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157 results on '"Souza, Victor H."'

9. Modeling the stress and forces on multi-channel TMS coil arrays in high-field MRI scanners.

Author

Koponen, Maria A, Korhonen, Juuso T, Vilchez Membrilla, José A, Sinisalo, Heikki, Paasonen, Jaakko, Cobos Sánchez, Clemente, Gröhn, Olli, Ilmoniemi, Risto J, and Souza, Victor H

Subjects
TRANSCRANIAL magnetic stimulation, FUNCTIONAL magnetic resonance imaging, STRUCTURAL failures, FINITE element method, STRESS concentration
Abstract

Transcranial magnetic stimulation (TMS) is a non-invasive method for stimulating the cortex. Concurrent functional magnetic resonance imaging can show changes in TMS-induced activity in the whole brain, with the potential to inform brain function research and to guide the development of TMS therapy. However, the interaction of the strong current pulses in the TMS coil in the static main magnetic field of the MRI produces high Lorentz forces, which may damage the coil enclosure and compromise the patient's safety. We studied the time-dependent mechanical behavior and durability of two multi-locus TMS (mTMS) coil arrays inside a high-field MRI bore with finite element modeling. In addition, coil arrays were built and tested based on the simulation results. We found that the current pulses produce shock waves and time-dependent stress distribution in the coil plates. The intensity and location of the maximum stress depend on the current waveform, the coil combination, and the transducer orientation relative to the MRI magnetic field. We found that 30% glass-fiber-filled polyamide is the most durable material out of the six options studied. In addition, novel insights for more durable TMS coil designs were obtained. Our study contributes to a comprehensive understanding of the underlying mechanisms responsible for the structural failure of mTMS coil arrays during stimulation within high static magnetic fields. This knowledge is essential for developing mechanically stable and safe mTMS-MRI transducers. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Clarifying Glycerol Electrooxidation Studies on Pd‐Based Catalysts: Insights Into Catalytic Performance and Practical Challenges.

Author

Zanata, Cinthia R., Alencar, Leticia M., Santos, Alexandre B., Souza, Victor H. R., Camara, Giuseppe A., and Martins, Cauê A.

Subjects
METAL catalysts, CATALYTIC activity, PRECIOUS metals, CATALYSTS, INDUSTRIAL applications
Abstract

Escalating biodiesel production led to a surplus of glycerol, prompting its exploration as a valuable resource in industrial applications. Electrochemical systems have been studied, specifically employing noble metal catalysts like palladium for glycerol electrooxidation. Despite numerous studies on Pd‐based catalysts for glycerol electrooxidation, a comprehensive analysis addressing critical questions related to the economic feasibility, global sourcing of Pd, and the thematic cohesion of publications in this field is lacking. Moreover, a standardized framework for comparing the results of various studies is absent, hindering progress on glycerol technologies. This critical overview navigates the evolution of Pd‐based catalysts for glycerol electrooxidation, examining catalytic activity, stability, and potential applications. It critically addresses the geographical sources of Pd, the motivation behind glycerol technology exploration, thematic coherence in existing publications, and the meaningful comparison of results. It correlates the use of Pd‐based catalysts with the natural source of Pd and the origin of glycerol derived from biodiesel. The proposed standardized approach for comparing electrochemical parameters and establishing experimental protocols provides a foundation for meaningful study comparisons. This critical overview underscores the need to address fundamental questions to accelerate the transition of glycerol technologies from laboratories to practical applications. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Characterizing an electronic–robotic targeting platform for precise and fast brain stimulation with multi-locus transcranial magnetic stimulation

Author

Matsuda, Renan H., primary, Souza, Victor H., additional, Marchetti, Thais C., additional, Soto, Ana M., additional, Kahilakoski, Olli-Pekka, additional, Laine, Mikael, additional, Sinisalo, Heikki, additional, Kicic, Dubravko, additional, Lioumis, Pantelis, additional, Ilmoniemi, Risto J., additional, and Baffa, Oswaldo, additional

Published
2024
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14. Individualized treatment of motor stroke: a perspective on open-loop, closed-loop and adaptive closed-loop brain state-dependent TMS

Author

Rösch, Johanna, primary, Emanuel Vetter, David, additional, Baldassarre, Antonello, additional, Souza, Victor H., additional, Lioumis, Pantelis, additional, Roine, Timo, additional, Jooß, Andreas, additional, Baur, David, additional, Kozák, Gábor, additional, Blair Jovellar, D., additional, Vaalto, Selja, additional, Luca Romani, Gian, additional, Ilmoniemi, Risto J., additional, and Ziemann, Ulf, additional

