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Research Interests: Neuroscience, Psychology, Magnetic Resonance Imaging, Adolescent, Medicine, and 15 moreVisual Cortex, Brain Mapping, Vision, Brain, Humans, Child, Cerebral Cortex, Hemispheric Asymmetry, Adult, Postnatal development, Left Hemisphere, Age Groups, Striate Cortex, Psychology and Cognitive Sciences, and Medical and Health Sciences
Research Interests: Magnetoencephalography, Magnetic Resonance Imaging, Epilepsy, Electroencephalography, Adolescent, and 15 moreMedicine, Brain Mapping, Humans, Child, Cluster Analysis, Epilepsia, Clinical Sciences, Middle Aged, Ictal, Adult, Medicine and Health Sciences, Neurosciences, