Name: non-invasive electrical brain stimulation montages for modulation of human motor function
Uploaded: 2016-02-04T13:00:00
Description: Watch this Scientific Journal Video about Non-Invasive Electrical Brain Stimulation Montages for Modulation of Human Motor Function at JoVE.com

MC and JR are supported by the German Research Foundation (DFG RE 2740/3-1).

Ethics statement: Human studies require written informed consent of participants before study entry. Obtain approval by the relevant ethics committee before recruitment of participants. Make sure studies are in accordance with the Declaration of Helsinki. The representative findings reported here (Figure 4) are based on a study performed in accordance with the Declaration of Helsinki amended by the 59th WMA General Assembly, Seoul, October 2008 and approved by the local Ethics Committee of the Uni...

This protocol describes typical materials and procedural steps for modulation of hand motor function and skill learning using NEBS, specifically unilateral and bilateral M1 stimulation for anodal tDCS, and unilateral tRNS. Before choosing a particular NEBS protocol for a human motor system study, e.g., in the context of motor learning, methodological aspects (safety, tolerability, blinding) as well as conceptual aspects (montage or current type specific effects on a particular brain region) need to be taken into...

Non-invasive electrical brain stimulation (NEBS), the administration of electrical currents to the brain through the intact skull, can modify brain function and behavior1-3. To optimize the therapeutic potential of NEBS strategies understanding the underlying mechanisms leading to neurophysiological and behavioral effects is still needed. Standardization of application across different laboratories and full transparency of stimulation procedures provides the basis for comparability of data which supports reliable interpretation of results and evaluation of the proposed mechanisms of action. Transcranial direct current stimulation (tDCS) or transcranial alternating current stimulation (tACS) differ by parameters of the applied electrical current: tDCS consists of an unidirectional constant current flow between two electrodes (anode and cathode)2-6 while tACS uses an alternating current applied at a specific frequency7. Transcranial random noise stimulation (tRNS) is a special form of tACS that uses an alternating current applied at random frequencies (e.g., 100-640 Hz) resulting in quickly varying stimulation intensities and removing polarity-related effects4,6,7. Polarity is only of relevance if the stimulation setting includes a stimulation offset, e.g., noise spectrum randomly changing around a +1 mA baseline intensity (usually not used). For the purpose of this article, we will focus on work using tDCS and tRNS effects on the motor system, closely following a recent publication from our lab6.
The underlying mechanisms of action of tRNS are even less understood than of tDCS but likely different from the latter. Theoretically, in the conceptual framework of stochastic resonance tRNS introduces stimulation-induced noise to a neuronal system which may provide a signal processing benefit by altering the signal-to-noise ratio4,8,9. TRNS may predominantly amplify weaker signals and could thus optimize task-specific brain activity (endogenous noise9). Anodal tDCS increases cortical excitability indicated by alteration of the spontaneous neuronal firing rate10 or increased motor evoked potential (MEP) amplitudes2 with the effects outlasting the stimulation duration for minutes to hours. Long-lasting increases in synaptic efficacy known as long-term potentiation are thought to contribute to learning and memory. Indeed, anodal tDCS enhances synaptic efficacy of motor cortical synapses repeatedly activated by a weak synaptic input11. In accordance, improved motor function/skill acquisition is often revealed only if stimulation is co-applied with motor training11-13, also suggesting synaptic co-activation as a prerequisite of this activity-dependent process. Nevertheless, causality between increases in cortical excitability (increase in firing rate or MEP amplitude) on one hand and improved synaptic efficacy (LTP or behavioral function such as motor learning) on the other hand has not been demonstrated.
NEBS applied to the primary motor cortex (M1) has attracted increasing interest as safe and effective method to modulate human motor function1. Neurophysiological effects and behavioral outcome may depend on the stimulation strategy (e.g., tDCS polarity or tRNS), electrode size and montage4-6,14,15. Aside from subject-inherent anatomical and physiological factors the electrode montage significantly influences electric field distribution and may result in different patterns of current spreading within the cortex16-18. In addition to the intensity of the applied current the size of the electrodes determines the current density delivered3. Common electrode montages in human motor system studies include (Figure 1): 1) anodal tDCS as unilateral M1 stimulation with the anode positioned on the M1 of interest and the cathode positioned on the contralateral forehead; the basic idea of this approach is upregulation of excitability in the M1 of interest6,13,19-22; 2) anodal tDCS as bilateral M1 stimulation (also referred to as &#34;bihemispheric&#34; or &#34;dual&#34; stimulation) with the anode positioned on the M1 of interest and the cathode positioned on the contralateral M15,6,14,23,24; the basic idea of this approach is maximizing stimulation benefits by upregulation of excitability in the M1 of interest while downregulating excitability in the opposite M1 (i.e., modulation of interhemispheric inhibition between the two M1s); 3) For tRNS, only the above mentioned unilateral M1 stimulation montage has been investigated4,6; with this montage excitability enhancing effects of tRNS have been found for the frequency spectrum of 100-640 Hz4. The choice of brain stimulation strategy and electrode montage represents a critical step for an efficient and reliable use of NEBS in clinical or research settings. Here these three NEBS procedures are described in detail as used in human motor system studies and methodological and conceptual aspects are discussed. Materials for unilateral or bilateral tDCS and unilateral tRNS are the same (Figure 2).
<img alt="Figure 1" src="/files/ftp_upload/53367/53367fig1.jpg" /> 
Figure 1.&#160;Electrode montages and current direction for distinct NEBS strategies.&#160;(A) For unilateral anodal transcranial direct current stimulation (tDCS), the anode is centered over the primary motor cortex of interest and the cathode positioned over the contralateral supra-orbital area. (B) For bilateral motor cortex stimulation, anode and cathode are located each over one motor cortex. The position of the anode determines the motor cortex of interest for anodal tDCS. (C) For unilateral transcranial random noise stimulation (tRNS), one electrode is located over the motor cortex and the other electrode over the contralateral supra-orbital area. The current flow between electrodes is indicated by the black arrow. Anode (+, red), cathode (-, blue), Alternating current (+/-, green). <a href="https://www.jove.com/files/ftp_upload/53367/53367fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

