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Lee HJ, Woudsma KJ, Ishraq MF, Lin FH. Design of coil holder for the improved maneuvering in concurrent TMS-MRI. Brain Stimul 2023; 16:966-968. [PMID: 37271336 DOI: 10.1016/j.brs.2023.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 05/31/2023] [Accepted: 06/01/2023] [Indexed: 06/06/2023] Open
Abstract
BACKGROUND Concurrent transcranial magnetic stimulation (TMS) and magnetic resonance imaging (MRI) is time-consuming because of the limited space in the MRI bore and the sophisticated placement and orientation of the TMS coil to elicit the desired brain activities and behaviors. OBJECTIVE We developed a TMS coil holder capable of quick adjustment of the TMS coil position and orientation. The holder can also hold an MRI receiver coil array. METHODS A holder with one controlling knob, two omni-direction rotation joints, and two in-plane rotation joints was developed. RESULTS Different TMS coil positions and orientations can be arranged and fixed in seconds. The holder can also accommodate two TMS coils to allow for multi-coil TMS-MRI. CONCLUSION Our development significantly improves the workflow of the concurrent TMS-MRI in new neuroscience studies and clinical applications.
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Affiliation(s)
- Hsin-Ju Lee
- Sunnybrook Research Institute, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Ontario, Canada
| | - K J Woudsma
- Sunnybrook Research Institute, Toronto, Ontario, Canada
| | | | - Fa-Hsuan Lin
- Sunnybrook Research Institute, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Ontario, Canada.
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Mizutani-Tiebel Y, Tik M, Chang KY, Padberg F, Soldini A, Wilkinson Z, Voon CC, Bulubas L, Windischberger C, Keeser D. Concurrent TMS-fMRI: Technical Challenges, Developments, and Overview of Previous Studies. Front Psychiatry 2022; 13:825205. [PMID: 35530029 PMCID: PMC9069063 DOI: 10.3389/fpsyt.2022.825205] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 03/09/2022] [Indexed: 11/13/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) is a promising treatment modality for psychiatric and neurological disorders. Repetitive TMS (rTMS) is widely used for the treatment of psychiatric and neurological diseases, such as depression, motor stroke, and neuropathic pain. However, the underlying mechanisms of rTMS-mediated neuronal modulation are not fully understood. In this respect, concurrent or simultaneous TMS-fMRI, in which TMS is applied during functional magnetic resonance imaging (fMRI), is a viable tool to gain insights, as it enables an investigation of the immediate effects of TMS. Concurrent application of TMS during neuroimaging usually causes severe artifacts due to magnetic field inhomogeneities induced by TMS. However, by carefully interleaving the TMS pulses with MR signal acquisition in the way that these are far enough apart, we can avoid any image distortions. While the very first feasibility studies date back to the 1990s, recent developments in coil hardware and acquisition techniques have boosted the number of TMS-fMRI applications. As such, a concurrent application requires expertise in both TMS and MRI mechanisms and sequencing, and the hurdle of initial technical set up and maintenance remains high. This review gives a comprehensive overview of concurrent TMS-fMRI techniques by collecting (1) basic information, (2) technical challenges and developments, (3) an overview of findings reported so far using concurrent TMS-fMRI, and (4) current limitations and our suggestions for improvement. By sharing this review, we hope to attract the interest of researchers from various backgrounds and create an educational knowledge base.
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Affiliation(s)
- Yuki Mizutani-Tiebel
- Department of Psychiatry and Psychotherapy, University Hospital LMU, Munich, Germany.,Neuroimaging Core Unit Munich - NICUM, University Hospital LMU, Munich, Germany
| | - Martin Tik
- High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Kai-Yen Chang
- Department of Psychiatry and Psychotherapy, University Hospital LMU, Munich, Germany.,Neuroimaging Core Unit Munich - NICUM, University Hospital LMU, Munich, Germany
| | - Frank Padberg
- Department of Psychiatry and Psychotherapy, University Hospital LMU, Munich, Germany.,Neuroimaging Core Unit Munich - NICUM, University Hospital LMU, Munich, Germany
| | - Aldo Soldini
- Department of Psychiatry and Psychotherapy, University Hospital LMU, Munich, Germany.,Neuroimaging Core Unit Munich - NICUM, University Hospital LMU, Munich, Germany.,International Max Planck Research School for Translational Psychiatry, Munich, Germany
| | - Zane Wilkinson
- Department of Psychiatry and Psychotherapy, University Hospital LMU, Munich, Germany.,Neuroimaging Core Unit Munich - NICUM, University Hospital LMU, Munich, Germany
| | - Cui Ci Voon
- Department of Psychiatry and Psychotherapy, University Hospital LMU, Munich, Germany.,Neuroimaging Core Unit Munich - NICUM, University Hospital LMU, Munich, Germany
| | - Lucia Bulubas
- Department of Psychiatry and Psychotherapy, University Hospital LMU, Munich, Germany.,Neuroimaging Core Unit Munich - NICUM, University Hospital LMU, Munich, Germany.,International Max Planck Research School for Translational Psychiatry, Munich, Germany
| | - Christian Windischberger
- High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Daniel Keeser
- Department of Psychiatry and Psychotherapy, University Hospital LMU, Munich, Germany.,Neuroimaging Core Unit Munich - NICUM, University Hospital LMU, Munich, Germany.,Department of Radiology, University Hospital LMU, Munich, Germany
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3
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Bergmann TO, Varatheeswaran R, Hanlon CA, Madsen KH, Thielscher A, Siebner HR. Concurrent TMS-fMRI for causal network perturbation and proof of target engagement. Neuroimage 2021; 237:118093. [PMID: 33940146 DOI: 10.1016/j.neuroimage.2021.118093] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/06/2021] [Accepted: 04/14/2021] [Indexed: 12/12/2022] Open
Abstract
The experimental manipulation of neural activity by neurostimulation techniques overcomes the inherent limitations of correlative recordings, enabling the researcher to investigate causal brain-behavior relationships. But only when stimulation and recordings are combined, the direct impact of the stimulation on neural activity can be evaluated. In humans, this can be achieved non-invasively through the concurrent combination of transcranial magnetic stimulation (TMS) with functional magnetic resonance imaging (fMRI). Concurrent TMS-fMRI allows the assessment of the neurovascular responses evoked by TMS with excellent spatial resolution and full-brain coverage. This enables the functional mapping of both local and remote network effects of TMS in cortical as well as deep subcortical structures, offering unique opportunities for basic research and clinical applications. The purpose of this review is to introduce the reader to this powerful tool. We will introduce the technical challenges and state-of-the art solutions and provide a comprehensive overview of the existing literature and the available experimental approaches. We will highlight the unique insights that can be gained from concurrent TMS-fMRI, including the state-dependent assessment of neural responsiveness and inter-regional effective connectivity, the demonstration of functional target engagement, and the systematic evaluation of stimulation parameters. We will also discuss how concurrent TMS-fMRI during a behavioral task can help to link behavioral TMS effects to changes in neural network activity and to identify peripheral co-stimulation confounds. Finally, we will review the use of concurrent TMS-fMRI for developing TMS treatments of psychiatric and neurological disorders and suggest future improvements for further advancing the application of concurrent TMS-fMRI.
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Affiliation(s)
- Til Ole Bergmann
- Neuroimaging Center (NIC), Focus Program Translational Neuroscience (FTN), Johannes Gutenberg University Medical Center, Langenbeckstr. 1, 55131, Mainz, Germany; Leibniz Institute for Resilience Research, Wallstraße 7-9, 55122, Mainz, Germany.
| | - Rathiga Varatheeswaran
- Neuroimaging Center (NIC), Focus Program Translational Neuroscience (FTN), Johannes Gutenberg University Medical Center, Langenbeckstr. 1, 55131, Mainz, Germany; Leibniz Institute for Resilience Research, Wallstraße 7-9, 55122, Mainz, Germany
| | - Colleen A Hanlon
- Department of Cancer Biology, Wake Forest School of Medicine, 1 Medical Center Blvd., Winston-Salem, NC 27157, USA
| | - Kristoffer H Madsen
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Kettegård Allé 30, 2650, Hvidovre, Denmark; Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Axel Thielscher
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Kettegård Allé 30, 2650, Hvidovre, Denmark; Department of Electrical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Hartwig Roman Siebner
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Kettegård Allé 30, 2650, Hvidovre, Denmark; Department of Neurology, Copenhagen University Hospital Bispebjerg, Bispebjerg Bakke 23, 2400 København NV, Denmark; Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
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4
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Goetz SM, Kozyrkov IC, Luber B, Lisanby SH, Murphy DLK, Grill WM, Peterchev AV. Accuracy of robotic coil positioning during transcranial magnetic stimulation. J Neural Eng 2019; 16:054003. [PMID: 31189147 DOI: 10.1088/1741-2552/ab2953] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Robotic positioning systems for transcranial magnetic stimulation (TMS) promise improved accuracy and stability of coil placement, but there is limited data on their performance. Investigate the usability, accuracy, and limitations of robotic coil placement with a commercial system, ANT Neuro, in a TMS study. APPROACH 21 subjects underwent a total of 79 TMS sessions corresponding to 160 hours under robotic coil control. Coil position and orientation were monitored concurrently through an additional neuronavigation system. MAIN RESULTS Robot setup took on average 14.5 min. The robot achieved low position and orientation error with median 3.54 mm (overall, 1.34 mm without coil-head spacing) and 3.48°. The error increased over time at a rate of 0.4%/minute for both position and orientation. SIGNIFICANCE Robotic TMS systems can provide accurate and stable coil position and orientation in long TMS sessions. Lack of pressure feedback and of manual adjustment of all coil degrees of freedom were limitations of this robotic system.
