatial-temporal precision of the disruption effect, the ability to use participants as their own control subjects, and the accessibility of participants. Limitations include concurrent auditory and somatosensory stimulation that may influence task performance, limited access to structures more than a few centimeters from the surface of the scalp, and the relatively large space of free parameters that need to be optimized in order for the experiment to work. Experimental designs that give careful consideration to appropriate control conditions help to address these concerns. This article illustrates these issues with TMS results that investigate the spatial and temporal contributions of the left supramarginal gyrus (SMG) to reading.

Transcranial magnetic stimulation (TMS) is a technique for non-invasively disrupting neural information processing and measuring its effect on behavior. When TMS interferes with a task, it indicates that the stimulated brain region is necessary for normal task performance, allowing one to systematically relate brain regions to cognitive functions.

Transcranial magnetic stimulation (TMS) is a safe, non-invasive brain stimulation technique that uses a strong electromagnet in order to temporarily ...

Neuronavigation-guided Repetitive Transcranial Magnetic Stimulation for Aphasia

Repetitive transcranial magnetic stimulation (rTMS) is widely used for several neurological conditions, as it has gained acknowledgement for its potential therapeutic effects. Brain excitability is non-invasively modulated by rTMS, and rTMS to the language areas has proved its potential effects on treatment of aphasia. In our protocol, we aim to artificially induce virtual aphasia in healthy subjects by inhibiting Brodmann area 44 and 45 using neuronavigational TMS (nTMS), and F3 of the International 10-20 EEG system for conventional TMS (cTMS). To measure the degree of aphasia, changes in reaction time to a picture naming task pre- and post-stimulation are measured and compare the delay in reaction time between nTMS and cTMS. Accuracy of the two TMS stimulation methods is compared by averaging the Talairach coordinates of the target and the actual stimulation. Consistency of stimulation is demonstrated by the error range from the target. The purpose of this study is to demonstrate use of nTMS and to describe the benefits and limitations of the nTMS compared to those of cTMS.

This study is designed to test the hypothesis that neuronavigational system-guided transcranial magnetic stimulation has higher accuracy for targeting the intended target as demonstrated by eliciting a greater degree of virtual aphasia in healthy subjects, measured by delay in reaction time to picture naming.

Repetitive transcranial magnetic stimulation (rTMS) is widely used for several neurological conditions, as it has gained acknowledgement for its potential ...

Substantiating Appropriate Motion Capture Techniques for the Assessment of Nordic Walking Gait and Posture in Older Adults

Nordic walking (NW) has become a safe and simple form of exercise in recent years, and in studying this gait pattern, various data collection techniques have been employed, each with positives and negatives. The aim was to determine the effect of NW on older adult gait and posture and to determine optimal use of different data collection systems in both short and long duration analysis. Gait and posture during NW and normal walking were assessed in 17 healthy older adults (age: 69 &#177; 7.3). Participants performed two trials of 6 Minute Walk Tests (6MWT) (1 with poles (WP) and 1 without poles (NP)) and 6 trials of a 5m walk (3 WP and 3 NP). Motion was recorded using two systems, a 6-sensor accelerometry system and an 8-camera 3-dimensional motion capture system, in order to quantify spatial-temporal, kinematic, and kinetic parameters.
With both systems, participants demonstrated increased stride length and double support and decreased gait speed and cadence WP compared to NP (p &#60;0.05). Also, with motion capture, larger single support time was found WP (p &#60;0.05). With 3-D capture, smaller hip power generation and moments of force were found at heel contact and pre-swing as well as smaller knee power absorption at heel contact, pre-swing, and terminal swing WP compared to NP, when assessed over one cycle (p &#60;0.05). Also, WP yielded smaller moments of force at heel contact and terminal swing along with larger moments at mid-stance of a gait cycle (p &#60;0.05). No changes were found for posture.
NW seems appropriate for promoting a normal gait pattern in older adults. Three-dimensional motion capture should primarily be used during short duration gait analysis (i.e. single gait cycle), while accelerometry systems should be primarily employed in instances requiring longer duration analysis such as during the 6MWT.