Published
2023
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15. Towards real-time identification of large-scale brain states for improved brain state-dependent stimulation

Author

Marzetti, Laura, primary, Makkinayeri, Saeed, additional, Pieramico, Giulia, additional, Guidotti, Roberto, additional, D'Andrea, Antea, additional, Roine, Timo, additional, Mutanen, Tuomas P., additional, Souza, Victor H., additional, Kičić, Dubravko, additional, Baldassarre, Antonello, additional, Ermolova, Maria, additional, Pankka, Hanna, additional, Ilmoniemi, Risto J., additional, Ziemann, Ulf, additional, Luca Romani, Gian, additional, and Pizzella, Vittorio, additional

Published
2023
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20. Modulating brain networks in space and time: Multi-locus transcranial magnetic stimulation

Author

Sinisalo, Heikki, Rissanen, Ilkka, Kahilakoski, Olli-Pekka, Souza, Victor H., Tommila, Timo, Laine, Mikael, Nyrhinen, Mikko, Ukharova, Elena, Granö, Ida, Soto, Ana M., Matsuda, Renan H., Rantala, Robin, Guidotti, Roberto, Kičić, Dubravko, Lioumis, Pantelis, Mutanen, Tuomas, Pizzella, Vittorio, Marzetti, Laura, Roine, Timo, Stenroos, Matti, Ziemann, Ulf, Romani, Gian Luca, and Ilmoniemi, Risto J.

Published
2024
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23. TMS-Induced Modulation of EEG Functional Connectivity Is Affected by the E-Field Orientation

Author

Pieramico, Giulia, primary, Guidotti, Roberto, additional, Nieminen, Aino E., additional, D’Andrea, Antea, additional, Basti, Alessio, additional, Souza, Victor H., additional, Nieminen, Jaakko O., additional, Lioumis, Pantelis, additional, Ilmoniemi, Risto J., additional, Romani, Gian Luca, additional, Pizzella, Vittorio, additional, and Marzetti, Laura, additional

Published
2023
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24. Connecting to brain networks using multi-channel TMS and EEG

Author

Ilmoniemi, Risto J., primary, Nieminen, Jaakko O., additional, Nieminen, Aino E., additional, Koponen, Lari M., additional, Sinisalo, Heikki, additional, Souza, Victor H., additional, Korhonen, Juuso T., additional, Lioumis, Pantelis, additional, Kahilakoski, Olli-Pekka, additional, and Aydogan, Dogu Baran, additional

Published
2023
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29. Accurate and precise digital real-time control of transcranial magnetic stimulation

Author

Kahilakoski, Olli-Pekka, primary, Sinisalo, Heikki, additional, Nieminen, Jaakko O., additional, Valén, Kim, additional, Alkio, Kyösti, additional, Aydogan, Dogu Baran, additional, Guidotti, Roberto, additional, Kičić, Dubravko, additional, Matsuda, Renan, additional, Soto, Ana, additional, Souza, Victor H., additional, Roine, Timo, additional, and Ilmoniemi, Risto J., additional

Published
2023
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30. Self-driving TMS: the future is now!

Author

Kičić, Dubravko, primary, Ilmoniemi, Risto J., additional, Nieminen, Jaakko, additional, Nieminen, Aino, additional, Koponen, Lari M., additional, Sinisalo, Heikki, additional, Souza, Victor H., additional, Korhonen, Juuso, additional, Lioumis, Pantelis, additional, and Kahilakoski, Olli-Pekka, additional

Published
2023
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31. Local brain-state dependency of effective connectivity : A pilot TMS-EEG study [version 2; peer review: 2 approved]

Author

Granö, Ida, Mutanen, Tuomas P., Tervo, Aino, Nieminen, Jaakko O., Souza, Victor H., Fecchio, Matteo, Rosanova, Mario, Lioumis, Pantelis, Ilmoniemi, Risto J., BioMag Laboratory, HUS Medical Imaging Center, and Helsinki University Hospital Area

Subjects
Transcranial magnetic stimulation, electroencephalography, brain state, effective connectivity, 3126 Surgery, anesthesiology, intensive care, radiology
Abstract

