1. Préparation <ol class="lalpha"><li> Pour commencer, obtenir un balayage anatomiques de base de votre sujet. Cela devrait être fait quelques jours avant l&#39;expérience réelle. </li><li> Ensuite, chargez le scan dans votre forfait stéréotaxique sans cadre logiciels. </li><li> Enfin, localiser et cibler vos coordonnées stimulation. Dans ce cas, nous allons cibler le lobule pariétal inférieur gauche. </li></ol> 2. L&#39;analyse initiale <ol class="lalpha"><li> Le jour de l&#39;expérience, votre sujet sera, encore une fois, lancer dans la machine IRM. </li><li> Commencer par une analyse anatomique. </li><li> Ensuite, effectuer trois descentes d&#39;expérimentation fonctionnels. Pour cette expérience, la tâche est assez simple: un point de fixation est présenté dans le champ du sujet central de la vision, et il / elle est tout simplement de regarder passivement. </li></ol> 3. Préparation TMS <ol class="lalpha"><li> Parce que les effets de la SMTr sont transitoires, le temps est de l&#39;essence en combinant TMS et l&#39;IRMf. Il est impératif que vous obtenez le dos sujet dans le scanner dès que possible après la cessation de stimulation. Pour cette raison, vous aurez envie d&#39;utiliser un appareil portable TMS stationnés dans une salle adjacente à ou aussi proche que possible de la numérisation-bay que possible. Dans ce cas, nous utilisons un ordinateur portable mis en place dans une suite d&#39;observation à côté de le scanner. </li><li> Charge de pré-ciblés de votre sujet IRM initiale dans le logiciel de stéréotaxie. </li><li> Enfin, le lien et calibrer votre bobine de stimulation avec l&#39;équipement stéréotaxie - dans ce cas, nous allons aligner une série de capteurs infrarouges pour enregistrer la centralité de la bobine. </li></ol> 4. Détermination des paramètres de TMS <ol class="lalpha"><li> Lorsque le sujet arrive, lui assis / elle confortablement dans un fauteuil. </li><li> Ensuite, calibrer tête de votre sujet avec le matériel sterotaxy. Dans ce cas, nous allons utiliser des capteurs infrarouges pour enregistrer les ancres de positionnement de plusieurs: les deux oreilles, le nez, et le nasion. </li><li> Déterminer le seuil de votre sujet du moteur au repos. </li><li> Si nous voulons pour exciter le cortex du sujet, nous allons mettre la machine TMS à 20 Hz avec une puissance de stimulation du seuil moteur 110%. Si nous voulons empêcher le cortex du sujet, nous allons mettre la machine TMS à 1 Hz à 110% du seuil moteur. Bien que vous aurez envie d&#39;explorer ces deux paramètres dans le cadre d&#39;une étude complète, nous allons seulement regarder une chaîne de 20 Hz SMTr excitateurs dans cet article. </li><li> Enfin, mis en place un modèle de stimulation de deux trains secondes avec 28 secondes de repos. </li></ol> 5. La stimulation TMS <ol class="lalpha"><li> Avant la stimulation, de préparer le sujet pour aller directement dans le TMS suivants scanner. Cela comprend l&#39;enlèvement de métal et de s&#39;assurer que le sujet a utilisé les toilettes. </li><li> Tenir la bobine tangentielle sur le cuir chevelu, l&#39;utilisation de votre équipement stéréotaxie pour localiser et cibler site de stimulation du sujet. </li><li> Allumez le système de la machine serpentin de refroidissement. </li><li> Commencez la stimulation! Pour ce protocole, nous procéderons à 45 trains de stimulation totale. Moins 2 secondes un train avec 28 secondes pauses, nous aurons un temps stim total de 23 minutes. </li></ol> 6. Retour au scanner <ol class="lalpha"><li> Une fois que la stimulation est terminée, il est important d&#39;obtenir l&#39;objet de retour dans le scanner dès que possible. Pour rendre cette transition aussi transparente que possible, s&#39;assurer que votre scanner est préparé et prêt à aller. Notre conseil est d&#39;élever la plate-forme du corps, et de réduire le nombre et la durée de scans localisateur à un strict minimum. </li></ol> 7. Finale de numérisation <ol class="lalpha"><li> Parce que les effets de la SMTr sont transitoires, la session finale de numérisation devrait commencer par les pistes fonctionnelles. Encore une fois, nous allons procéder à trois, six minutes pistes de fixation passive. </li><li> Après les essais expérimentaux sont complets, en finir avec une analyse anatomique. </li></ol> 8. Les résultats représentatifs <img src="/files/ftp_upload/2271/2271fig1.jpg" alt="Figure 1" /> Figure 1. Les données suggèrent que 20 Hz SMTr stimulation du lobule pariétal inférieur gauche, bien que facilitant l&#39;excitabilité locale, agit en diminuant la connectivité fonctionnelle au sein du réseau par défaut.

