Victor H. Souza

Aalto University

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Risto J. Ilmoniemi

Aalto University

Jaakko O. Nieminen

Aalto University

Oswaldo Baffa

Universidade de Ribeirão Preto

Renan H. Matsuda

Aalto University

Pantelis Lioumis

Aalto University

Heikki Sinisalo

Aalto University

Marco Antônio Cavalcanti Garcia

Universidade Federal de Juiz de Fora

Juuso T. Korhonen

Helsinki University Hospital

Olli‐Pekka Kahilakoski

Aalto University

Aino E. Tervo

Aalto University

Cooperative Institutions

Aalto University

Universidade de São Paulo

University of Helsinki

Stanford University

Universidade Federal do Rio de Janeiro

Universidade de Ribeirão Preto

Helsinki University Hospital

University of Tübingen

Universidade Federal de Juiz de Fora

Hertie Institute for Clinical Brain Research

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

ASSOCIATION OF POLYMORPHISM IN TICAM1 GENE WITH PROTECTION TO MODERATE/SEVERE COVID-19

Arquivos do Mudi (2023)

Matheus Braga Pedro E. Santiago Silva Aléia Harumi Uchibaba Yamanaka Victor H. Souza Sérgio Grava

Clinical outcomes of Covid-19 have shown variability between individuals and populations. TICAM1 gene encodes the TRIFF protein, essential in the antiviral response, then the purpose of the study was to assess the effect of the polymorphism (rs2292151) G>A of TICAM1 gene on the severity of COVID-19 in individuals from the northern region of Paraná. A case-control study was performed, including patients, 100 mild and 50 moderate/severe Covid-19 cases, classified according to the WHO, by Hospital Paraná, Maringá, Brazil. The exclusion criteria used were: patients with heart disease, liver disease, other respiratory diseases, HIV, and cancer.The (rs2292151) G>A polymorphism was genotyped by qPCR and statistical analysis was performed using logistic regression in the SNPStats software. The genotype distribution was according to the expected in the Hardy-Weinberg equilibrium. There was an associationbetween the A/A genotype in a codominant model with protection against the severity of the disease (OR=0.14, 95% CI 0.03.-0.75, P = 0.01). The frequency of genotype A/A was 12% in mild cases and 4% in serious cases; the G/A was 44% in mild cases and 30% in serious cases, and the G/G was 44% in mild cases and 66% in serious cases. We can conclude that the A/A genotype (in a codominant genetic model) of the polymorphism (rs2292151) G>A was associated with a protection factor for moderate/severe Covid-19 in this population, however,the genotype determination should be done in a high number of patients.

Gene polymorphism

10.4025/arqmudi.v27iespecial.68168

Cite

Citations (0)

Targeting multi-locus TMS with Bayesian optimization

Brain stimulation (2025)

Ida Granö Olli‐Pekka Kahilakoski Miriam Kirchhoff Oskari Ahola Giulia Pieramico

Bayesian Optimization

10.1016/j.brs.2024.12.250

Cite

Citations (0)

P78 Multi-locus TMS system for electronically controlled stimulation within a cortical region

Clinical Neurophysiology (2020)

Jaakko O. Nieminen Mikko Malmi Diego Milardovich Heikki Sinisalo Victor H. Souza

10.1016/j.clinph.2019.12.189

Cite

Citations (0)

Patient-specific neurosurgical phantom: assessment of visual quality, accuracy, and scaling effects

3D Printing in Medicine (2018)

Felipe Wilker Grillo Victor H. Souza Renan H. Matsuda Carlo Rondinoni Theo Z. Pavan