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			<td>8x5m, textile elasticity</td>
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			<td height="21" style="height:21px;width:301px;">Magnetic stimulator</td>
			<td style="width:271px;">Magstim</td>
			<td style="width:119px;">3010-00</td>
			<td>Magstim 200</td>
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			<td>e.g., Natus Medical Inc. Viking 4&#160;</td>
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			<td>e.g., Natus Medical Inc. Viking 4&#160;</td>
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			<td height="21" style="height:21px;width:301px;">Cable for EMG signal transmission</td>
			<td>e.g., Natus Medical Inc. Viking 4</td>
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			<td>AD converter</td>
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			<td height="42" style="height:42px;width:301px;">Computer for signal recording and offline analysis</td>
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			<td height="21" style="height:21px;width:301px;">Signal 4.0.9</td>
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			<td>Software</td>
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			<td height="21" style="height:21px;width:301px;">non-permanent skin marker</td>
			<td style="width:271px;">Edding</td>
			<td style="width:119px;">8020</td>
			<td>1 mm, blue</td>
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non-invasive electrical brain stimulation montages for modulation of human motor function

Non-invasive electrical brain stimulation (NEBS) is used to modulate brain function and behavior, both for research and clinical purposes. In particular, NEBS can be applied transcranially either as direct current stimulation (tDCS) or alternating current stimulation (tACS). These stimulation types exert time-, dose- and in the case of tDCS polarity-specific effects on motor function and skill learning in healthy subjects. Lately, tDCS has been used to augment the therapy of motor disabilities in patients with stroke or movement disorders. This article provides a step-by-step protocol for targeting the primary motor cortex with tDCS and transcranial random noise stimulation (tRNS), a specific form of tACS using an electrical current applied randomly within a pre-defined frequency range. The setup of two different stimulation montages is explained. In both montages the emitting electrode (the anode for tDCS) is placed on the primary motor cortex of interest. For unilateral motor cortex stimulation the receiving electrode is placed on the contralateral forehead while for bilateral motor cortex stimulation the receiving electrode is placed on the opposite primary motor cortex. The advantages and disadvantages of each montage for the modulation of cortical excitability and motor function including learning are discussed, as well as safety, tolerability and blinding aspects.

To investigate the effects of NEBS on the human motor system it is important to consider appropriate outcome measures. One advantage of the motor system is the accessibility of the cortical representations by electrophysiological tools. Motor evoked potentials are frequently used as an indicator of motor cortical excitability. After application of 9 or more minutes of anodal tDCS at a current density of 29 &#181;A/cm2, motor cortical excitability is increased for at least 30 mi...