<ol>
	<li>Raichle, M. E., MacLeod, A. M., Snyder, A. Z., Powers, W. J., Gusnard, D. A., Shulman, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+default+mode+of+brain+function.">A default mode of brain function.</a> Proc. Nat. Acad. Sciences. 98 (2), 676-682 (2001).</li><li>Buckner, R. L., Andrews-Hanna, J. R., Schacter, D. 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+brain's+default+network:+anatomy,+function+and+relevance+to+disease.">The brain's default network: anatomy, function and relevance to disease.</a> Ann. N.Y. Acad. Sci. 1124, 1-38 (2008).</li><li>Raichle, M. E., Snyder, A. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+default+mode+of+brain+function:+a+brief+history+of+an+evolving+idea.">A default mode of brain function: a brief history of an evolving idea.</a> Neuroimage. 37 (4), 1083-1090 (2007).</li><li>Whitfield-Gabrieli, S., Thermenos, H. W., Milanovic, S., Tsuang, M. T., Faraone, S. V., McCarley, R. W., Shenton, M. E., Green, A. I., Nieto-Castanon, A., LaViolette, P., Wojcik, J., Gabrieli, J. D., Sidman, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperactivity+and+hyperconnectivity+of+the+default+network+in+schizophrenia+and+in+first-degreerelatives+of+persons+with+schizophrenia.">Hyperactivity and hyperconnectivity of the default network in schizophrenia and in first-degreerelatives of persons with schizophrenia.</a> Proc. Nat. Acad. Sciences. 106 (4), 1279-1284 (2009).</li><li>Pomarol-Clotet, E., Salvardor, R., Sarro, S., Gomar, J., Vila, F., Martinez, A., Guerrrero, A., Ortiz-Gil, J., Sans-Sansa, B., Capdevila, A., Cebamanos, J. M., McKenna, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Failure+to+deactivate+the+prefrontal+cortex+in+schizophrenia:+dysfunction+of+the+default+mode+network?.">Failure to deactivate the prefrontal cortex in schizophrenia: dysfunction of the default mode network?.</a> Psychol Med. 38 (8), 1185-1193 (2008).</li><li>Garrity, A. G., Pearlson, G. D., McKiernan, K., Lloyd, D., Kiehl, K. A., Calhoun, V. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aberrant+"default+mode"+functional+connectivity+in+schizophrenia.">Aberrant "default mode" functional connectivity in schizophrenia.</a> American Journal of Psychiatry. 164, 450-457 (2007).</li><li>Kennedy, D. P., Redcay, E., Courchesne, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Failing+to+deactivate:+Resting+functional+abnormalities+in+autism.">Failing to deactivate: Resting functional abnormalities in autism.</a> Proc. Nat. Acad. Sciences. 103 (21), 8275-8280 (2007).</li><li>c Buckner, R. L., Snyder, A. Z., Shannon, B. J., LaRossa, G., Sachs, R., Fotenos, A. F., Sheline, Y. I., Klunk, W. E., Mathis, C. A., Morris, J. C., Mintun, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular,+structural,+and+functional+characterizations+of+Alzheimer's+disease:+evidence+for+a+relationship+between+default+activity,+amyloid,+and+memory.">Molecular, structural, and functional characterizations of Alzheimer's disease: evidence for a relationship between default activity, amyloid, and memory.</a> Journal of Neuroscience. 34, 7709-7717 (2005).</li><li>Pascual-Leone, A., Davey, M., Wassermann, E. M., Rothwell, J., Puri, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook of Transcranial Magnetic Stimulation. , (2002).</li></ol>