Training in medical education depends on the availability of standardized materials that can reliably mimic the human anatomy and physiology. One alternative to using cadavers or animal bodies is to employ phantoms or mimicking devices. Styrene-ethylene/butylene-styrene (SEBS) gels are biologically inert and present tunable properties, including mechanical properties that resemble the soft tissue. Therefore, SEBS is an alternative to develop a patient-specific phantom, that provides real visual and morphological experience during simulation-based neurosurgical training.A 3D model was reconstructed and printed based on patient-specific magnetic resonance images. The fused deposition of polyactic acid (PLA) filament and selective laser sintering of polyamid were used for 3D printing. Silicone and SEBS materials were employed to mimic soft tissues. A neuronavigation protocol was performed on the 3D-printed models scaled to three different sizes, 100%, 50%, and 25% of the original dimensions. A neurosurgery team (17 individuals) evaluated the phantom realism as "very good" and "perfect" in 49% and 31% of the cases, respectively, and rated phantom utility as "very good" and "perfect" in 61% and 32% of the cases, respectively. Models in original size (100%) and scaled to 50% provided a quantitative and realistic visual analysis of the patient's cortical anatomy without distortion. However, reduction to one quarter of the original size (25%) hindered visualization of surface details and identification of anatomical landmarks.A patient-specific phantom was developed with anatomically and spatially accurate shapes, that can be used as an alternative for surgical planning. Printed models scaled to sizes that avoided quality loss might save time and reduce medical training costs.

10.1186/s41205-018-0025-8

Cite

Citations (36)

P42 Towards concurrent multi-locus TMS and functional MRI in rats

Clinical Neurophysiology (2020)

Victor H. Souza Juuso T. Korhonen Jaakko Paasonen Jaakko O. Nieminen Hanne Laakso

10.1016/j.clinph.2019.12.153

Cite

Citations (0)

Multi-locus transcranial magnetic stimulation system for electronically targeted brain stimulation

Brain stimulation (2021)

Jaakko O. Nieminen Heikki Sinisalo Victor H. Souza Mikko Malmi Mikhail Yuryev

BackgroundTranscranial magnetic stimulation (TMS) allows non-invasive stimulation of the cortex. In multi-locus TMS (mTMS), the stimulating electric field (E-field) is controlled electronically without coil movement by adjusting currents in the coils of a transducer.ObjectiveTo develop an mTMS system that allows adjusting the location and orientation of the E-field maximum within a cortical region.MethodsWe designed and manufactured a planar 5-coil mTMS transducer to allow controlling the maximum of the induced E-field within a cortical region approximately 30 mm in diameter. We developed electronics with a design consisting of independently controlled H-bridge circuits to drive up to six TMS coils. To control the hardware, we programmed software that runs on a field-programmable gate array and a computer. To induce the desired E-field in the cortex, we developed an optimization method to calculate the currents needed in the coils. We characterized the mTMS system and conducted a proof-of-concept motor-mapping experiment on a healthy volunteer. In the motor mapping, we kept the transducer placement fixed while electronically shifting the E-field maximum on the precentral gyrus and measuring electromyography from the contralateral hand.ResultsThe transducer consists of an oval coil, two figure-of-eight coils, and two four-leaf-clover coils stacked on top of each other. The technical characterization indicated that the mTMS system performs as designed. The measured motor evoked potential amplitudes varied consistently as a function of the location of the E-field maximum.ConclusionThe developed mTMS system enables electronically targeted brain stimulation within a cortical region.

Brain stimulation

10.1016/j.brs.2021.11.014

Cite

Citations (50)

Directional sensitivity of cortical neurons towards TMS-induced electric fields

Imaging Neuroscience (2023)

Konstantin Weise Torge Worbs Benjamin Kalloch Victor H. Souza Aurélien T. Jaquier

Abstract We derived computationally efficient average response models of different types of cortical neurons, which are subject to external electric fields from Transcranial Magnetic Stimulation. We used 24 reconstructions of pyramidal cells (PC) from layer 2/3, 245 small, nested, and large basket cells from layer 4, and 30 PC from layer 5 with different morphologies for deriving average models. With these models, it is possible to efficiently estimate the stimulation thresholds depending on the underlying electric field distribution in the brain, without having to implement and compute complex neuron compartment models. The stimulation thresholds were determined by exposing the neurons to TMS-induced electric fields with different angles, intensities, pulse waveforms, and field decays along the somato-dendritic axis. The derived average response models were verified by reference simulations using a high-resolution realistic head model containing several million neurons. The relative errors of the estimated thresholds between the average model and the reference model ranged between -3% and 3.7% in 98% of the cases, while the computation time was only a fraction of a second compared to several weeks. Finally, we compared the model behavior to TMS experiments and observed high correspondence to the orientation sensitivity of motor evoked potentials. The derived models were compared to the classical cortical column cosine model and to simplified ball-and-stick neurons. It was shown that both models oversimplify the complex interplay between the electric field and the neurons and do not adequately represent the directional sensitivity of the different cell types. The derived models are simple to apply and only require the TMS-induced electric field in the brain as input variable. The models and code are available to the general public in open-source repositories for integration into TMS studies to estimate the expected stimulation thresholds for an improved dosing and treatment planning in the future.