The aim was to substantiate optimal use of data collection techniques for Nordic walking gait and posture analysis. Three-dimensional motion capture should be used during short duration analysis (i.e. single gait cycle), while accelerometry should be employed for longer duration analysis (i.e. repeated cycles) like a 6 Minute Walk Test.

Nordic walking (NW) has become a safe and simple form of exercise in recent years, and in studying this gait pattern, various data collection techniques ...

Simultaneous Transcranial Alternating Current Stimulation and Functional Magnetic Resonance Imaging

Transcranial alternating current stimulation (tACS) is a promising tool for noninvasive investigation of brain oscillations. TACS employs frequency-specific stimulation of the human brain through current applied to the scalp with surface electrodes. Most current knowledge of the technique is based on behavioral studies; thus, combining the method with brain imaging holds potential to better understand the mechanisms of tACS. Because of electrical and susceptibility artifacts, combining tACS with brain imaging can be challenging, however, one brain imaging technique that is well suited to be applied simultaneously with tACS is functional magnetic resonance imaging (fMRI). In our lab, we have successfully combined tACS with simultaneous fMRI measurements to show that tACS effects are state, current, and frequency dependent, and that modulation of brain activity is not limited to the area directly below the electrodes. This article describes a safe and reliable setup for applying tACS simultaneously with visual task fMRI studies, which can lend to understanding oscillatory brain function as well as the effects of tACS on the brain.

Transcranial alternating current stimulation (tACS) is a promising tool for noninvasive investigation of brain oscillations, though its effects are not completely understood. This article describes a safe and reliable setup for applying tACS simultaneously with functional magnetic resonance imaging, which can increase understanding oscillatory brain function and effects of tACS.

Transcranial alternating current stimulation (tACS) is a promising tool for noninvasive investigation of brain oscillations. TACS employs ...

Using Virtual Reality to Transfer Motor Skill Knowledge from One Hand to Another

As far as acquiring motor skills is concerned, training by voluntary physical movement is superior to all other forms of training (e.g. training by observation or passive movement of trainee&#39;s hands by a robotic device). This obviously presents a major challenge in the rehabilitation of a paretic limb since voluntary control of physical movement is limited. Here, we describe a novel training scheme we have developed that has the potential to circumvent this major challenge. We exploited the voluntary control of one hand and provided real-time movement-based manipulated sensory feedback as if the other hand is moving. Visual manipulation through virtual reality (VR) was combined with a device that yokes left-hand fingers to passively follow right-hand voluntary finger movements. In healthy subjects, we demonstrate enhanced within-session performance gains of a limb in the absence of voluntary physical training. Results in healthy subjects suggest that training with the unique VR setup might also be beneficial for patients with upper limb hemiparesis by exploiting the voluntary control of their healthy hand to improve rehabilitation of their affected hand.

We describe a novel virtual-reality based setup which exploits voluntary control of one hand to improve motor-skill performance in the other (non-trained) hand. This is achieved by providing real-time movement-based sensory feedback as if the non-trained hand is moving. This new approach may be used to enhance rehabilitation of patients with unilateral hemiparesis.

As far as acquiring motor skills is concerned, training by voluntary physical movement is superior to all other forms of training (e.g. training by ...