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Affiliation(s)
- Stefan M Goetz
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC 27710, United States of America. Department of Neurosurgery, Duke University, Durham, NC 27710, United States of America. Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708, United States of America
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5
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Dowdle LT, Brown TR, George MS, Hanlon CA. Single pulse TMS to the DLPFC, compared to a matched sham control, induces a direct, causal increase in caudate, cingulate, and thalamic BOLD signal. Brain Stimul 2018. [PMID: 29530447 DOI: 10.1016/j.brs.2018.02.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND In the 20 years since our group established the feasibility of performing interleaved TMS/fMRI, no studies have reported direct comparisons of active prefrontal stimulation with a matched sham. Thus, for all studies there is concern about what is truly the TMS effect on cortical neurons. OBJECTIVE After developing a sham control for use within the MRI scanner, we used fMRI to test the hypothesis of greater regional BOLD responses for active versus control stimulation. METHODS We delivered 4 runs of interleaved TMS/fMRI with a limited field of view (16 slices, centered at AC-PC) to the left DLPFC (2 active, 2 control; counterbalanced) of 20 healthy individuals (F3; 20 pulses/run, interpulse interval:10-15sec, TR:1sec). In the control condition, 3 cm of foam was placed between the TMS coil and the scalp. This ensured magnetic field decay, but preserved the sensory aspects of each pulse (empirically evaluated in a subset of 10 individuals). RESULTS BOLD increases in the cingulate, thalamus, insulae, and middle frontal gyri (p < 0.05, FWE corrected) were found during both active and control stimulation. However, relative to control, active stimulation caused elevated BOLD signal in the anterior cingulate, caudate and thalamus. No significant difference was found in auditory regions. CONCLUSION(S) This TMS/fMRI study evaluated a control condition that preserved many of the sensory features of TMS while reducing magnetic field entry. These findings support a relationship between single pulses of TMS and activity in anatomically connected regions, but also underscore the importance of using a sham condition in future TMS/fMRI studies.
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Affiliation(s)
- Logan T Dowdle
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States; Department of Neurosciences, Medical University of South Carolina, Charleston, SC, United States
| | - Truman R Brown
- Department of Radiology, Medical University of South Carolina, Charleston, SC, United States; Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, United States
| | - Mark S George
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States; Department of Neurosciences, Medical University of South Carolina, Charleston, SC, United States; Department of Radiology, Medical University of South Carolina, Charleston, SC, United States; Ralph H Johnson Veterans Administration Medical Center, Charleston, SC, United States
| | - Colleen A Hanlon
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States; Department of Neurosciences, Medical University of South Carolina, Charleston, SC, United States; Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, United States; Ralph H Johnson Veterans Administration Medical Center, Charleston, SC, United States.
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6
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Wang WT, Xu B, Butman JA. Improved SNR for combined TMS-fMRI: A support device for commercially available body array coil. J Neurosci Methods 2017; 289:1-7. [PMID: 28673806 DOI: 10.1016/j.jneumeth.2017.06.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 06/27/2017] [Accepted: 06/29/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation tool extensively used in clinical and cognitive neuroscience research. TMS has been applied during functional magnetic resonance imaging (i.e., concurrent/interleaved TMS-fMRI) to understand neural mechanisms underlying cognitive functions. However, no advanced commercial multi-channel whole-brain array MR coils can fit the large TMS coil. We developed a low-cost and easy-to-configure setup that takes advantage of the superior signal-to-noise ratio (SNR) performance of commercially available flexible body array coils that can accommodate the TMS coil. NEW METHOD Two flexible MRI body array coils (i.e., the Combo coil) were fitted on a simple coil support with a TMS-coil holder. Phantom and in vivo images acquired using the Combo coil with and without a TMS coil were compared with those from a product 12-channel (12CH) form-fit head array coil. RESULTS Relative to the 12CH head coil, images acquired using the Combo coil were of similar quality, but with increased noise levels, leading to moderately reduced temporal SNR values. COMPARISON WITH EXISTING METHOD A previous study reported that the temporal SNR of a product 12CH head coil was twice that of a transmit/receive volume birdcage coil commonly used in combined TMS-fMRI. Together with the results of the present work, they indicate that the Combo-coil setup improves SNR performance for combined TMS-fMRI acquisition. CONCLUSION The inexpensive and easy-to-configure Combo-coil setup offers an effective and likely superior alternative to transmit/receive birdcage coil for combined TMS-fMRI.
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Affiliation(s)
- Wen-Tung Wang
- Center for Neuroscience and Regenerative Medicine, Bethesda, MD, USA.
| | - Benjamin Xu
- Center for Neuroscience and Regenerative Medicine, Bethesda, MD, USA; National Institute of Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - John A Butman
- Center for Neuroscience and Regenerative Medicine, Bethesda, MD, USA; Radiology and Imaging Science, Clinical Center, NIH, Bethesda, MD, USA
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7
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Mobilization of Medial and Lateral Frontal-Striatal Circuits in Cocaine Users and Controls: An Interleaved TMS/BOLD Functional Connectivity Study. Neuropsychopharmacology 2016; 41:3032-3041. [PMID: 27374278 PMCID: PMC5101551 DOI: 10.1038/npp.2016.114] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 05/17/2016] [Accepted: 05/18/2016] [Indexed: 01/05/2023]
Abstract
The integrity of frontal-striatal circuits is an area of great interest in substance dependence literature, particularly as the field begins to develop neural circuit-specific brain stimulation treatments for these individuals. Prior research indicates that frontal-striatal connectivity is disrupted in chronic cocaine users in a baseline (resting) state. It is unclear, however, if this is also true when these circuits are mobilized by an external source. In this study, we measured the functional and structural integrity of frontal-striatal circuitry involved in limbic arousal and executive control in 36 individuals-18 cocaine-dependent individuals with a history of failed quit attempts and 18 age-matched controls. This was achieved by applying a transcranial magnetic stimulation to the medial prefrontal cortex (Brodmann area 10) and the dorsolateral prefrontal cortex (lateral Brodmann 9) while participants rested in the MRI scanner (TMS/BOLD imaging). Relative to the controls, cocaine users had a lower ventral striatal BOLD response to MPFC stimulation. The dorsal striatal BOLD response to DLPFC stimulation however was not significantly different between the groups. Among controls, DLPFC stimulation led to a reciprocal attenuation of MPFC activity (BA 10), but this pattern did not exist in cocaine users. No relationship was found between regional diffusion metrics and functional activity. Considered together these data suggest that, when engaged, cocaine users can mobilize their executive control system similar to controls, but that the 'set point' for mobilizing their limbic arousal system has been elevated-an interpretation consistent with opponent process theories of addiction.