Publisher Copyright: © 2022 Granö I et al. Background: Spontaneous cortical oscillations have been shown to modulate cortical responses to transcranial magnetic stimulation (TMS). However, whether these oscillations influence cortical effective connectivity is largely unknown. We conducted a pilot study to set the basis for addressing how spontaneous oscillations affect cortical effective connectivity measured through TMS-evoked potentials (TEPs). Methods: We applied TMS to the left primary motor cortex and right pre-supplementary motor area of three subjects while recording EEG. We classified trials off-line into positive- and negative-phase classes according to the mu and beta rhythms. We calculated differences in the global mean-field amplitude (GMFA) and compared the cortical spreading of the TMS-evoked activity between the two classes. Results: Phase affected the GMFA in four out of 12 datasets (3 subjects × 2 stimulation sites × 2 frequency bands). Two of the observed significant intervals were before 50 ms, two between 50 and 100 ms, and one after 100 ms post-stimulus. Source estimates showed complex spatial differences between the classes in the cortical spreading of the TMS-evoked activity. Conclusions: TMS-evoked effective connectivity seems to depend on the phase of local cortical oscillations at the stimulated site. This work paves the way to design future closed-loop stimulation paradigms.

Published
2022

32. A tunable color palette of electrochromic materials achieved through an ingenious stacking of ordinary conducting polymers.

Author

Souza, Victor H. R., Schmidt, Ariane, and Zarbin, Aldo J. G.

Abstract

Obtaining a wide color gamut and controllable color switching of electrochromic polymers (ECPs) is crucial for advanced applications. In this study, we present a multicolor palette of ECPs based on thin and transparent films of three ordinary conducting polymers: polythiophene (red), polyaniline (green), and poly(3,4-ethylenedioxythiophene) (blue). We utilized the liquid/liquid interfacial route to produce the polymer films and achieved different color tones by stacking them in varying combinations and/or numbers of layers. Thirteen distinct colors, covering the fully visible spectrum, were prepared, and their electrochromic properties were demonstrated. Fine-tuning of the colors is possible by carefully selecting the stacked samples and applying voltage. Finally, we create a rainbow-like, multicolored electrode to showcase the potential of this technique in producing multifunctional and spatially controlled electrodes for advanced electrochromic technologies. [ABSTRACT FROM AUTHOR]

Published
2023
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33. TU-131. Whole-brain structural connectivity affects TMS–EEG signal propagation

Author

Ukharova, Elena, primary, Lioumis, Pantelis, additional, Tervo, Aino E., additional, Nieminen, Jaakko O., additional, Granö, Ida, additional, Baran Aydogan, Dogu, additional, Mutanen, Tuomas P., additional, Souza, Victor H., additional, Fecchio, Matteo, additional, Rosanova, Mario, additional, Ilmoniemi, Risto J., additional, and Roine, Timo, additional

Published
2022
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36. Effect of stimulus orientation and intensity on short-interval intracortical inhibition (SICI) and facilitation (SICF)

Author

Tugin, Sergei, Souza, Victor H., Nazarova, Maria A., Novikov, Pavel A., Tervo, Aino E., Nieminen, Jaakko O., Lioumis, Pantelis, Ziemann, Ulf, Nikulin, Vadim V., Ilmoniemi, Risto J., Department of Neuroscience and Biomedical Engineering, Higher School of Economics, University of Tübingen, Aalto-yliopisto, and Aalto University

Abstract

openaire: EC/H2020/810377/EU//ConnectToBrain Besides stimulus intensities and interstimulus intervals (ISI), the electric field (E-field) orientation is known to affect both short-interval intracortical inhibition (SICI) and facilitation (SICF) in paired-pulse transcranial magnetic stimulation (TMS). However, it has yet to be established how distinct orientations of the conditioning (CS) and test stimuli (TS) affect the SICI and SICF generation. With the use of a multi-channel TMS transducer that provides electronic control of the stimulus orientation and intensity, we aimed to investigate how changes in the CS and TS orientation affect the strength of SICI and SICF. We hypothesized that the CS orientation would play a major role for SICF than for SICI, whereas the CS intensity would be more critical for SICI than for SICF. In eight healthy subjects, we tested two ISIs (1.5 and 2.7 ms), two CS and TS orientations (anteromedial (AM) and posteromedial (PM)), and four CS intensities (50, 70, 90, and 110% of the resting motor threshold (RMT)). The TS intensity was fixed at 110% RMT. The intensities were adjusted to the corresponding RMT in the AM and PM orientations. SICI and SICF were observed in all tested CS and TS orientations. SICI depended on the CS intensity in a U-shaped manner in any combination of the CS and TS orientations. With 70% and 90% RMT CS intensities, stronger PM-oriented CS induced stronger inhibition than weaker AM-oriented CS. Similar SICF was observed for any CS orientation. Neither SICI nor SICF depended on the TS orientation. We demonstrated that SICI and SICF could be elicited by the CS perpendicular to the TS, which indicates that these stimuli affected either overlapping or strongly connected neuronal populations. We concluded that SICI is primarily sensitive to the CS intensity and that CS intensity adjustment resulted in similar SICF for different CS orientations.