Watch this Scientific Journal Video about Non-Invasive Electrical Brain Stimulation Montages for Modulation of Human Motor Function at JoVE.com

Non-Invasive Electrical Brain Stimulation Montages for Modulation of Human Motor Function

Non-invasive electrical brain stimulation can modulate cortical function and behavior, both for research and clinical purposes. This protocol describes different brain stimulation approaches for modulation of the human motor system.

Non-invasive electrical brain stimulation (NEBS) is used to modulate brain function and behavior, both for research and clinical purposes. In particular, ...

The overall goal of this procedure is to demonstrate the localization of the primary motor cortex, and correct placement of electrical brain stimulation electrodes, to modulate the motor system. This method can help answer key questions in the field of neuroplasticity, through the targeted modulation of brain networks that improve motor functions, or counteract motor disabilities. The main advantage of non-evasive electrical brain stimulation is that it is easy to administer even as a bedside technique, without inducing pain or discomfort.This method of brain stimulation can provide insight into the function of the motor system. It can also be applied to other regions of interest, such as the pre-frontal cortex, or the visual cortex. Visual demonstration of the localization of target cortical areas and electrode placement are crucial for the success of these experiments.Otherwise, electrical current flow may not reach the intended brain areas, resulting in a lack of effect, or unexpected findings. Begin by asking the participant to sit comfortably in the chair. Clean the participant's skin by rubbing preparation paste in the regions of the hand where electrodes will be placed.Remove excess with a clean gauze pad. Attach the electromyography, or EMG, surface electrodes in a belly-tendon montage, on the hand muscle of interest, and connect a ground electrode. Then, turn on the magnetic stimulator and charge the capacitor by pressing the corresponding charge button.Place a figure of eight TMS coil on the participant's scalp on the motor cortex region. Hold the TMS coil at a 45 to 50 degree angle, referenced to the inter-hemispheric fissure, with the handle oriented backwards. When the magnetic stimulator is charged, discharge the stimulator by either pressing the trigger button, by stepping on the foot switch, or automatically with a software program.Next, start with a low stimulation intensity, and watch for motor evoked potentials, or MEP's, visible on the EMG amplifier. If no MEP is visible, increase the stimulation intensity, until an MEP is clearly present. Repeat stimulation by pressing the trigger button.Move the coil radially, in one centimeter steps, around the initially stimulated site, to find the spot with the largest MEP response, following the application of single TMS pulses. From there, start moving the coil again to secure the hot spot. Finally, mark the hot spot position, and coil orientation with a non-permanent skin marker.Connect cables to rubber electrodes, and place the electrodes inside the sponge bags. Ensure that the electrode size and sponge bag size match. Soak sponge bags on both sides with isotonic sodium chloride solution, but avoid excessive soaking to prevent salt bridges, or dripping onto the volunteer.Next, find the head markings indicating the motor cortical hot spot, and separate the hair around the area. To improve conductance, clean the skin before electrode placement with a swab soaked with 40 to 50 percent alcohol, or skin preparation paste. Remove excess with a swab, and clean the area again with isotonic sodium chloride solution.Dry the area afterwards. Place one electrode on the head marking for the motor cortex area of interest, and keep the sponge in direct contact with the skin as much as possible. For unilateral stimulation, place the second electrode over the contralateral supra-orbital area.Alternatively, for bilateral stimulation, place the second electrode on the opposite motor cortex, following the head marking ipsilateral to the limb used in the study. Place all of the electrode cables towards the participants back, to avoid disturbance during stimulation, and to ease connection to the non-invasive electrical brain stimulation, or any BS device. Then, cover the head twice, with an elastic bandage, circularly in the mediolateral direction, to stabilize the M1 electrode.Use the remaining bandage to cover the head circularly in the anterior posterior direction, to stabilize both electrodes. Use adhesive tape to fix the end of the bandage, and secure the cables with adhesive tape on the participant's neck, or shirt. Finally, connect the electrode cables to any BS device.Begin by switching on any BS device. Adjust the any BS device settings, regarding stimulation type, intensity, duration, ramping up and down, and frequency spectrum for transcranial random noise stimulation. Next, inform the participant about potential side effects associated with any BS.Then start the stimulation, and check for continuity of stimulation, during ramping up, and throughout the session.If any BS is co-applied with the execution of a motor task, start the testing after stimulation is ramped up, and after the participant is feeling comfortable with stimulation. Finally, after the stimulation session is complete, disinfect the electrodes and sponges with 40 to 50 percent alcohol. Then thoroughly rinse in water, and let the materials dry before storing.This protocol describes multiple approaches for non-invasive electrical brain stimulation, for modulation of the human motor system. Here the time course of cortical excitability is shown over the course of 90 minutes after stimulation of the primary motor cortex. Note that TRNS exerts similar effects on cortical excitability compared to TDCS.Within three days of motor training, motor skill increases significantly over time, in the Sham control group, and is augmented further by each any BS strategy. After watching this video, you should have a good understanding of how to locate the primary motor cortex by TMS, and place electrodes for the different any BS montages. Once mastered, this technique can be completed in 10 to 15 minutes, if it is performed properly.Don't forget that working with magnetic and electrical brain stimulation can be harmful if used improperly, and safety screening of participants should always be done before performing this procedure.