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8
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Mandija S, Petrov PI, Neggers SFW, Luijten PR, van den Berg CAT. MR-based measurements and simulations of the magnetic field created by a realistic transcranial magnetic stimulation (TMS) coil and stimulator. NMR IN BIOMEDICINE 2016; 29:1590-1600. [PMID: 27669678 DOI: 10.1002/nbm.3618] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 07/04/2016] [Accepted: 08/12/2016] [Indexed: 06/06/2023]
Abstract
Transcranial magnetic stimulation (TMS) is an emerging technique that allows non-invasive neurostimulation. However, the correct validation of electromagnetic models of typical TMS coils and the correct assessment of the incident TMS field (BTMS ) produced by standard TMS stimulators are still lacking. Such a validation can be performed by mapping BTMS produced by a realistic TMS setup. In this study, we show that MRI can provide precise quantification of the magnetic field produced by a realistic TMS coil and a clinically used TMS stimulator in the region in which neurostimulation occurs. Measurements of the phase accumulation created by TMS pulses applied during a tailored MR sequence were performed in a phantom. Dedicated hardware was developed to synchronize a typical, clinically used, TMS setup with a 3-T MR scanner. For comparison purposes, electromagnetic simulations of BTMS were performed. MR-based measurements allow the mapping and quantification of BTMS starting 2.5 cm from the TMS coil. For closer regions, the intra-voxel dephasing induced by BTMS prohibits TMS field measurements. For 1% TMS output, the maximum measured value was ~0.1 mT. Simulations reflect quantitatively the experimental data. These measurements can be used to validate electromagnetic models of TMS coils, to guide TMS coil positioning, and for dosimetry and quality assessment of concurrent TMS-MRI studies without the need for crude methods, such as motor threshold, for stimulation dose determination.
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Affiliation(s)
- Stefano Mandija
- Center for Image Sciences, University Medical Center Utrecht, Utrecht, the Netherlands.
| | - Petar I Petrov
- Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Sebastian F W Neggers
- Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Peter R Luijten
- Center for Image Sciences, University Medical Center Utrecht, Utrecht, the Netherlands
- Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Cornelis A T van den Berg
- Center for Image Sciences, University Medical Center Utrecht, Utrecht, the Netherlands
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, the Netherlands
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9
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Peterchev AV, Deng ZD, Goetz SM. Advances in Transcranial Magnetic Stimulation Technology. Brain Stimul 2015. [DOI: 10.1002/9781118568323.ch10] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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10
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Navarro de Lara LI, Windischberger C, Kuehne A, Woletz M, Sieg J, Bestmann S, Weiskopf N, Strasser B, Moser E, Laistler E. A novel coil array for combined TMS/fMRI experiments at 3 T. Magn Reson Med 2014; 74:1492-501. [PMID: 25421603 PMCID: PMC4737243 DOI: 10.1002/mrm.25535] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 10/28/2014] [Accepted: 10/30/2014] [Indexed: 11/22/2022]
Abstract
Purpose To overcome current limitations in combined transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) studies by employing a dedicated coil array design for 3 Tesla. Methods The state‐of‐the‐art setup for concurrent TMS/fMRI is to use a large birdcage head coil, with the TMS between the subject's head and the MR coil. This setup has drawbacks in sensitivity, positioning, and available imaging techniques. In this study, an ultraslim 7‐channel receive‐only coil array for 3 T, which can be placed between the subject's head and the TMS, is presented. Interactions between the devices are investigated and the performance of the new setup is evaluated in comparison to the state‐of‐the‐art setup. Results MR sensitivity obtained at the depth of the TMS stimulation is increased by a factor of five. Parallel imaging with an acceleration factor of two is feasible with low g‐factors. Possible interactions between TMS and the novel hardware were investigated and were found negligible. Conclusion The novel coil array is safe, strongly improves signal‐to‐noise ratio in concurrent TMS/fMRI experiments, enables parallel imaging, and allows for flexible positioning of the TMS on the head while ensuring efficient TMS stimulation due to its ultraslim design. Magn Reson Med 74:1492–1501, 2015. © 2014 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Lucia I Navarro de Lara
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
| | - Christian Windischberger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
| | - Andre Kuehne
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
| | - Michael Woletz
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
| | - Jürgen Sieg
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
| | - Sven Bestmann
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, United Kingdom
| | - Nikolaus Weiskopf
- Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom
| | - Bernhard Strasser
- MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.,Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Ewald Moser
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
| | - Elmar Laistler
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
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11
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Yau JM, Jalinous R, Cantarero GL, Desmond JE. Static field influences on transcranial magnetic stimulation: considerations for TMS in the scanner environment. Brain Stimul 2014; 7:388-93. [PMID: 24656916 DOI: 10.1016/j.brs.2014.02.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 01/17/2014] [Accepted: 02/14/2014] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Transcranial magnetic stimulation (TMS) can be combined with functional magnetic resonance imaging (fMRI) to simultaneously manipulate and monitor human cortical responses. Although tremendous efforts have been directed at characterizing the impact of TMS on image acquisition, the influence of the scanner's static field on the TMS coil has received limited attention. OBJECTIVE/HYPOTHESIS The aim of this study was to characterize the influence of the scanner's static field on TMS. We hypothesized that spatial variations in the static field could account for TMS field variations in the scanner environment. METHODS Using an MRI-compatible TMS coil, we estimated TMS field strengths based on TMS-induced voltage changes measured in a search coil. We compared peak field strengths obtained with the TMS coil positioned at different locations (B0 field vs fringe field) and orientations in the static field. We also measured the scanner's static field to derive a field map to account for TMS field variations. RESULTS TMS field strength scaled depending on coil location and orientation with respect to the static field. Larger TMS field variations were observed in fringe field regions near the gantry as compared to regions inside the bore or further removed from the bore. The scanner's static field also exhibited the greatest spatial variations in fringe field regions near the gantry. CONCLUSIONS The scanner's static field influences TMS fields and spatial variations in the static field correlate with TMS field variations. Coil orientation changes in the B0 field did not result in substantial TMS field variations. TMS field variations can be minimized by delivering TMS in the bore or outside of the 0-70 cm region from the bore entrance.
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Affiliation(s)
- Jeffrey M Yau
- Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA.
| | | | - Gabriela L Cantarero
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA; Department of Physical Medicine and Rehabilitation, Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA
| | - John E Desmond
- Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA
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12
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Saito A, Takayama Y, Moriguchi H, Kotani K, Jimbo Y. Induced current pharmacological split stimulation system for neuronal networks. IEEE Trans Biomed Eng 2013; 61:463-72. [PMID: 24108746 DOI: 10.1109/tbme.2013.2281079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Magnetic stimulation noninvasively modulates neuronal activity through a magnetically induced current. However, despite the usefulness and popularity of this method, the effects of neuronal activity in the nonstimulated regions on the stimulus responses are unknown. Here, we report that the induced current-evoked responses were affected by neuronal activities in the nonstimulated regions. Our experiment used a Mu-metal-based localized induced current stimulation (LICS) system combined with the microfabricated cell culture chamber system and a microelectrode array (MEA). The cell culture chamber system has radiating microtunnels connecting one central and eight outer chambers, which were fabricated using soft lithography and a replica modeling technique with SU-8 photoresist and polydimethylsiloxane (PDMS). Rat cortical neurons were separately cultured in the chambers and formed functional synaptic connections through the microtunnels. By applying a biphasic alternating pulsed magnetic field to the Mu-metal located in the central chamber, induced currents were mainly generated near the cultured neurons and modified the neuronal activities, which were recorded through MEA. Furthermore, we confirmed that the evoked responses were modified by localized pharmacological stimulation (LPS) in the outer chambers. These results suggest that our system would be promising tool for analyzing the effect of magnetic stimulation on interacting neuronal activity.
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13
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Hanlon CA, Canterberry M, Taylor JJ, DeVries W, Li X, Brown TR, George MS. Probing the frontostriatal loops involved in executive and limbic processing via interleaved TMS and functional MRI at two prefrontal locations: a pilot study. PLoS One 2013; 8:e67917. [PMID: 23874466 PMCID: PMC3706588 DOI: 10.1371/journal.pone.0067917] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 05/21/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The prefrontal cortex (PFC) is an anatomically and functionally heterogeneous area which influences cognitive and limbic processing through connectivity to subcortical targets. As proposed by Alexander et al. (1986) the lateral and medial aspects of the PFC project to distinct areas of the striatum in parallel but functionally distinct circuits. The purpose of this preliminary study was to determine if we could differentially and consistently activate these lateral and medial cortical-subcortical circuits involved in executive and limbic processing though interleaved transcranial magnetic stimulation (TMS) in the MR environment. METHODS Seventeen healthy individuals received interleaved TMS-BOLD imaging with the coil positioned over the dorsolateral (EEG: F3) and ventromedial PFC (EEG: FP1). BOLD signal change was calculated in the areas directly stimulated by the coil and in subcortical regions with afferent and efferent connectivity to the TMS target areas. Additionally, five individuals were tested on two occasions to determine test-retest reliability. RESULTS Region of interest analysis revealed that TMS at both prefrontal sites led to significant BOLD signal increases in the cortex under the coil, in the striatum, and the thalamus, but not in the visual cortex (negative control region). There was a significantly larger BOLD signal change in the caudate following medial PFC TMS, relative to lateral TMS. The hippocampus in contrast was significantly more activated by lateral TMS. Post-hoc voxel-based analysis revealed that within the caudate the location of peak activity was in the ventral caudate following medial TMS and the dorsal caudate following lateral TMS. Test-retest reliability data revealed consistent BOLD responses to TMS within each individual but a large variation between individuals. CONCLUSION These data demonstrate that, through an optimized TMS/BOLD sequence over two unique prefrontal targets, it is possible to selectively interrogate the patency of these established cortical-subcortical networks in healthy individuals, and potentially patient populations.