10.1162/imag_a_00036

Cite

Citations (11)

Real-time tractography-assisted neuronavigation for TMS

bioRxiv (Cold Spring Harbor Laboratory) (2023)

Dogu Baran Aydogan Victor H. Souza Renan H. Matsuda Pantelis Lioumis Risto J. Ilmoniemi

Abstract Background State-of-the-art navigated transcranial magnetic stimulation (nTMS) systems can display the TMS coil position relative to the structural magnetic resonance image (MRI) of the subject’s brain and calculate the induced electric field. However, the local effect of TMS propagates via the white-matter network to different areas of the brain, and currently there is no commercial or research neuronavigation system that can highlight in real time the brain’s structural connections during TMS. Objective To develop a real-time tractography-assisted TMS neuronavigation system and investigate its feasibility. Method We propose a modular framework that seamlessly integrates offline (preparatory) analysis of diffusion MRI data with online (real-time) tractography. For tractography and neuronavigation we combine our custom software Trekker and InVesalius, respectively. We evaluate the feasibility of our system by comparing online and offline tractography results in terms of streamline count and their overlap. Results A real-time tractography-assisted TMS neuronavigation system is developed. Key features include the application of state-of-the-art tractography practices, the ability to tune tractography parameters on the fly, and the display of thousands of new streamlines every few seconds using a novel uncertainty visualization technique. We demonstrate in a video the feasibility and quantitatively show the agreement with offline filtered streamlines. Conclusion Real-time tractography-assisted TMS neuronavigation is feasible. With our system, it is possible to target specific brain regions based on their structural connectivity, and to aim for the fiber tracts that make up the brain’s networks.

Neuronavigation

10.1101/2023.03.09.531565

Cite

Citations (4)

TMS with fast and accurate electronic control: measuring the orientation sensitivity of corticomotor pathways

bioRxiv (Cold Spring Harbor Laboratory) (2021)

Victor H. Souza Jaakko O. Nieminen Sergei Tugin Lari M. Koponen Oswaldo Baffa

Abstract Background Transcranial magnetic stimulation (TMS) coils allow only a slow, mechanical adjustment of the stimulating electric field (E-field) orientation in the cerebral tissue. Fast E-field control is needed to synchronize the stimulation with the ongoing brain activity. Also, empirical models that fully describe the relationship between evoked responses and the stimulus orientation and intensity are still missing. Objective We aimed to (1) develop a TMS transducer for manipulating the E-field orientation electronically with high accuracy at the neuronally meaningful millisecond-level time scale and (2) devise and validate a physiologically based model describing the orientation selectivity of neuronal excitability. Methods We designed and manufactured a two-coil TMS transducer. The coil windings were computed with a minimum-energy optimization procedure, and the transducer was controlled with our custom-made electronics. The electronic E-field control was verified with a TMS characterizer. The motor evoked potential amplitude and latency of a hand muscle were mapped in 3° steps of the stimulus orientation in 16 healthy subjects for three stimulation intensities. We fitted a logistic model to the motor response amplitude. Results The two-coil TMS transducer allows one to manipulate the pulse orientation accurately without manual coil movement. The motor response amplitude followed a logistic function of the stimulus orientation; this dependency was strongly affected by the stimulus intensity. Conclusion The developed electronic control of the E-field orientation allows exploring new stimulation paradigms and probing neuronal mechanisms. The presented model helps to disentangle the neuronal mechanisms of brain function and guide future non-invasive stimulation protocols.

Stimulus (psychology)

10.1101/2021.08.20.457096

Cite

Citations (8)

Software architecture for closed-loop multi-locus transcranial magnetic stimulation

Brain stimulation (2021)

Olli‐Pekka Kahilakoski Juuso T. Korhonen Victor H. Souza Roberto Guidotti Dogu Baran Aydogan

Brain stimulation

10.1016/j.brs.2021.10.190

Cite

Citations (1)