<p class="jove_content"&gt; Quand il mène une TMS déconnecté / expérience IRM, sans doute le facteur le plus important concerne la transition rapide et sans effort à partir du site de la stimulation de la baie d&#39;IRM. En tant que tel, il serait intéressant de revisiter plusieurs des idées ci-dessus suggéré à l&#39;aide dans cette transition. Premièrement: l&#39;utilisation d&#39;une machine portative TMS mis en place dans un endroit aussi proche de la baie d&#39;IRM que possible. Deux: contourner tout mécanisme de mise en veille ...

<ul><li> Équipé pour l&#39;IRM IRMf (voir photo dans la vidéo est un Philips) </li><li> Dispositif TMS Capable de stimulation répétitive (en photo dans la vidéo est un Magstim) </li><li> Équipement stéréotaxie sans cadre (sur la photo de la vidéo est Brainsight) </li><li> Bouchons d&#39;oreilles </li><li> Président de réserve lors de la stimulation </li><li> Écran de projection arrière ou à l&#39;IRM Lunettes compatibles </li><li> Ecran blanc Stimuli </li></ul>

combining transcranial magnetic stimulation and fmri to examine the default mode network

Le réseau en mode par défaut est un groupe de régions du cerveau qui sont actives quand un individu n&#39;est pas axée sur le monde extérieur et le cerveau est au «repos éveillé.&quot; 1,2,3 On pense au réseau en mode par défaut correspond à l&#39;auto-référentielle ou «mise en œuvre interne» 2,3. Il a émis l&#39;hypothèse que, chez l&#39;homme, l&#39;activité au sein du réseau en mode par défaut est corrélée avec certaines pathologies (par exemple, l&#39;hyper-activation a été liée à la schizophrénie 4,5,6 et troubles du spectre autistique 7 alors que l&#39;hypo-activation du réseau a été liée à la maladie d&#39;Alzheimer et autres maladies neurodégénératives 8). En tant que tel, la modulation non invasif de ce réseau peut représenter une intervention thérapeutique potentielle pour un certain nombre de pathologies neurologiques et psychiatriques liés à l&#39;activation du réseau anormale. Un outil possible pour réaliser cette modulation est la stimulation magnétique transcrânienne: une neurostimulation non invasives et technique de neuromodulation qui peut transitoirement ou durablement moduler l&#39;excitabilité corticale (soit en augmentant ou en la diminuant) via l&#39;application d&#39;impulsions de champ magnétique localisé 9. Afin d&#39;explorer la propension du réseau en mode par défaut et la tolérance envers la modulation, nous allons combiner TMS (au lobe pariétal inférieur gauche) avec l&#39;imagerie par résonance magnétique fonctionnelle (IRMf). A travers cet article, nous allons examiner le protocole et les considérations nécessaires pour réussir à combiner ces deux outils neuroscientifiques.

Watch this Scientific Journal Video about Combining Transcranial Magnetic Stimulation and fMRI to Examine the Default Mode Network at JoVE.com

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

Dans cet article, nous examinons la méthodologie et les considérations pertinentes à la combinaison de TMS et de l&#39;IRMf pour étudier les effets de la stimulation cérébrale sur le réseau par défaut.

Alliant la stimulation magnétique transcrânienne et l&#39;IRMf pour examiner le réseau en mode par défaut

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

combining-transcranial-magnetic-stimulation-fmri-to-examine-default

Research

JoVE Journal

Neuroscience

12.8K vues.  Beth Israel Deaconess Medical Center. Dans cet article, nous examinons la méthodologie et les considérations pertinentes à la combinaison de TMS et de l'IRMf pour étudier les effets de la stimulation cérébrale sur le réseau par défaut.