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Affiliation(s)
- Colleen A Hanlon
- Department of Psychiatry, Medical University of South Carolina, Charleston, South Carolina, United States of America.
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Hernandez-Garcia L, Bhatia V, Prem-Kumar K, Ulfarsson M. Magnetic resonance imaging of time-varying magnetic fields from therapeutic devices. NMR IN BIOMEDICINE 2013; 26:718-724. [PMID: 23355446 PMCID: PMC3645268 DOI: 10.1002/nbm.2919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 11/26/2012] [Accepted: 12/16/2012] [Indexed: 06/01/2023]
Abstract
While magnetic resonance imaging of static magnetic fields generated by external probes has been previously demonstrated, there is an unmet need to image time-varying magnetic fields such as those generated by transcranial magnetic stimulators and radiofrequency hyperthermia probes. A method to image such time-varying magnetic fields is introduced in this study. This article presents the theory behind the method and provides proof of concept by imaging time-varying magnetic fields generated by a figure-eight coil inside simple phantoms over a range of frequencies and intensities using a 7T small animal MRI scanner. The method was able to reconstruct the three-dimensional components of the oscillating magnetic field vector.
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Bestmann S, Feredoes E. Combined neurostimulation and neuroimaging in cognitive neuroscience: past, present, and future. Ann N Y Acad Sci 2013; 1296:11-30. [PMID: 23631540 PMCID: PMC3760762 DOI: 10.1111/nyas.12110] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Modern neurostimulation approaches in humans provide controlled inputs into the operations of cortical regions, with highly specific behavioral consequences. This enables causal structure–function inferences, and in combination with neuroimaging, has provided novel insights into the basic mechanisms of action of neurostimulation on distributed networks. For example, more recent work has established the capacity of transcranial magnetic stimulation (TMS) to probe causal interregional influences, and their interaction with cognitive state changes. Combinations of neurostimulation and neuroimaging now face the challenge of integrating the known physiological effects of neurostimulation with theoretical and biological models of cognition, for example, when theoretical stalemates between opposing cognitive theories need to be resolved. This will be driven by novel developments, including biologically informed computational network analyses for predicting the impact of neurostimulation on brain networks, as well as novel neuroimaging and neurostimulation techniques. Such future developments may offer an expanded set of tools with which to investigate structure–function relationships, and to formulate and reconceptualize testable hypotheses about complex neural network interactions and their causal roles in cognition.
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Affiliation(s)
- Sven Bestmann
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, United Kingdom.
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Yau JM, Hua J, Liao DA, Desmond JE. Efficient and robust identification of cortical targets in concurrent TMS-fMRI experiments. Neuroimage 2013; 76:134-44. [PMID: 23507384 DOI: 10.1016/j.neuroimage.2013.02.077] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 02/06/2013] [Accepted: 02/28/2013] [Indexed: 11/28/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) can be delivered during fMRI scans to evoke BOLD responses in distributed brain networks. While concurrent TMS-fMRI offers a potentially powerful tool for non-invasively investigating functional human neuroanatomy, the technique is currently limited by the lack of methods to rapidly and precisely localize targeted brain regions - a reliable procedure is necessary for validly relating stimulation targets to BOLD activation patterns, especially for cortical targets outside of motor and visual regions. Here we describe a convenient and practical method for visualizing coil position (in the scanner) and identifying the cortical location of TMS targets without requiring any calibration or any particular coil-mounting device. We quantified the precision and reliability of the target position estimates by testing the marker processing procedure on data from 9 scan sessions: Rigorous testing of the localization procedure revealed minimal variability in coil and target position estimates. We validated the marker processing procedure in concurrent TMS-fMRI experiments characterizing motor network connectivity. Together, these results indicate that our efficient method accurately and reliably identifies TMS targets in the MR scanner, which can be useful during scan sessions for optimizing coil placement and also for post-scan outlier identification. Notably, this method can be used generally to identify the position and orientation of MR-compatible hardware placed near the head in the MR scanner.
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Affiliation(s)
- Jeffrey M Yau
- Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA.
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Jiang R, Jansen BH, Sheth BR, Chen J. Dynamic multi-channel TMS with reconfigurable coil. IEEE Trans Neural Syst Rehabil Eng 2012. [PMID: 23193321 DOI: 10.1109/tnsre.2012.2226914] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Investigations of the causal involvement of particular brain areas and interconnections in behavior require an external stimulation system with reasonable spatio-temporal resolution. Current transcranial magnetic stimulation (TMS) technology is limited to stimulating a single brain area once in a given trial. Here, we present a feasibility study for a novel TMS system based on multi-channel reconfigurable coils. With this hardware, researchers will be able to stimulate multiple brain sites in any temporal order in a trial. The system employs a wire-mesh coil, constructed using x- and y-directional wires. By varying the current direction and/or strength on each wire, we can configure the proposed mesh-wire coil into a standard loop coil and figure-eight coil of varying size. This provides maximum flexibility to the experimenter in that the location and extent of stimulation on the brain surface can be modified depending on experimental requirement. Moreover, one can dynamically and automatically modify the site(s) of stimulation several times within the span of seconds. By pre-storing various sequences of excitation patterns inside a control unit, one can explore the effect of dynamic TMS on behavior, in associative learning, and as rehabilitative therapy. Here, we present a computer simulation and bench experiments that show the feasibility of the dynamically-reconfigurable coil.
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Affiliation(s)
- Ruoli Jiang
- Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77204, USA
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18
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de Vries PM, de Jong BM, Bohning DE, Hinson VK, George MS, Leenders KL. Reduced parietal activation in cervical dystonia after parietal TMS interleaved with fMRI. Clin Neurol Neurosurg 2012; 114:914-21. [DOI: 10.1016/j.clineuro.2012.02.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 02/04/2012] [Accepted: 02/06/2012] [Indexed: 10/28/2022]
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Bungert A, Chambers CD, Phillips M, Evans CJ. Reducing image artefacts in concurrent TMS/fMRI by passive shimming. Neuroimage 2012; 59:2167-74. [DOI: 10.1016/j.neuroimage.2011.10.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 09/23/2011] [Accepted: 10/03/2011] [Indexed: 12/01/2022] Open
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Li X, Large CH, Ricci R, Taylor JJ, Nahas Z, Bohning DE, Morgan P, George MS. Using interleaved transcranial magnetic stimulation/functional magnetic resonance imaging (fMRI) and dynamic causal modeling to understand the discrete circuit specific changes of medications: lamotrigine and valproic acid changes in motor or prefrontal effective connectivity. Psychiatry Res 2011; 194:141-8. [PMID: 21924874 DOI: 10.1016/j.pscychresns.2011.04.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 04/27/2011] [Accepted: 04/28/2011] [Indexed: 10/17/2022]
Abstract
The purpose of this study was to use interleaved transcranial magnetic stimulation/functional magnetic resonance imaging (TMS/fMRI) to investigate the effects of lamotrigine (LTG) and valproic acid (VPA) on effective connectivity within motor and corticolimbic circuits. In this randomized, double-blind, crossover trial, 30 healthy volunteers received either drug or placebo 3.5 h prior to interleaved TMS/fMRI. We utilized dynamic causal modeling (DCM) to assess changes in the endogenous effective connectivity of bidirectional networks in the motor-sensory system and corticolimbic circuit. Results indicate that both LTG and VPA have network-specific effects. When TMS was applied over the motor cortex, both LTG and VPA reduced TMS-specific effective connectivity between primary motor (M1) and pre-motor cortex (PMd), and between M1 and the supplementary area motor (SMA). When TMS was applied over prefrontal cortex, however, LTG alone increased TMS-specific effective connectivity between the left dorsolateral prefrontal cortex(DLPFC) and the anterior cingulate cortex (ACC). In summary, LTG and VPA inhibited effective connectivity in motor circuits, but LTG alone increased effective connectivity in prefrontal circuits. These results suggest that interleaved TMS/fMRI can assess region- and circuit-specific effects of medications or interventions.
