Transcranial magnetic stimulation: studying motor neurophysiology of psychiatric disorders

Maeda, Fumiko; Pascual‐Leone, Álvaro

doi:10.1007/s00213-002-1216-x

Cited by 67 publications

(45 citation statements)

References 163 publications

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“…Resting MT is influenced by the orientation, density, and electrical susceptibility of the cortical neurons. As such, alterations in resting MT can reflect changes at a variety of levels [i.e., the neural membrane, axonal electronic properties, the structure and number of excitatory projections onto the primary motor cortex, or upregulation of receptors in this region 24 and hence represents a global assessment of the membrane excitability of pyramidal neurons 24,25 . With regards to active MT, voluntary contraction results in a reduction in motor threshold compared with resting conditions, which is thought to be indicative of the magnitude of voluntary motor drive to the corticomuscular pathway 26 .…”

Section: Physiology Of Single Pulse Tms Outcomementioning

confidence: 99%

Utilizing Transcranial Magnetic Stimulation to Study the Human Neuromuscular System

Goss

Hoffman

Clark

2012

JoVE

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Transcranial magnetic stimulation (TMS) has been in use for more than 20 years 1 , and has grown exponentially in popularity over the past decade. While the use of TMS has expanded to the study of many systems and processes during this time, the original application and perhaps one of the most common uses of TMS involves studying the physiology, plasticity and function of the human neuromuscular system. Single pulse TMS applied to the motor cortex excites pyramidal neurons transsynaptically 2 ( Figure 1) and results in a measurable electromyographic response that can be used to study and evaluate the integrity and excitability of the corticospinal tract in humans 3 . Additionally, recent advances in magnetic stimulation now allows for partitioning of cortical versus spinal excitability 4,5 . For example, paired-pulse TMS can be used to assess intracortical facilitatory and inhibitory properties by combining a conditioning stimulus and a test stimulus at different interstimulus intervals 3,4,[6][7][8] . In this video article we will demonstrate the methodological and technical aspects of these techniques. Specifically, we will demonstrate singlepulse and paired-pulse TMS techniques as applied to the flexor carpi radialis (FCR) muscle as well as the erector spinae (ES) musculature. Our laboratory studies the FCR muscle as it is of interest to our research on the effects of wrist-hand cast immobilization on reduced muscle performance 6,9 , and we study the ES muscles due to these muscles clinical relevance as it relates to low back pain 8 . With this stated, we should note that TMS has been used to study many muscles of the hand, arm and legs, and should iterate that our demonstrations in the FCR and ES muscle groups are only selected examples of TMS being used to study the human neuromuscular system. Video LinkThe video component of this article can be found at http://www.jove.com/video/3387/ Protocol 1. Single and Paired-Pulse TMS of the FCR and ES Muscles 1. Basic Safety Precautions: Prior to performing TMS on a human subject it is necessary to first screen them for basic safety precautions as it pertains to exposure to a magnetic field. In our laboratory we follow the screening guidelines set forth by the Institute for Magnetic Resonance Safety, Education and Research 10 . In our laboratory we also routinely exclude individuals with a family history of epilepsy seizures. We also require subjects undergoing TMS of the ES muscles to wear earplugs and a mouth guard due to the less focal and stronger stimulation intensities. Electrical Recordings:To examine TMS responses in the motor system it is necessary to record electromyographic (EMG) signals from skeletal muscles. For the FCR muscle we place surface electrodes on the forearm using a bipolar electrode arrangement located longitudinally over the muscle on shaved and abraded skin as we have previously described 7,11 . For the erector spinae muscles we use a similar electrode arrangement located longitudinally over the muscles at the L3-L5 vertebral level...