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

A Novel Approach for Documenting Phosphenes Induced by Transcranial Magnetic Stimulation

Stimulation of the human visual cortex produces a transient perception of light, known as a phosphene. Phosphenes are induced by invasive electrical stimulation of the occipital cortex, but also by non-invasive Transcranial Magnetic Stimulation (TMS)1 of the same cortical regions. The intensity at which a phosphene is induced (phosphene threshold) is a well established measure of visual cortical excitability and is used to study cortico-cortical interactions, functional organization 2, susceptibility to pathology 3,4 and visual processing 5-7. Phosphenes are typically defined by three characteristics: they are observed in the visual hemifield contralateral to stimulation; they are induced when the subject s eyes are open or closed, and their spatial location changes with the direction of gaze 2. Various methods have been used to document phosphenes, but a standardized methodology is lacking. We demonstrate a reliable procedure to obtain phosphene threshold values and introduce a novel system for the documentation and analysis of phosphenes. We developed the Laser Tracking and Painting system (LTaP), a low cost, easily built and operated system that records the location and size of perceived phosphenes in real-time. The LTaP system provides a stable and customizable environment for quantification and analysis of phosphenes.

Phosphenes are transient percepts of light that can be induced by applying Transcranial Magnetic Stimulation (TMS) to visually sensitive regions of cortex. We demonstrate a standard protocol for determining the phosphene threshold value and introduce a novel method for quantifying and analyzing perceived phosphenes.

Une nouvelle approche pour la documentation phosphènes induite par la stimulation magnétique transcrânienne

Stimulation of the human visual cortex produces a transient perception of light, known as a phosphene. Phosphenes are induced by invasive electrical ...

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Neurosciences

Extracting Visual Evoked Potentials from EEG Data Recorded During fMRI-guided Transcranial Magnetic Stimulation

Transcranial Magnetic Stimulation (TMS) is an effective method for establishing a causal link between a cortical area and cognitive/neurophysiological effects. Specifically, by creating a transient interference with the normal activity of a target region and measuring changes in an electrophysiological signal, we can establish a causal link between the stimulated brain area or network and the electrophysiological signal that we record. If target brain areas are functionally defined with prior fMRI scan, TMS could be used to link the fMRI activations with evoked potentials recorded. However, conducting such experiments presents significant technical challenges given the high amplitude artifacts introduced into the EEG signal by the magnetic pulse, and the difficulty to successfully target areas that were functionally defined by fMRI. Here we describe a methodology for combining these three common tools: TMS, EEG, and fMRI. We explain how to guide the stimulator&#39;s coil to the desired target area using anatomical or functional MRI data, how to record EEG during concurrent TMS, how to design an ERP study suitable for EEG-TMS combination and how to extract reliable ERP from the recorded data. We will provide representative results from a previously published study, in which fMRI-guided TMS was used concurrently with EEG to show that the face-selective N1 and the body-selective N1 component of the ERP are associated with distinct neural networks in extrastriate cortex. This method allows us to combine the high spatial resolution of fMRI with the high temporal resolution of TMS and EEG and therefore obtain a comprehensive understanding of the neural basis of various cognitive processes.

This paper describes a method for collecting and analyzing electroencephalography (EEG) data during concurrent transcranial magnetic stimulation (TMS) guided by activations revealed with functional magnetic resonance imaging (fMRI). A method for TMS artifact removal and extraction of event related potentials is described as well as considerations in paradigm design and experimental setup.

Extraction Potentiels évoqués visuels de l&#39;EEG données enregistrées pendant l&#39;IRMf guidée stimulation magnétique transcrânienne

Transcranial Magnetic Stimulation (TMS) is an effective method for establishing a causal link between a cortical area and cognitive/neurophysiological ...

The Use of Magnetic Resonance Spectroscopy as a Tool for the Measurement of Bi-hemispheric Transcranial Electric Stimulation Effects on Primary Motor Cortex Metabolism

Transcranial direct current stimulation (tDCS) is a neuromodulation technique that has been increasingly used over the past decade in the treatment of neurological and psychiatric disorders such as stroke and depression. Yet, the mechanisms underlying its ability to modulate brain excitability to improve clinical symptoms remains poorly understood 33. To help improve this understanding, proton magnetic resonance spectroscopy (1H-MRS) can be used as it allows the in vivo quantification of brain metabolites such as &#947;-aminobutyric acid (GABA) and glutamate in a region-specific manner 41. In fact, a recent study demonstrated that 1H-MRS is indeed a powerful means to better understand the effects of tDCS on neurotransmitter concentration 34. This article aims to describe the complete protocol for combining tDCS (NeuroConn MR compatible stimulator) with 1H-MRS at 3 T using a MEGA-PRESS sequence. We will describe the impact of a protocol that has shown great promise for the treatment of motor dysfunctions after stroke, which consists of bilateral stimulation of primary motor cortices 27,30,31. Methodological factors to consider and possible modifications to the protocol are also discussed.