Published
2021

37. Effect of stimulus orientation and intensity on short-interval intracortical inhibition (SICI) and facilitation (SICF) : A multi-channel transcranial magnetic stimulation study

Author

Tugin, Sergei, Souza, Victor H., Nazarova, Maria A., Novikov, Pavel A., Tervo, Aino E., Nieminen, Jaakko O., Lioumis, Pantelis, Ziemann, Ulf, Nikulin, Vadim V., Ilmoniemi, Risto J., BioMag Laboratory, and HUS Medical Imaging Center

Subjects
Adult, Male, Physiology, Science, Social Sciences, Neurophysiology, Research and Analysis Methods, Nervous System, Membrane Potential, 3124 Neurology and psychiatry, Young Adult, Animal Cells, Interneurons, Behavioral Conditioning, Neural Pathways, Medicine and Health Sciences, Psychology, Humans, Transcranial Stimulation, Evoked Potentials, Neurons, Behavior, Brain Mapping, Motor Evoked Potentials, Electromyography, Electrophysiological Techniques, Motor Cortex, 3112 Neurosciences, Biology and Life Sciences, Brain, Neural Inhibition, Cell Biology, Evoked Potentials, Motor, Transcranial Magnetic Stimulation, Healthy Volunteers, Electrophysiology, Neuroanatomy, Bioassays and Physiological Analysis, Brain Electrophysiology, Cellular Neuroscience, Medicine, Cellular Types, Anatomy, Muscle Electrophysiology, Research Article, Neuroscience
Abstract

Publisher Copyright: © 2021 Tugin et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Besides stimulus intensities and interstimulus intervals (ISI), the electric field (E-field) orientation is known to affect both short-interval intracortical inhibition (SICI) and facilitation (SICF) in paired-pulse transcranial magnetic stimulation (TMS). However, it has yet to be established how distinct orientations of the conditioning (CS) and test stimuli (TS) affect the SICI and SICF generation. With the use of a multi-channel TMS transducer that provides electronic control of the stimulus orientation and intensity, we aimed to investigate how changes in the CS and TS orientation affect the strength of SICI and SICF. We hypothesized that the CS orientation would play a major role for SICF than for SICI, whereas the CS intensity would be more critical for SICI than for SICF. In eight healthy subjects, we tested two ISIs (1.5 and 2.7 ms), two CS and TS orientations (anteromedial (AM) and posteromedial (PM)), and four CS intensities (50, 70, 90, and 110% of the resting motor threshold (RMT)). The TS intensity was fixed at 110% RMT. The intensities were adjusted to the corresponding RMT in the AM and PM orientations. SICI and SICF were observed in all tested CS and TS orientations. SICI depended on the CS intensity in a U-shaped manner in any combination of the CS and TS orientations. With 70% and 90% RMT CS intensities, stronger PM-oriented CS induced stronger inhibition than weaker AM-oriented CS. Similar SICF was observed for any CS orientation. Neither SICI nor SICF depended on the TS orientation. We demonstrated that SICI and SICF could be elicited by the CS perpendicular to the TS, which indicates that these stimuli affected either overlapping or strongly connected neuronal populations. We concluded that SICI is primarily sensitive to the CS intensity and that CS intensity adjustment resulted in similar SICF for different CS orientations.

Published
2021

40. The impulse noise of TMS inside a 3 T and 9.4 T MRI

Author

Nyrhinen, Mikko, primary, Souza, Victor H., additional, Korhonen, Juuso, additional, Sinisalo, Heikki, additional, Paasonen, Jaakko, additional, Nieminen, Jaakko O., additional, Gröhn, Olli, additional, Ilmoniemi, Risto J., additional, and Lin, Fa-Hsuan, additional

Published
2021
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50. Effect of stimulus orientation and intensity on short-interval intracortical inhibition (SICI) and facilitation (SICF): A multi-channel transcranial magnetic stimulation study

Author

Tugin, Sergei, primary, Souza, Victor H., additional, Nazarova, Maria A., additional, Novikov, Pavel A., additional, Tervo, Aino E., additional, Nieminen, Jaakko O., additional, Lioumis, Pantelis, additional, Ziemann, Ulf, additional, Nikulin, Vadim V., additional, and Ilmoniemi, Risto J., additional

Published
2021
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