Measuring the Kinematics of Daily Living Movements with Motion Capture Systems in Virtual Reality

The inability to complete instrumental activities of daily living (IADL) is a precursor to various neuropsychological diseases. Questionnaire-based assessments of IADL are easy to use but prone to subjective bias. Here, we describe a novel virtual reality (VR) test to assess two complex IADL tasks: handling financial transactions and using public transportation. While a participant performs the tasks in a VR setting, a motion capture system traces the position and orientation of the dominant hand and head in a three-dimensional Cartesian coordinate system. Kinematic raw data are collected and converted into &#39;kinematic performance measures,&#39; i.e., motion trajectory, moving distance, and time to completion. Motion trajectory is the path of a particular body part (e.g., dominant hand or head) in space. Moving distance refers to the total distance of the trajectory, and time to completion is how long it took to complete an IADL task. These kinematic measures could discriminate patients with cognitive impairment from healthy controls. The development of this kinematic measuring protocol allows detection of early IADL-related cognitive impairments.

We designed a virtual reality test to assess instrumental activities of daily living (IADL) with a motion capture system. We propose a detailed kinematic analysis to interpret the participant&#39;s various movements, including trajectory, moving distance, and time to completion to evaluate IADL capabilities.

The inability to complete instrumental activities of daily living (IADL) is a precursor to various neuropsychological diseases. Questionnaire-based ...

A Networked Desktop Virtual Reality Setup for Decision Science and Navigation Experiments with Multiple Participants

Investigating the interactions among multiple participants is a challenge for researchers from various disciplines, including the decision sciences and spatial cognition. With a local area network and dedicated software platform, experimenters can efficiently monitor the behavior of the participants that are simultaneously immersed in a desktop virtual environment and digitalize the collected data. These capabilities allow for experimental designs in spatial cognition and navigation research that would be difficult (if not impossible) to conduct in the real world. Possible experimental variations include stress during an evacuation, cooperative and competitive search tasks, and other contextual factors that may influence emergent crowd behavior. However, such a laboratory requires maintenance and strict protocols for data collection in a controlled setting. While the external validity of laboratory studies with human participants is sometimes questioned, a number of recent papers suggest that the correspondence between real and virtual environments may be sufficient for studying social behavior in terms of trajectories, hesitations, and spatial decisions. In this article, we describe a method for conducting experiments on decision-making and navigation with up to 36 participants in a networked desktop virtual reality setup (i.e., the Decision Science Laboratory or DeSciL). This experiment protocol can be adapted and applied by other researchers in order to set up a networked desktop virtual reality laboratory.

This paper describes a method for conducting multi-user experiments on decision-making and navigation using a networked computer laboratory.

Investigating the interactions among multiple participants is a challenge for researchers from various disciplines, including the decision sciences and ...

Virtual Reality Experiments with Physiological Measures

Virtual reality (VR) experiments are increasingly employed because of their internal and external validity compared to real-world observation and laboratory experiments, respectively. VR is especially useful for geographic visualizations and investigations of spatial behavior. In spatial behavior research, VR provides a platform for studying the relationship between navigation and physiological measures (e.g., skin conductance, heart rate, blood pressure). Specifically, physiological measures allow researchers to address novel questions and constrain previous theories of spatial abilities, strategies, and performance. For example, individual differences in navigation performance may be explained by the extent to which changes in arousal mediate the effects of task difficulty. However, the complexities in the design and implementation of VR experiments can distract experimenters from their primary research goals and introduce irregularities in data collection and analysis. To address these challenges, the Experiments in Virtual Environments (EVE) framework includes standardized modules such as participant training with the control interface, data collection using questionnaires, the synchronization of physiological measurements, and data storage. EVE also provides the necessary infrastructure for data management, visualization, and evaluation. The present paper describes a protocol that employs the EVE framework to conduct navigation experiments in VR with physiological sensors. The protocol lists the steps necessary for recruiting participants, attaching the physiological sensors, administering the experiment using EVE, and assessing the collected data with EVE evaluation tools. Overall, this protocol will facilitate future research by streamlining the design and implementation of VR experiments with physiological sensors.

Virtual reality (VR) experiments can be difficult to implement and require meticulous planning. This protocol describes a method for the design and implementation of VR experiments that collect physiological data from human participants. The Experiments in Virtual Environments (EVE) framework is employed to accelerate this process.