This article aims to describe a basic protocol for combining transcranial direct current stimulation (tDCS) with proton magnetic resonance spectroscopy (1H-MRS) measurements to investigate the effects of bilateral stimulation on primary motor cortex metabolism.

L&#39;utilisation de la spectroscopie par résonance magnétique, un outil pour la mesure de la Bi-hémisphériques transcrânienne électriques effets de stimulation sur le moteur primaire Cortex métabolisme

Transcranial direct current stimulation (tDCS) is a neuromodulation technique that has been increasingly used over the past decade in the treatment of ...

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

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

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

Effets de la Stimulation transcrânienne courant alternatif sur le Cortex moteur primaire par en ligne approche combinée avec la Stimulation magnétique transcrânienne

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

Combined Transcranial Magnetic Stimulation and Electroencephalography of the Dorsolateral Prefrontal Cortex

Transcranial magnetic stimulation (TMS) is a non-invasive method that produces neural excitation in the cortex by means of brief, time-varying magnetic field pulses. The initiation of cortical activation or its modulation depends on the background activation of the neurons of the cortical region activated, the characteristics of the coil, its position and its orientation with respect to the head. TMS combined with simultaneous electrocephalography (EEG) and neuronavigation (nTMS-EEG) allows for the assessment of cortico-cortical excitability and connectivity in almost all cortical areas in a reproducible manner. This advance makes nTMS-EEG a powerful tool that can accurately assess brain dynamics and neurophysiology in test-retest paradigms that are required for clinical trials. Limitations of this method include artifacts that cover the initial brain reactivity to stimulation. Thus, the process of removing artifacts may also extract valuable information. Moreover, the optimal parameters for dorsolateral prefrontal (DLPFC) stimulation are not fully known and current protocols utilize variations from the motor cortex (M1) stimulation paradigms. However, evolving nTMS-EEG designs hope to address these issues. The protocol presented here introduces some standard practices for assessing neurophysiological functioning from stimulation to the DLPFC that can be applied in patients with treatment resistant psychiatric disorders that receive treatment such as transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), magnetic seizure therapy (MST) or electroconvulsive therapy (ECT).

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.

La Stimulation magnétique transcrânienne combinée et électroencéphalographie du Cortex préfrontal dorsolatéral

Transcranial magnetic stimulation (TMS) is a non-invasive method that produces neural excitation in the cortex by means of brief, time-varying magnetic ...

Bilateral Assessment of the Corticospinal Pathways of the Ankle Muscles Using Navigated Transcranial Magnetic Stimulation

Distal leg muscles receive neural input from motor cortical areas via the corticospinal tract, which is one of the main motor descending pathway in humans and can be assessed using transcranial magnetic stimulation (TMS). Given the role of distal leg muscles in upright postural and dynamic tasks, such as walking, a growing research interest in the assessment and modulation of the corticospinal tracts relative to the function of these muscles has emerged in the last decade. However, methodological parameters used in previous work have varied across studies making the interpretation of results from cross-sectional and longitudinal studies less robust. Therefore, use of a standardized TMS protocol specific to the assessment of leg muscles&#39; corticomotor response (CMR) will allow for direct comparison of results across studies and cohorts. The objective of this paper is to present a protocol that provides the flexibility to simultaneously assess the bilateral CMR of two main ankle antagonistic muscles, the tibialis anterior and soleus, using single pulse TMS with a neuronavigation system. The present protocol is applicable while the examined muscle is either fully relaxed or isometrically contracted at a defined percentage of maximum isometric voluntary contraction. Using each subject&#39;s structural MRI with the neuronavigation system ensures accurate and precise positioning of the coil over the leg cortical representations during assessment. Given the inconsistency in CMR derived measures, this protocol also describes a standardized calculation of these measures using automated algorithms. Though this protocol is not conducted during upright postural or dynamic tasks, it&#160;can be used to assess bilaterally any pair of leg muscles, either antagonistic or synergistic, in both neurologically intact and impaired subjects.