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Affiliation(s)
- Xingbao Li
- Department of Psychiatry, Medical University of South Carolina, Charleston, SC, USA.
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21
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Niskanen E, Julkunen P, Säisänen L, Vanninen R, Karjalainen P, Könönen M. Group-level variations in motor representation areas of thenar and anterior tibial muscles: Navigated Transcranial Magnetic Stimulation Study. Hum Brain Mapp 2010; 31:1272-80. [PMID: 20082330 DOI: 10.1002/hbm.20942] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Navigated transcranial magnetic stimulation (TMS) can be used to stimulate functional cortical areas at precise anatomical location to induce measurable responses. The stimulation has commonly been focused on anatomically predefined motor areas: TMS of that area elicits a measurable muscle response, the motor evoked potential. In clinical pathologies, however, the well-known homunculus somatotopy theory may not be straightforward, and the representation area of the muscle is not fixed. Traditionally, the anatomical locations of TMS stimulations have not been reported at the group level in standard space. This study describes a methodology for group-level analysis by investigating the normal representation areas of thenar and anterior tibial muscle in the primary motor cortex. The optimal representation area for these muscles was mapped in 59 healthy right-handed subjects using navigated TMS. The coordinates of the optimal stimulation sites were then normalized into standard space to determine the representation areas of these muscles at the group-level in healthy subjects. Furthermore, 95% confidence interval ellipsoids were fitted into the optimal stimulation site clusters to define the variation between subjects in optimal stimulation sites. The variation was found to be highest in the anteroposterior direction along the superior margin of the precentral gyrus. These results provide important normative information for clinical studies assessing changes in the functional cortical areas because of plasticity of the brain. Furthermore, it is proposed that the presented methodology to study TMS locations at the group level on standard space will be a suitable tool for research purposes in population studies.
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Affiliation(s)
- Eini Niskanen
- Department of Clinical Neurophysiology, Kuopio University Hospital, Finland.
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Interleaved transcranial magnetic stimulation and fMRI suggests that lamotrigine and valproic acid have different effects on corticolimbic activity. Psychopharmacology (Berl) 2010; 209:233-44. [PMID: 20195575 DOI: 10.1007/s00213-010-1786-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Accepted: 01/24/2010] [Indexed: 02/07/2023]
Abstract
RATIONALE Combined transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) can be used to study anticonvulsant drugs. A previous study showed that lamotrigine (LTG) inhibited brain activation induced when TMS was applied over motor cortex, whereas it increased activation induced by TMS applied over prefrontal cortex. OBJECTIVES The present double-blind, placebo-controlled, crossover study in 30 healthy subjects again combined TMS and fMRI to test whether the effects seen previously with LTG would be confirmed and to compare these with a second anticonvulsant drug, valproic acid (VPA). RESULTS Statistical parametric mapping analysis showed that both LTG and VPA, compared to placebo, inhibited TMS-induced activation of the motor cortex. In contrast, when TMS was applied over prefrontal cortex, LTG increased the activation of limbic regions, confirming previous results; VPA had no effect. CONCLUSION We conclude that LTG and VPA have similar inhibitory effects on motor circuits, but differing effects on the prefrontal corticolimbic system. The study demonstrates that a combination of TMS and fMRI techniques may be useful in the study of the effects of neuroactive drugs on specific brain circuits.
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Driver J, Blankenburg F, Bestmann S, Ruff CC. New approaches to the study of human brain networks underlying spatial attention and related processes. Exp Brain Res 2010; 206:153-62. [PMID: 20354681 PMCID: PMC2940032 DOI: 10.1007/s00221-010-2205-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Accepted: 02/18/2010] [Indexed: 11/29/2022]
Abstract
Cognitive processes, such as spatial attention, are thought to rely on extended networks in the human brain. Both clinical data from lesioned patients and fMRI data acquired when healthy subjects perform particular cognitive tasks typically implicate a wide expanse of potentially contributing areas, rather than just a single brain area. Conversely, evidence from more targeted interventions, such as transcranial magnetic stimulation (TMS) or invasive microstimulation of the brain, or selective study of patients with highly focal brain damage, can sometimes indicate that a single brain area may make a key contribution to a particular cognitive process. But this in turn raises questions about how such a brain area may interface with other interconnected areas within a more extended network to support cognitive processes. Here, we provide a brief overview of new approaches that seek to characterise the causal role of particular brain areas within networks of several interacting areas, by measuring the effects of manipulations for a targeted area on function in remote interconnected areas. In human participants, these approaches include concurrent TMS-fMRI and TMS-EEG, as well as combination of the focal lesion method in selected patients with fMRI and/or EEG measures of the functional impact from the lesion on interconnected intact brain areas. Such approaches shed new light on how frontal cortex and parietal cortex modulate sensory areas in the service of attention and cognition, for the normal and damaged human brain.
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Affiliation(s)
- Jon Driver
- Wellcome Trust Centre for Neuroimaging and UCL Institute of Cognitive Neuroscience, University College London, 12 Queen Square, London, UK
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Sparing R, Hesse MD, Fink GR. Neuronavigation for transcranial magnetic stimulation (TMS): Where we are and where we are going. Cortex 2010; 46:118-20. [DOI: 10.1016/j.cortex.2009.02.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 09/23/2008] [Accepted: 02/01/2009] [Indexed: 10/21/2022]
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Herbsman T, Avery D, Ramsey D, Holtzheimer P, Wadjik C, Hardaway F, Haynor D, George MS, Nahas Z. More lateral and anterior prefrontal coil location is associated with better repetitive transcranial magnetic stimulation antidepressant response. Biol Psychiatry 2009; 66:509-15. [PMID: 19545855 DOI: 10.1016/j.biopsych.2009.04.034] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 03/31/2009] [Accepted: 04/16/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND The left dorsolateral prefrontal cortex (DLPFC) is the most commonly used target for transcranial magnetic stimulation (TMS) in the treatment of depression. The "5-cm rule" is an empiric method used for probabilistic targeting of the DLPFC in most clinical trials. This rule may be suboptimal, as it does not account for differences in skull size or variations in prefrontal anatomy relative to motor cortex location. This study is a post hoc analysis of data from a large repetitive TMS (rTMS) trial in which we examined the variability of coil placement and how it affects antidepressant efficacy. METHODS Fifty-four depressed subjects enrolled in a randomized, single-site trial received either active rTMS or sham for 3 weeks. Prior to treatment initiation, investigators placed vitamin E capsules at the point of stimulation and used a high-resolution magnetic resonance imaging (MRI) scan to image these fiducials relative to anatomy. We employed a semiautomated imaging-processing algorithm to localize the cortical region stimulated. RESULTS Active TMS significantly reduced Hamilton Depression Rating Scale (HDRS) scores. A linear model for this improvement involving the coordinates of the stimulated cortex location, age, and treatment condition was highly significant. Specifically, individuals with more anterior and lateral stimulation sites were more likely to respond. CONCLUSIONS These results suggest that within the general anatomical area targeted by the 5-cm rule, placing the TMS coil more laterally and anteriorly is associated with improved response rates in TMS depression studies. Controlled studies testing this anatomical hypothesis are needed.
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Affiliation(s)
- Tal Herbsman
- Department of Psychiatry, Brain Stimulation Laboratory, Center for Advanced Imaging Research, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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de Vries PM, de Jong BM, Bohning DE, Walker JA, George MS, Leenders KL. Changes in cerebral activations during movement execution and imagery after parietal cortex TMS interleaved with 3T MRI. Brain Res 2009; 1285:58-68. [PMID: 19523932 DOI: 10.1016/j.brainres.2009.06.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2008] [Revised: 05/31/2009] [Accepted: 06/01/2009] [Indexed: 11/27/2022]
Abstract
The left parietal cortex contributes to goal-directed hand movement. In this study, we targeted this region with transcranial magnetic stimulation (TMS) to assess the effects on a wider distributed circuitry related to motor control. Ten healthy subjects underwent 3 Tesla functional magnetic resonance imaging (fMRI) with interleaved TMS. They either executed or imagined right wrist flexion/extension movements, which was preceded by a 10-second period either with or without TMS. This was applied to the left superior parietal cortex in 10 stimuli of 1 Hz at 115% motor threshold intensity. TMS preceding the movement execution condition resulted in significantly increased activation in the bilateral prefrontal, right temporo-parietal and left posterior parietal cortices, when compared to movement without such intervention (P<0.001 voxel-level; P<0.05, volume corrected). Movement imagery after TMS showed significantly increased activation in the left medial prefrontal cortex, right lateral prefrontal cortex, left supramarginal gyrus and right occipital cortex, while a decrease was present in bilateral anterior parietal cortex (P<0.01 voxel-level; P<0.05 volume corrected). Activation changes after TMS of left superior parietal cortex thus appears to increase prefrontal and posterior parietal cortex activation, associated with a reduced function of the anterior parietal cortex, including S2. These changes are thought to reflect an impaired ability to estimate the proprioceptive consequences of movement during its preparation, which is compensated by the increased contribution of more remote parietal and prefrontal cortical regions.
