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Grafelfing, Germany

Maliia M.D.,Danish Epilepsy Center | Maliia M.D.,Carol Davila University of Medicine and Pharmacy | Meritam P.,Danish Epilepsy Center | Scherg M.,BESA GmbH | And 5 more authors.
Clinical Neurophysiology

Objective: To investigate how often discharge propagation occurs within the spikes recorded in patients evaluated for epilepsy surgery, and to assess its impact on the accuracy of source imaging. Methods: Data were analyzed from 50 consecutive patients who had presurgical workup. Discharge propagation was analyzed using sequential voltage-maps of the averaged spikes, and principal components analysis. When propagation was detected, sources were modeled both at onset and peak. Results: Propagation occurred in half of the patients. The median time of propagation between onset and peak was 17 ms. In 60% of the cases with propagation (15/25 patients) this remained in the same sub-lobar area where onset occurred. The accuracy of source imaging in cases of propagating spikes was 67% when only analyzing onset or peak. This was lower as compared to cases without propagation (79%). Combining source imaging at onset and at peak increased the accuracy to 83% for the propagating spikes. Conclusions: Propagation occurs often in patients with focal epilepsy, evaluated for surgery. In 40% of the propagating cases, the source of onset and peak were in different sub-lobar regions. Significance: For optimal clinical utility, sources should be modeled both at onset and at peak epochs of the spikes. © 2016 International Federation of Clinical Neurophysiology. Source

Rampersad S.M.,Radboud University Nijmegen | Rampersad S.M.,Donders Institute for Brain | Janssen A.M.,Radboud University Nijmegen | Janssen A.M.,Donders Institute for Brain | And 11 more authors.
IEEE Transactions on Neural Systems and Rehabilitation Engineering

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique able to induce long-lasting changes in cortical excitability that can benefit cognitive functioning and clinical treatment. In order to both better understand the mechanisms behind tDCS and possibly improve the technique, finite element models are used to simulate tDCS of the human brain. With the detailed anisotropic head model presented in this study, we provide accurate predictions of tDCS in the human brain for six of the practically most-used setups in clinical and cognitive research, targeting the primary motor cortex, dorsolateral prefrontal cortex, inferior frontal gyrus, occipital cortex, and cerebellum. We present the resulting electric field strengths in the complete brain and introduce new methods to evaluate the effectivity in the target area specifically, where we have analyzed both the strength and direction of the field. For all cerebral targets studied, the currently accepted configurations produced sub-optimal field strengths. The configuration for cerebellum stimulation produced relatively high field strengths in its target area, but it needs higher input currents than cerebral stimulation does. This study suggests that improvements in the effects of transcranial direct current stimulation are achievable. © 2014 IEEE. Source

Janssen A.M.,Radboud University Nijmegen | Rampersad S.M.,Radboud University Nijmegen | Lucka F.,University of Munster | Lanfer B.,University of Munster | And 7 more authors.
Physics in Medicine and Biology

Volume conduction models can help in acquiring knowledge about the distribution of the electric field induced by transcranial magnetic stimulation. One aspect of a detailed model is an accurate description of the cortical surface geometry. Since its estimation is difficult, it is important to know how accurate the geometry has to be represented. Previous studies only looked at the differences caused by neglecting the complete boundary between cerebrospinal fluid (CSF) and grey matter (Thielscher et al 2011 NeuroImage 54 234-43, Bijsterbosch et al 2012 Med. Biol. Eng. Comput. 50 671-81), or by resizing the whole brain (Wagner et al 2008 Exp. Brain Res. 186 539-50). However, due to the high conductive properties of the CSF, it can be expected that alterations in sulcus width can already have a significant effect on the distribution of the electric field. To answer this question, the sulcus width of a highly realistic head model, based on T1-, T2- and diffusion-weighted magnetic resonance images, was altered systematically. This study shows that alterations in the sulcus width do not cause large differences in the majority of the electric field values. However, considerable overestimation of sulcus width produces an overestimation of the calculated field strength, also at locations distant from the target location. © 2013 Institute of Physics and Engineering in Medicine. Source

Agency: Cordis | Branch: H2020 | Program: MSCA-ITN-ETN | Phase: MSCA-ITN-2014-ETN | Award Amount: 3.88M | Year: 2015

The European Brain Council (EBC) has recommended the disorders of the brain to be prioritised for funding. The purpose of this ChildBrain ETN is 1) to train young scientists, Early Stage Researchers (ESRs), to utilise evidence-based neuroscientific knowledge for helping children, especially those at high risk for dropout due to neurocognitive disorders, to meet future educational and societal demands. The network aims 2) to develop new, innovative brain imaging-based tools through research and industry to be applied by researchers and clinical sector end users for 3) increasing understanding and improving diagnosis and treatment of neurocognitive disorders, as well as enhancing targeted educational programs. To accomplish these goals, we aim 4) to form a cross-disciplinary and trans-sectorial European network of experts. Three research and two training work packages (WPs) are planned to reach these goals. The Childhood neurodevelopmental disorders WP comprises new research and training on the neural underpinnings of dyslexia, ADHD, epilepsy, and hearing loss and creates links to healthcare industry and special education. The Brain development WP will focus on understanding the systems-level brain development at the level of the individual child. The Brain research methods WP will develop new multi-modal data analysis methodologies that are essential for children and will also further brain research in adults. The academic, industrial and private sector partners will work across these themes, offering the ESRs project-specific collaboration, secondments, workshops, summer school and courses on scientific, transferable and entrepreneurial skills, as well as supervision. The ChildBrain ETN will produce a new generation of scientists with the theoretical, technological, and entrepreneurial skills necessary for making breakthroughs in the understanding of brain development and childhood neurocognitive disorders.

BESA GmbH and Megis Software Gmbh | Date: 2008-04-29

computer programs and data processors for analyzing and processing electroencephalographic and magnetoencephalographic data.

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