The present protocol describes the simultaneous, bilateral assessment of the corticomotor response of the tibialis anterior and soleus during rest and tonic voluntary activation using a single pulse transcranial magnetic stimulation and neuronavigation system.

Évaluation bilatérale des voies Corticospinaux les muscles de la cheville à l’aide de navigué la Stimulation magnétique transcrânienne

Distal leg muscles receive neural input from motor cortical areas via the corticospinal tract, which is one of the main motor descending pathway in humans ...

Measuring and Manipulating Functionally Specific Neural Pathways in the Human Motor System with Transcranial Magnetic Stimulation

Understanding interactions between brain areas is important for the study of goal-directed behavior. Functional neuroimaging of brain connectivity has provided important insights into fundamental processes of the brain like cognition, learning, and motor control. However, this approach cannot provide causal evidence for the involvement of brain areas of interest. Transcranial magnetic stimulation (TMS) is a powerful, noninvasive tool for studying the human brain that can overcome this limitation by transiently modifying brain activity. Here, we highlight recent advances using a paired-pulse, dual-site TMS method with two coils that causally probes cortico-cortical interactions in the human motor system during different task contexts. Additionally, we describe a dual-site TMS protocol based on cortical paired associative stimulation (cPAS) that transiently enhances synaptic efficiency in two interconnected brain areas by applying repeated pairs of cortical stimuli with two coils. These methods can provide a better understanding of the mechanisms underlying cognitive-motor function as well as a new perspective on manipulating specific neural pathways in a targeted fashion to modulate brain circuits and improve behavior. This approach may prove to be an effective tool to develop more sophisticated models of brain-behavior relations and improve diagnosis and treatment of many neurological and psychiatric disorders.

This article describes new approaches to measure and strengthen functionally specific neural pathways with transcranial magnetic stimulation. These advanced noninvasive brain stimulation methodologies can provide new opportunities for the understanding of brain-behavior relations and development of new therapies to treat brain disorders.

Mesurer et manipuler des voies neuronales fonctionnellement spécifiques dans le système moteur humain avec stimulation magnétique transcrânienne

Understanding interactions between brain areas is important for the study of goal-directed behavior. Functional neuroimaging of brain connectivity has ...

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

Neuroimaging is typically perceived as a resource demanding discipline. While this is the case in certain circumstances, institutions with limited resources have historically contributed significantly to the field of neuroscience, including neuroimaging. In the study of self-deception, we have successfully employed single-pulse TMS to determine the brain correlates of abilities including overclaiming and self-enhancement. Even without the use of neuro-navigation, methods provided here lead to successful outcomes. For example, it was discovered that decreases in self-deceptive responding lead to a decrease in affect. These methods provide data that are reliable and valid, and such methods provide research opportunities otherwise unavailable.&#160;Through the use of these methods, the overall knowledge base in the field of neuroscience is expanded, providing research opportunities to students such as those at our institution&#160;(Montclair State University is a Hispanic-Serving Institute) who are often denied such research experiences.

Transcranial Magnetic Stimulation (TMS) and low-frequency TMS (lfTMS) have&#160;been demonstrated to be major contributors to brain literature. Here we highlight the methods for investigating the cortical correlates of self-deception using TMS.

Utiliser la stimulation magnétique transcrânienne dans un environnement aux ressources limitées pour établir des relations cerveau-comportement

Neuroimaging is typically perceived as a resource demanding discipline. While this is the case in certain circumstances, institutions with limited ...