non-invasive-electrical-brain-stimulation-montages-for-modulation

Research

JoVE Journal

Behavior

Simultaneous Scalp Electroencephalography (EEG), Electromyography (EMG), and Whole-body Segmental Inertial Recording for Multi-modal Neural Decoding

Recent studies support the involvement of supraspinal networks in control of bipedal human walking. Part of this evidence encompasses studies, including our previous work, demonstrating that gait kinematics and limb coordination during treadmill walking can be inferred from the scalp electroencephalogram (EEG) with reasonably high decoding accuracies. These results provide impetus for development of non-invasive brain-machine-interface (BMI) systems for use in restoration and/or augmentation of gait- a primary goal of rehabilitation research. To date, studies examining EEG decoding of activity during gait have been limited to treadmill walking in a controlled environment. However, to be practically viable a BMI system must be applicable for use in everyday locomotor tasks such as over ground walking and turning. Here, we present a novel protocol for non-invasive collection of brain activity (EEG), muscle activity (electromyography (EMG)), and whole-body kinematic data (head, torso, and limb trajectories) during both treadmill and over ground walking tasks. By collecting these data in the uncontrolled environment insight can be gained regarding the feasibility of decoding unconstrained gait and surface EMG from scalp EEG.

Simultaneous Scalp Electroencephalography EEG, Electromyography EMG, and Whole-body Segmental Inertial Recording for Multi-modal Neural Decoding

Development of an effective brain-machine-interface (BMI) system for restoration and rehabilitation of bipedal locomotion requires accurate decoding of user's intent. Here we present a novel experimental protocol and data collection technique for simultaneous non-invasive acquisition of neural activity, muscle activity, and whole-body kinematics during various locomotion tasks and conditions.

Recent  studies support the involvement of supraspinal networks in control of bipedal  human walking. Part of this evidence  encompasses studies, ...

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 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 ...

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.

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 ...

A Novel Experimental and Analytical Approach to the Multimodal Neural Decoding of Intent During Social Interaction in Freely-behaving Human Infants

Understanding typical and atypical development remains one of the fundamental questions in developmental human neuroscience. Traditionally, experimental paradigms and analysis tools have been limited to constrained laboratory tasks and contexts due to technical limitations imposed by the available set of measuring and analysis techniques and the age of the subjects. These limitations severely limit the study of developmental neural dynamics and associated neural networks engaged in cognition, perception and action in infants performing &#8220;in action and in context&#8221;. This protocol presents a novel approach to study infants and young children as they freely organize their own behavior, and its consequences in a complex, partly unpredictable and highly dynamic environment. The proposed methodology integrates synchronized high-density active scalp electroencephalography (EEG), inertial measurement units (IMUs), video recording and behavioral analysis to capture brain activity and movement non-invasively in freely-behaving infants. This setup allows for the study of neural network dynamics in the developing brain, in action and context, as these networks are recruited during goal-oriented, exploration and social interaction tasks.

This protocol presents a novel methodology for the neural decoding of intent from freely-behaving infants during unscripted social interaction with an actor. Neural activity is acquired using non-invasive high-density active scalp electroencephalography (EEG). Kinematic data is collected with inertial measurement units and supplemented with synchronized video recording.

Understanding typical and atypical development remains one of the fundamental questions in developmental human neuroscience. Traditionally, experimental ...