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Affiliation(s)
- Paulien M de Vries
- Department of Neurology, University Medical Center Groningen, Institute of Behavioral and Cognitive Neuroscience, University of Groningen, The Netherlands.
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Weiskopf N, Josephs O, Ruff CC, Blankenburg F, Featherstone E, Thomas A, Bestmann S, Driver J, Deichmann R. Image artifacts in concurrent transcranial magnetic stimulation (TMS) and fMRI caused by leakage currents: modeling and compensation. J Magn Reson Imaging 2009; 29:1211-7. [PMID: 19388099 PMCID: PMC3077517 DOI: 10.1002/jmri.21749] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2008] [Accepted: 02/04/2009] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To characterize and eliminate a new type of image artifact in concurrent transcranial magnetic stimulation and functional MRI (TMS-fMRI) caused by small leakage currents originating from the high-voltage capacitors in the TMS stimulator system. MATERIALS AND METHODS The artifacts in echo-planar images (EPI) caused by leakage currents were characterized and quantified in numerical simulations and phantom studies with different phantom-coil geometries. A relay-diode combination was devised and inserted in the TMS circuit that shorts the leakage current. Its effectiveness for artifact reduction was assessed in a phantom scan resembling a realistic TMS-fMRI experiment. RESULTS The leakage-current-induced signal changes exhibited a multipolar spatial pattern and the maxima exceeded 1% at realistic coil-cortex distances. The relay-diode combination effectively reduced the artifact to a negligible level. CONCLUSION The leakage-current artifacts potentially obscure effects of interest or lead to false-positives. Since the artifact depends on the experimental setup and design (eg, amplitude of the leakage current, coil orientation, paradigm, EPI parameters), we recommend its assessment for each experiment. The relay-diode combination can eliminate the artifacts if necessary.
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Affiliation(s)
- Nikolaus Weiskopf
- Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London, London, United Kingdom.
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Weiduschat N, Habedank B, Lampe B, Poggenborg J, Schuster A, Haupt WF, Heiss WD, Thiel A. Localizing Broca's area for transcranial magnetic stimulation: Comparison of surface distance measurements and stereotaxic positioning. Brain Stimul 2009; 2:93-102. [DOI: 10.1016/j.brs.2008.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 09/08/2008] [Accepted: 09/10/2008] [Indexed: 11/24/2022] Open
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Moisa M, Pohmann R, Ewald L, Thielscher A. New coil positioning method for interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) and its validation in a motor cortex study. J Magn Reson Imaging 2009; 29:189-97. [DOI: 10.1002/jmri.21611] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Muscles in "concert": study of primary motor cortex upper limb functional topography. PLoS One 2008; 3:e3069. [PMID: 18728785 PMCID: PMC2518106 DOI: 10.1371/journal.pone.0003069] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2008] [Accepted: 07/28/2008] [Indexed: 12/05/2022] Open
Abstract
Background Previous studies with Transcranial Magnetic Stimulation (TMS) have focused on the cortical representation of limited group of muscles. No attempts have been carried out so far to get simultaneous recordings from hand, forearm and arm with TMS in order to disentangle a ‘functional’ map providing information on the rules orchestrating muscle coupling and overlap. The aim of the present study is to disentangle functional associations between 12 upper limb muscles using two measures: cortical overlapping and cortical covariation of each pair of muscles. Interhemispheric differences and the influence of posture were evaluated as well. Methodology/Principal Findings TMS mapping studies of 12 muscles belonging to hand, forearm and arm were performed. Findings demonstrate significant differences between the 66 pairs of muscles in terms of cortical overlapping: extremely high for hand-forearm muscles and very low for arm vs hand/forearm muscles. When right and left hemispheres were compared, overlapping between all possible pairs of muscles in the left hemisphere (62.5%) was significantly higher than in the right one (53.5% ). The arm/hand posture influenced both measures of cortical association, the effect of Position being significant [p = .021] on overlapping, resulting in 59.5% with prone vs 53.2% with supine hand, but only for pairs of muscles belonging to hand and forearm, while no changes occurred in the overlapping of proximal muscles with those of more distal districts. Conclusions/Significance Larger overlapping in the left hemisphere could be related to its lifetime higher training of all twelve muscles studied with respect to the right hemisphere, resulting in larger intra-cortical connectivity within primary motor cortex. Altogether, findings with prone hand might be ascribed to mechanisms facilitating coupling of muscles for object grasping and lifting -with more proximal involvement for joint stabilization- compared to supine hand facilitating actions like catching. TMS multiple-muscle mapping studies permit a better understanding of motor control and ‘plastic’ reorganization of motor system.
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Sparing R, Buelte D, Meister IG, Paus T, Fink GR. Transcranial magnetic stimulation and the challenge of coil placement: a comparison of conventional and stereotaxic neuronavigational strategies. Hum Brain Mapp 2008; 29:82-96. [PMID: 17318831 PMCID: PMC6871049 DOI: 10.1002/hbm.20360] [Citation(s) in RCA: 207] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 11/13/2006] [Accepted: 12/07/2006] [Indexed: 11/07/2022] Open
Abstract
The combination of transcranial magnetic stimulation (TMS) with functional neuroimaging has expanded the potential of TMS for human brain mapping. The precise and reliable positioning of the TMS coil is not a simple task, however. Modern frameless stereotaxic systems allow investigators to base navigation either on the subject's structural magnetic resonance imaging (MRI), functional MRI data, or the use of functional neuroimaging data from the literature, so-called "probabilistic approach." The latter assumes consistency across individuals in the location of task-related "activations" in standardized stereotaxic space. Conventional nonstereotaxic localization of brain areas is also a common method for defining the coil position. Our aim was to evaluate the accuracy of five different localization strategies in one single study. The left primary motor cortex (left M1-Hand) was used as target region. Three approaches were based on real-time frameless stereotaxy using information based on either anatomical or functional MRI. The remaining two strategies relied either on standard cranial landmarks (i.e., the International 10-20 EEG system) or a standardized function-guided procedure (i.e., the spatial relationship between the left and right M1-Hand). The results were compared to a TMS-based mapping of the primary motor cortex; center of gravity of motor-evoked potentials (MEP-CoG) was calculated for each subject (n = 10). Our findings suggest that highest precision can be achieved with fMRI-guided stimulation, which was accurate within the range of millimeters. Very consistent results were also obtained with the "probabilistic" approach. In view of these findings, we discuss the methods and special characteristics of each localization strategy.
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Affiliation(s)
- Roland Sparing
- Department of Medicine, Institute of Neuroscience and Biophysics, Research Center Juelich, Juelich, Germany.
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Paine PA, Aziz Q, Gardener E, Hobson A, Mistry S, Thompson DG, Hamdy S. Assessing the temporal reproducibility of human esophageal motor-evoked potentials to transcranial magnetic stimulation. J Clin Neurophysiol 2006; 23:374-80. [PMID: 16885712 DOI: 10.1097/01.wnp.0000209578.08391.e2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Although the electrophysiological properties and reproducibility of somatic limb motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) are well characterized, little is known about the reproducibility of MEPs for viscerosomatic structures such as the esophagus. AIM To determine the temporal reproducibility of esophageal MEPs to TMS. METHODS MEPs to TMS were recorded from the proximal esophagus, using a swallowed catheter housing a pair of electrodes, in eight healthy subjects at five stimulus intensities (SI) (motor threshold [MT] to 20% above MT). For each SI, 20 consecutive TMS stimuli at 5-second intervals were delivered over a single scalp site (dominant hemisphere at site exhibiting MT at lowest SI) and repeated 40 and 80 minutes thereafter. MEP amplitudes and latencies were measured, and means were sequentially calculated for each SI and then log-transformed. The repeatability coefficients (RC) for the three time points were calculated across each set of 20 stimuli and presented as an exponential ratio. RESULTS Best RC (amplitude/latency) were achieved at 120% SI relative to MT, being 1.8/1.2 (optimal = 1.0). For lower intensities of 115%, 110%, 105%, and 100% SI, the RC were 2.1/1.2, 2.1/1.1, 2.4/1.2, and 2.6/1.4, respectively. For all SI, the greatest reductions in RC occurred over the first 10 stimuli, with little additional gain beyond this number. CONCLUSIONS Latencies of esophageal MEP to TMS across intensities are highly reproducible, whereas amplitudes are more stimulus intensity-dependent, being most reliable and reproducible at the highest stimulus strengths. SIGNIFICANCE Using careful parameters, TMS can be used reliably in future studies of viscerosomatic structures, although the size of the response variability needs to be taken into account when assessing changes in cortico-fugal activity.