Conventional and Threshold-Tracking Transcranial Magnetic Stimulation Tests for Single-handed Operation

Most single-pulse transcranial magnetic stimulation (TMS) parameters (e.g., motor threshold, stimulus-response function, cortical silent period) are used to examine corticospinal excitability. Paired-pulse TMS paradigms (e.g., short- and long-interval intracortical inhibition (SICI/LICI), short-interval intracortical facilitation (SICF), and short- and long-latency afferent inhibition (SAI/LAI)) provide information about intracortical inhibitory and facilitatory networks. This has long been done by the conventional TMS method of measuring changes in the size of the motor-evoked potentials (MEPs) in response to stimuli of constant intensity. An alternative threshold-tracking approach has recently been introduced whereby the stimulus intensity for a target amplitude is tracked. The diagnostic utility of threshold-tracking SICI in amyotrophic lateral sclerosis (ALS) has been shown in previous studies. However, threshold-tracking TMS has only been used in a few centers, in part due to the lack of readily available software but also perhaps due to uncertainty over its relationship to conventional single- and paired-pulse TMS measurements.
A menu-driven suite of semi-automatic programs has been developed to facilitate the broader use of threshold-tracking TMS techniques and to enable direct comparisons with conventional amplitude measurements. These have been designed to control three types of magnetic stimulators and allow recording by a single operator of the common single- and paired-pulse TMS protocols.
This paper shows how to record a number of single- and paired-pulse TMS protocols on healthy subjects and analyze the recordings. These TMS protocols are fast and easy to perform and can provide useful biomarkers in different neurological disorders, particularly neurodegenerative diseases such as ALS.

We present a suite of standardized single- and paired-pulse transcranial magnetic stimulation (TMS) recording protocols, with options for conventional amplitude measurements and threshold-tracking. This program can control three different types of magnetic stimulators and is designed to enable all tests to be performed conveniently by a single operator.

Tests de stimulation magnétique transcrânienne conventionnels et à suivi de seuil pour un fonctionnement à une seule main

Most single-pulse transcranial magnetic stimulation (TMS) parameters (e.g., motor threshold, stimulus-response function, cortical silent period) are used ...

Stimulation combinée des nerfs périphériques et paramètre de pouls contrôlable TMS

Combined Peripheral Nerve Stimulation and Controllable Pulse Parameter Transcranial Magnetic Stimulation to Probe Sensorimotor Control and Learning

Skilled motor ability depends on efficiently integrating sensory afference into the appropriate motor commands. Afferent inhibition provides a valuable tool to probe the procedural and declarative influence over sensorimotor integration during skilled motor actions. This manuscript describes the methodology and contributions of short-latency afferent inhibition (SAI) for understanding sensorimotor integration. SAI quantifies the effect of a convergent afferent volley on the corticospinal motor output evoked by transcranial magnetic stimulation (TMS). The afferent volley is triggered by the electrical stimulation of a peripheral nerve. The TMS stimulus is delivered to a location over the primary motor cortex that elicits a reliable motor-evoked response in a muscle served by that afferent nerve. The extent of inhibition in the motor-evoked response reflects the magnitude of the afferent volley converging on the motor cortex and involves central GABAergic and cholinergic contributions. The cholinergic involvement in SAI makes SAI a possible marker of declarative-procedural interactions in sensorimotor performance and learning. More recently, studies have begun manipulating the TMS current direction in SAI to tease apart the functional significance of distinct sensorimotor circuits in the primary motor cortex for skilled motor actions. The ability to control additional pulse parameters (e.g., the pulse width) with state-of-the-art controllable pulse parameter TMS (cTMS) has enhanced the selectivity of the sensorimotor circuits probed by the TMS stimulus and provided an opportunity to create more refined models of sensorimotor control and learning. Therefore, the current manuscript focuses on SAI assessment using cTMS. However, the principles outlined here also apply to SAI assessed using conventional fixed pulse width TMS stimulators and other forms of afferent inhibition, such as long-latency afferent inhibition (LAI).

Pleins feux sur l’auteur : Stimulation combinée des nerfs périphériques et paramètre d’impulsion contrôlable Stimulation magnétique transcrânienne pour sonder le contrôle sensorimoteur et l’apprentiss

Short-latency afferent inhibition (SAI) is a transcranial magnetic stimulation protocol to probe sensorimotor integration. This article describes how SAI can be used to study the convergent sensorimotor loops in the motor cortex during sensorimotor behavior.

Stimulation combinée des nerfs périphériques et paramètre d’impulsion contrôlable Stimulation magnétique transcrânienne pour sonder le contrôle sensorimoteur et l’apprentissage

Skilled motor ability depends on efficiently integrating sensory afference into the appropriate motor commands. Afferent inhibition provides a valuable ...