A Novel Approach to Assess Motor Outcome of Deep Brain Stimulation Effects in the Hemiparkinsonian Rat: Staircase and Cylinder Test

Deep brain stimulation of the subthalamic nucleus is an effective treatment option for Parkinson&#39;s disease. In our lab we established a protocol to screen different neurostimulation patterns in hemiparkinsonian (unilateral lesioned) rats. It consists of creating a unilateral Parkinson&#39;s lesion by injecting 6-hydroxydopamine (6-OHDA) into the right medial forebrain bundle, implanting chronic stimulation electrodes into the subthalamic nucleus and evaluating motor outcomes at the end of 24 hr periods of cable-bound external neurostimulation. The stimulation was conducted with constant current stimulation. The amplitude was set 20% below the individual threshold for side effects. The motor outcome evaluation was done by the assessment of spontaneous paw use in the cylinder test according to Shallert and by the assessment of skilled reaching in the staircase test according to Montoya. This protocol describes in detail the training in the staircase box, the cylinder test, as well as the use of both in hemiparkinsonian rats. The use of both tests is necessary, because the staircase test seems to be more sensitive for fine motor skill impairment and exhibits greater sensitivity to change during neurostimulation. The combination of the unilateral Parkinson model and the two behavioral tests allows the assessment of different stimulation parameters in a standardized way.

Deep brain stimulation (DBS) is an effective treatment option for Parkinson's disease. We established a study design to screen novel stimulation paradigms in rats. The protocol describes the use of the staircase test and cylinder test for motor outcome assessment in DBS treated hemiparkinsonian rats.

Deep brain stimulation of the subthalamic nucleus is an effective treatment option for Parkinson&#39;s disease. In our lab we established a protocol to ...

Conscious and Non-conscious Representations of Emotional Faces in Asperger's Syndrome

Several neuroimaging studies have suggested that the low spatial frequency content in an emotional face mainly activates the amygdala, pulvinar, and superior colliculus especially with fearful faces1-3. These regions constitute the limbic structure in non-conscious perception of emotions and modulate cortical activity either directly or indirectly2. In contrast, the conscious representation of emotions is more pronounced in the anterior cingulate, prefrontal cortex, and somatosensory cortex for directing voluntary attention to details in faces3,4. Asperger&#39;s syndrome (AS)5,6 represents an atypical mental disturbance that affects sensory, affective and communicative abilities, without interfering with normal linguistic skills and intellectual ability. Several studies have found that functional deficits in the neural circuitry important for facial emotion recognition can partly explain social communication failure in patients with AS7-9. In order to clarify the interplay between conscious and non-conscious representations of emotional faces in AS, an EEG experimental protocol is designed with two tasks involving emotionality evaluation of either photograph or line-drawing faces. A pilot study is introduced for selecting face stimuli that minimize the differences in reaction times and scores assigned to facial emotions between the pretested patients with AS and IQ/gender-matched healthy controls. Information from the pretested patients was used to develop the scoring system used for the emotionality evaluation. Research into facial emotions and visual stimuli with different spatial frequency contents has reached discrepant findings depending on the demographic characteristics of participants and task demands2. The experimental protocol is intended to clarify deficits in patients with AS in processing emotional faces when compared with healthy controls by controlling for factors unrelated to recognition of facial emotions, such as task difficulty, IQ and gender.

Conscious and Non-conscious Representations of Emotional Faces in Asperger&#039;s Syndrome

An EEG experimental protocol is designed to clarify the interplay between conscious and non-conscious representations of emotional faces in patients with Asperger&#39;s syndrome. The technique suggests that patients with Asperger&#39;s syndrome have deficits in non-conscious representation of emotional faces, but have comparable performance in conscious representation with healthy controls.

Several neuroimaging studies have suggested that the low spatial frequency content in an emotional face mainly activates the amygdala, pulvinar, and ...