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Affiliation(s)
- P A Paine
- Department of Gastrointestinal Sciences and Statistics, Hope Hospital, Salford, University of Manchester, United Kingdom
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Abstract
It is increasingly recognized that there are a heterogeneous range of symptoms within the syndrome of schizophrenia and that some of these also occur frequently within other psychiatric conditions. An approach similar to that in neuropsychology, where cases are grouped based on a discrete deficit, or in this case a discrete symptom, rather than a cause or diagnosis, may be useful in exploring the neural correlates of psychotic symptomatology. Functional neuroimaging provides an excellent tool for investigating the in vivo cortical function of patients with schizophrenia. Auditory verbal hallucinations are one of the most commonly occurring psychotic symptoms in schizophrenia; and this paper examines the progress that has been made in utilizing neuroimaging techniques to investigate auditory hallucinations in schizophrenia and review potential implications for treatment and future directions for research.
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Affiliation(s)
- D K Tracy
- 1Department of Psychological Medicine, Division of Psychological Medicine, Institute of Psychiatry, Kings College London, London, UK
| | - S S Shergill
- 1Department of Psychological Medicine, Division of Psychological Medicine, Institute of Psychiatry, Kings College London, London, UK
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Denslow S, Bohning DE, Bohning PA, Lomarev MP, George MS. An increased precision comparison of TMS-induced motor cortex BOLD fMRI response for image-guided versus function-guided coil placement. Cogn Behav Neurol 2005; 18:119-26. [PMID: 15970732 DOI: 10.1097/01.wnn.0000160821.15459.68] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To examine with high precision the differences between function-guided and image-guided transcranial magnetic stimulation (TMS). METHOD Using a calibrated TMS coil holder/positioner, interleaved TMS/functional magnetic resonance imaging (fMRI), and individualized anatomy-based regional normalization, we conducted a two-phase study of TMS coil positioning guided by either function (elicited thumb motion) or image-based targeting of the "hand knob," the anatomy associated with fMRI activation during thumb motion. RESULTS In every case, image-guided TMS coil placement produced a thumb movement response at thresholds similar to those found under function guidance. Unexpectedly, function-guided coil locations clustered bimodally over central and precentral sulci. Image-guided locations clustered as anticipated toward the targeted gyral crown. Despite these differences, blood oxygenation level-dependent (BOLD) activation locations and magnitude for the two methods displayed no consistent differences in mean or variance between or within subjects. Image guidance produced more consistent coil placement from subject to subject relative to targeted anatomy. Surprisingly, BOLD time courses from image-guided experiments showed significantly slower return to baseline after TMS than was observed under function guidance. CONCLUSIONS The results demonstrate the effectiveness and precision of image-guided positioning of TMS coils combined with a precisely adjustable holder/positioner and regional normalization. Image guidance provides an accurate TMS placement relative to individual anatomy when no external sign is available.
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Affiliation(s)
- Stewart Denslow
- Department of Radiology, Center for Advanced Imaging Research and Brain Stimulation Laboratories, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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Abstract
Transcranial magnetic stimulation (TMS) is a patient-friendly stimulation technique of the brain with interesting perspectives. In clinical psychiatry, limited data are available on activity in psychosis and anxiety, but much research has been done in depression. Major concerns on published papers are the inconsistency of used parameter settings, the restraint numbers of patients in randomised trials, the lack of real sham controlled studies and the quasi inexistent reproducibility of results. The most stringent meta-analysis of TMS in affective disorders found a modest, statistically significant antidepressant effect after 2 weeks of daily treatment of high frequency repetitive left dorsolateral prefrontal cortex stimulation. Although most results are rather weak and not convincing enough to promote TMS as evidence-based antidepressive therapy, they show a measurable action that should not be ignored. Preclinical and clinical effects were observed analysing heterogeneous data, and results comparing TMS to electroconvulsive therapy (ECT) in affective disorders are encouraging. Efforts should continue with emphasis on increasing homogeneity and reproducibility in data. Further refinement of stimulation parameters should be established, so that new and large double-blind, long-term, sham-controlled trials can bring us to better understanding and standardising TMS procedure, finally leading to definitive conclusions about its efficacy in psychiatry.
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Affiliation(s)
- Wim Simons
- University Centre St. Jozef, Catholic University of Leuven, Kortenberg, Belgium
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Niyazov DM, Butler AJ, Kadah YM, Epstein CM, Hu XP. Functional magnetic resonance imaging and transcranial magnetic stimulation: effects of motor imagery, movement and coil orientation. Clin Neurophysiol 2005; 116:1601-10. [PMID: 15953559 DOI: 10.1016/j.clinph.2005.02.028] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2004] [Revised: 01/18/2005] [Accepted: 02/21/2005] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To compare fMRI activations during movement and motor imagery to corresponding motor evoked potential (MEP) maps obtained with the TMS coil in three different orientations. METHODS fMRI activations during executed (EM) and imagined (IM) movements of the index finger were compared to MEP maps of the first dorsal interosseus (FDI) muscle obtained with the TMS coil in anterior, posterior and lateral handle positions. To ensure spatial registration of fMRI and MEP maps, a special grid was used in both experiments. RESULTS No statistically significant difference was found between the TMS centers of gravity (TMS CoG) obtained with the three coil orientations. There was a significant difference between fMRI centers of gravity during IMs (IM CoG) and EMs (EM CoG), with IM CoGs localized on average 10.3mm anterior to those of EMs in the precentral gyrus. Most importantly, the IM CoGs closely matched cortical projections of the TMS CoGs while the EM CoGs were on average 9.5mm posterior to the projected TMS CoGs. CONCLUSIONS TMS motor maps are more congruent with fMRI activations during motor imagery than those during EMs. These findings are not significantly affected by changing orientation of the TMS coil. SIGNIFICANCE Our results suggest that the discrepancy between fMRI and TMS motor maps may be largely due to involvement of the somatosensory component in the EM task.
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Affiliation(s)
- D M Niyazov
- Department of Biomedical Engineering, Emory University School of Medicine, Hospital Annex, 531 Asbury Circle, Suite N305, Atlanta, GA 30322, USA.
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Denslow S, Lomarev M, George MS, Bohning DE. Cortical and subcortical brain effects of transcranial magnetic stimulation (TMS)-induced movement: an interleaved TMS/functional magnetic resonance imaging study. Biol Psychiatry 2005; 57:752-60. [PMID: 15820232 DOI: 10.1016/j.biopsych.2004.12.017] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2004] [Revised: 12/06/2004] [Accepted: 12/09/2004] [Indexed: 11/19/2022]
Abstract
BACKGROUND To date, interleaved transcranial magnetic stimulation and functional magnetic resonance imaging (TMS/fMRI) studies of motor activation have not recorded whole brain patterns. We hypothesized that TMS would activate known motor circuitry with some additional regions plus some areas dropping out. METHODS We used interleaved TMS/fMRI (11 subjects, three scans each) to elucidate whole brain activation patterns from 1-Hz TMS over left primary motor cortex. RESULTS Both TMS (110% motor threshold) and volitional movement of the same muscles excited by TMS caused blood oxygen level-dependent (BOLD) patterns encompassing known motor circuitry. Additional activation was observed bilaterally in superior temporal auditory areas. Decreases in BOLD signal with unexpected post-task "rebounds" were observed for both tasks in the right motor area, right superior parietal lobe, and in occipital regions. Paired t test of parametric contrast maps failed to detect significant differences between TMS- and volition-induced effects. Differences were detectable, however, in primary data time-intensity profiles. CONCLUSIONS Using this interleaved TMS/fMRI technique, TMS over primary motor cortex produces a whole brain pattern of BOLD activation similar to known motor circuitry, without detectable differences from mimicked volitional movement. Some differences may exist between time courses of BOLD intensity during TMS circuit activation and volitional circuit activation.