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Section: Physiology Of Single Pulse Tms Outcomementioning

confidence: 99%

Utilizing Transcranial Magnetic Stimulation to Study the Human Neuromuscular System

Goss

Hoffman

Clark

2012

JoVE

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“…Die seit 1985 eingeführ-te transkranielle magnetische Stimulation (TMS) [3] stellt eine nichtinvasive, nebenwirkungsarme und im Gegensatz zur transkraniellen elektrischen Stimulation (TES) schmerzlose Methode zur Stimulation umschriebener Kortexareale dar. Da eine quantifizierbare Messung der kortikalen Erregung mit der TMS direkt nur im motorischen System möglich ist und bei Stimulation über dem motorischen Areal der Hirnrinde ein gut reproduzierbares, durch Oberflächen-EMG-Elektroden über dem entsprechenden Zielmuskel erhältliches Muskelantwortpotenzial (MEP) leicht abzuleiten ist, lag der Schwerpunkt der Untersuchungen zunächst auf der Erregungsleitung motorischer kortikospinaler Bahnen [29]. Messungen der Erregbarkeit anderer Systeme wie beispielsweise des visuellen Systems anhand der Angaben des Probanden (Induktion von Phosphenen) sind jedoch ebenfalls möglich.…”

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“…Bei schizophrenen Patienten sind neben Beeinträchtigungen anderer neuronaler Netzwerke Dysfunktionen des motorischen Systems ein bekanntes Phäno-men [29]. Neben den extrapyramidal-motorischen Störungen (EPS) bei noch nicht mit Neuroleptika behandelten (unmedizierten) Patienten zählen hierzu insbesondere eine generelle Störung der Feinmotorik, der manuellen Geschicklichkeit, der bimanuellen Koordination, Defizite bei der Untersuchung so genannter antisakkadischer Augenbewegungen und der psychomotorischen Schnelligkeit [10].…”

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“…Durch die Verwendung unterschiedlicher Untersuchungsdesigns und TMS-Techniken kön-nen gezielt verschiedene Aspekte der kortikalen Exzitabilität untersucht werden. [29]. Dieser Stromfluss wird senkrecht zur Ausrichtung des Magnetfelds und damit parallel zur Spulenebene induziert.…”

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“…Neuronen der Pyramidenbahn liegen fast senkrecht zum Kortex, und somit werden nur wenige durch das Magnetfeld stimuliert. Die Exzitation der Pyramidenbahnzellen findet indirekt durch Stimulation der zum Kortex horizontal liegenden exzitatorischen Interneuronen statt [29]. Diese so entstandenen Wellen werden auch I-Wellen genannt ("I-wave") und weisen eine Latenz von etwa 2 ms auf.…”

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Cortical excitability in schizophrenia

2007

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Abnormalities in brain plasticity, including abnormal information processing by disturbed cortical inhibition and facilitation in schizophrenia, have been described several times in the past. Transcranial magnetic stimulation (TMS) provides a neurophysiological technique for the measurement of cortical excitability, especially of the motoneural system. With TMS it is possible to explore important aspects of the pathophysiological mechanisms underlying schizophrenia using recently developed paradigms (paired pulse method, cortical silent period). This review summarizes the results of available diagnostic TMS studies in schizophrenia. Studies investigating the efficacy of therapeutic repetitive magnetic stimulation in patients with treatment resistant hallucinations or predominantly negative symptoms were not considered. The reviewed studies support the assumption of reduced cortical inhibition, probably caused by GABAergic deficit, in schizophrenia. Factors influencing the study results, the limitations of this promising technique in schizophrenia, and further research options are discussed.

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Farah

Smith

Ilieva

et al. 2013

WIRES Cognitive Science

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Cognitive enhancement refers to the improvement of cognitive ability in normal healthy individuals. In this article, we focus on the use of pharmaceutical agents and brain stimulation for cognitive enhancement, reviewing the most common methods of pharmacologic and electronic cognitive enhancement, and the mechanisms by which they are believed to work, the effectiveness of these methods and their prevalence. We note the many gaps in our knowledge of these matters, including open questions about the size, reliability and nature of the enhancing effects, and we conclude with recommendations for further research. WIREs Cogn Sci 2014, 5:95-103. doi: 10.1002/wcs.1250 CONFLICT OF INTEREST: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website.

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Transcranial magnetic stimulation: studying motor neurophysiology of psychiatric disorders

Abstract: Future studies using TMS alone or in combination with other neuroimaging techniques promise to further expand the application of TMS from studies of motor excitability to higher cognitive functions.

Cited by 67 publications

References 163 publications

Utilizing Transcranial Magnetic Stimulation to Study the Human Neuromuscular System

Utilizing Transcranial Magnetic Stimulation to Study the Human Neuromuscular System

Cortical excitability in schizophrenia

Cognitive enhancement

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