Using a Split-belt Treadmill to Evaluate Generalization of Human Locomotor Adaptation

Understanding the mechanisms underlying locomotor learning helps researchers and clinicians optimize gait retraining as part of motor rehabilitation. However, studying human locomotor learning can be challenging. During infancy and childhood, the neuromuscular system is quite immature, and it is unlikely that locomotor learning during early stages of development is governed by the same mechanisms as in adulthood. By the time humans reach maturity, they are so proficient at walking that it is difficult to come up with a sufficiently novel task to study de novo locomotor learning. The split-belt treadmill, which has two belts that can drive each leg at a different speed, enables the study of both short- (i.e., immediate) and long-term (i.e., over minutes-days; a form of motor learning) gait modifications in response to a novel change in the walking environment. Individuals can easily be screened for previous exposure to the split-belt treadmill, thus ensuring that all experimental participants have no (or equivalent) prior experience. This paper describes a typical split-belt treadmill adaptation protocol that incorporates testing methods to quantify locomotor learning and generalization of this learning to other walking contexts. A discussion of important considerations for designing split-belt treadmill experiments follows, including factors like treadmill belt speeds, rest breaks, and distractors. Additionally, potential but understudied confounding variables (e.g., arm movements, prior experience) are considered in the discussion.

We describe a protocol for investigating human locomotor adaptation using the split-belt treadmill, which has two belts that can drive each leg at a different speed. We specifically focus on a paradigm designed to test the generalization of adapted locomotor patterns to different walking contexts (e.g., gait speeds, walking environments).

Understanding the mechanisms underlying locomotor learning helps researchers and clinicians optimize gait retraining as part of motor rehabilitation. ...

Paradigms of Lower Extremity Electrical Stimulation Training After Spinal Cord Injury

Skeletal muscle atrophy, increased adiposity and reduced physical activity are key changes observed after spinal cord injury (SCI) and are associated with numerous cardiometabolic health consequences. These changes are likely to increase the risk of developing chronic secondary conditions and impact the quality of life in persons with SCI. Surface neuromuscular electrical stimulation evoked resistance training (NMES-RT) was developed as a strategy to attenuate the process of skeletal muscle atrophy, decrease ectopic adiposity, improve insulin sensitivity and enhance mitochondrial capacity. However, NMES-RT is limited to only a single muscle group. Involving multiple muscle groups of the lower extremities may maximize the health benefits of training. Functional electrical stimulation-lower extremity cycling (FES-LEC) allows for the activation of 6 muscle groups, which is likely to evoke greater metabolic and cardiovascular adaptation. Appropriate knowledge of the stimulation parameters is key to maximizing the outcomes of electrical stimulation training in persons with SCI. Adopting strategies for long-term use of NMES-RT and FES-LEC during rehabilitation may maintain the integrity of the musculoskeletal system, a pre-requisite for clinical trials aiming to restore walking after injury. The current manuscript presents a combined protocol using NMES-RT prior to FES-LEC. We hypothesize that muscles conditioned for 12 weeks prior to cycling will be capable of generating greater power, cycle against higher resistance and result in greater adaptation in persons with SCI.

Spinal cord injury is a traumatic medical condition that may result in elevated risks of chronic secondary metabolic disorders. Here, we presented a protocol using surface neuromuscular electrical stimulation-resistance training in conjunction with functional electrical stimulation-lower extremities cycling as a strategy to ameliorate several of these medical problems.

Skeletal muscle atrophy, increased adiposity and reduced physical activity are key changes observed after spinal cord injury (SCI) and are associated with ...

A Simple Non-invasive Method for Temporary Knockdown of Upper Limb Proprioception

Proprioception may be the least well measured of all contributors to the neural control of movement. New precise, reliable measures of proprioception are needed for clinical diagnosis of impairment, and to measure outcomes of proprioceptive training. The purpose of this simple, non-invasive method is to temporarily knockdown upper limb proprioception in healthy adults, to an extent that would be useful in the development and testing of upper limb proprioception measures. Knockdown models have two main advantages over studying humans with impaired proprioception: participant availability and the ability to control the extent of impairment across participants. Current published methods of temporary proprioception knockdown of the upper limb, such as ischemic nerve blocks and cryotherapy, are invasive, impractical, or uncomfortable for the participant. Here, vibration over the ulnar groove was used to reduce upper limb proprioception. High frequency vibration may reduce proprioceptive acuity by inhibiting pacinian corpuscle-induced input. The effect of vibration used in this protocol was confirmed using two quantitative measures. This method was simple to administer, comfortable for participants, and practical.

The goal of this protocol is to demonstrate a practical method to temporarily interfere with proprioception in the upper limb of healthy humans.

Proprioception may be the least well measured of all contributors to the neural control of movement. New precise, reliable measures of proprioception are ...