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Affiliation(s)
- Stewart Denslow
- Department of Radiology, Center for Advanced Imaging Research and Brain Stimulation Laboratories, Medical University of South Carolina, Charlestown, SC 29425, USA.
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Kozel FA, Nahas Z, Bohning DE, George MS. Functional Magnetic Resonance Imaging and Transcranial Magnetic Stimulation for Major Depression. Psychiatr Ann 2005. [DOI: 10.3928/00485713-20050201-05] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Denslow S, Lomarev M, Bohning DE, Mu Q, George MS. A High Resolution Assessment of the Repeatability of Relative Location and Intensity of Transcranial Magnetic Stimulation–induced and Volitionally Induced Blood Oxygen Level–dependent Response in the Motor Cortex. Cogn Behav Neurol 2004; 17:163-73. [PMID: 15536304 DOI: 10.1097/01.wnn.0000117864.42205.6d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Using functional magnetic resonance imaging, we assessed variation in location and intensity of blood oxygen level-dependent contrast associated with movements induced by transcranial magnetic stimulation or volition. BACKGROUND Anatomic location and within-subject repeatability of blood oxygen level-dependent responses induced by transcranial magnetic stimulation comprise critical information to the use of interleaved transcranial magnetic stimulation/functional magnetic resonance imaging as a neuroscience tool. METHODS Eleven healthy adults were scanned 3 times each at 1.5 T. Interleaved with functional magnetic resonance imaging, 1-Hz transcranial magnetic stimulation was applied over motor cortex. VOL was alternated with transcranial magnetic stimulation over the scans. RESULTS Intra-subject standard deviations in blood oxygen level-dependent locations ranged between 3 and 6 millimeters, allowing localization to subregions of the motor strip. Coil placement relative to blood oxygen level-dependent location varied more than blood oxygen level-dependent location (sdx = 9.5mm, sdy = 8.7 mm, sdz = 9.0mm) with consistent anterior displacement (dy = 21.8 mm, P = <0.025). Analysis of variance did not detect significant differences between transcranial magnetic stimulation and VOL blood oxygen level-dependent locations or intensities, in contrast to significant intensity differences detected in auditory blood oxygen level dependence. CONCLUSION The high repeatability of location of transcranial magnetic stimulation-induced blood oxygen level-dependent activation suggests that transcranial magnetic stimulation/functional magnetic resonance imaging stimulation can be used as a precise tool in investigation of cortical mechanisms. The similarity between VOL and transcranial magnetic stimulation suggests that transcranial magnetic stimulation may act through natural brain movement circuits.
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Affiliation(s)
- Stewart Denslow
- Center for Advanced Imaging Research and Brain Stimulation Laboratories, Department of Radiology, Medical University of South Carolina, Charleston, South Carolina, USA
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Li X, Tenebäck CC, Nahas Z, Kozel FA, Large C, Cohn J, Bohning DE, George MS. Interleaved transcranial magnetic stimulation/functional MRI confirms that lamotrigine inhibits cortical excitability in healthy young men. Neuropsychopharmacology 2004; 29:1395-407. [PMID: 15100699 DOI: 10.1038/sj.npp.1300452] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Little is known about how lamotrigine (LTG) works within brain circuits to achieve its clinical effects. We wished to determine whether the new technique of interleaved transcranial magnetic stimulation (TMS)/functional magnetic resonance imaging (fMRI) could be used to assess the effects of LTG on activated motor or prefrontal/limbic circuits. We carried out a randomized, double-blind, crossover trial involving two visits 1 week apart with TMS measures of cortical excitability and blood oxygen level-dependent TMS/fMRI. Subjects received either a single oral dose of 325 mg of LTG or placebo on each visit. In all, 10 subjects provided a complete data set that included interleaved TMS/fMRI measures and resting motor threshold (rMT) determinations under both placebo and LTG conditions. A further two subjects provided only rMT data under the two drug conditions. LTG caused a 14.9+/-9.6% (mean+/-SD) increase in rMT 3 h after the drug, compared with a 0.6+/-10.9% increase 3 h after placebo (t=3.41, df =11, p<0.01). fMRI scans showed that LTG diffusely inhibited cortical activation induced by TMS applied over the motor cortex. In contrast, when TMS was applied over the prefrontal cortex, LTG increased the TMS-induced activation of limbic regions, notably the orbitofrontal cortex and hippocampus. These results suggest that LTG, at clinically relevant serum concentrations, has a general inhibitory effect on cortical neuronal excitability, but may have a more complex effect on limbic circuits. Furthermore, the interleaved TMS/fMRI technique may be a useful tool for investigating regional brain effects of psychoactive compounds.
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Affiliation(s)
- Xingbao Li
- Brain Stimulation Laboratory, Center for Advanced Imaging Research (CAIR), Medical University of South Carolina (MUSC), Charleston, SC 29425, USA.
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Bestmann S, Baudewig J, Siebner HR, Rothwell JC, Frahm J. Functional MRI of the immediate impact of transcranial magnetic stimulation on cortical and subcortical motor circuits. Eur J Neurosci 2004; 19:1950-62. [PMID: 15078569 DOI: 10.1111/j.1460-9568.2004.03277.x] [Citation(s) in RCA: 320] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent studies indicate that the cortical effects of transcranial magnetic stimulation (TMS) may not be localized to the site of stimulation, but spread to other distant areas. Using echo-planar imaging with blood-oxygenation-level-dependent (BOLD) contrast at 3 Tesla, we measured MRI signal changes in cortical and subcortical motor regions during high-frequency (3.125 Hz) repetitive TMS (rTMS) of the left sensorimotor cortex (M1/S1) at intensities above and below the active motor threshold in healthy humans. The supra- and subthreshold nature of the TMS pulses was confirmed by simultaneous electromyographic monitoring of a hand muscle. Suprathreshold rTMS activated a network of primary and secondary cortical motor regions including M1/S1, supplementary motor area, dorsal premotor cortex, cingulate motor area, the putamen and thalamus. Subthreshold rTMS elicited no MRI-detectable activity in the stimulated M1/S1, but otherwise led to a similar activation pattern as obtained for suprathreshold stimulation though at reduced intensity. In addition, we observed activations within the auditory system, including the transverse and superior temporal gyrus, inferior colliculus and medial geniculate nucleus. The present findings support the notion that re-afferent feedback from evoked movements represents the dominant input to the motor system via M1 during suprathreshold stimulation. The BOLD MRI changes in motor areas distant from the site of subthreshold stimulation are likely to originate from altered synaptic transmissions due to induced excitability changes in M1/S1. They reflect the capability of rTMS to target both local and remote brain regions as tightly connected constituents of a cortical and subcortical network.
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Affiliation(s)
- Sven Bestmann
- Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, 37077 Göttingen, Germany.
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Sandrini M, Rossini PM, Miniussi C. The differential involvement of inferior parietal lobule in number comparison: a rTMS study. Neuropsychologia 2004; 42:1902-9. [PMID: 15381020 DOI: 10.1016/j.neuropsychologia.2004.05.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Revised: 05/17/2004] [Accepted: 05/19/2004] [Indexed: 11/19/2022]
Abstract
Number processing is known to involve several sites within the posterior regions of parietal cortex. Here, we investigated whether neural activity in the inferior parietal lobule (IPL) is essential for number processing, by observing the effects of interfering with its activity during the execution of a standard number comparison task. Subjects performance on the task was significantly slowed down when we delivered trains of repetitive transcranial magnetic stimuli (rTMS) to the posterior parietal scalp site overlying the left IPL, while rTMS did not affect the number comparison task if delivered to homologous, contralateral (right) IPL. In conclusion, the present findings add support to a growing body of evidence from neuropsychology and neuroimaging studies that the left inferior parietal lobule is an important component of the networks subserving the representation of quantity.
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Affiliation(s)
- Marco Sandrini
- IRCCS S. Giovanni di Dio Fatebenefratelli, Via Pilastroni 4, 25123 Brescia, Italy.
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Siebner HR, Lee L, Bestmann S. Interleaving TMS with functional MRI: now that it is technically feasible how should it be used? Clin Neurophysiol 2003; 114:1997-9. [PMID: 14580597 DOI: 10.1016/s1388-2457(03)00242-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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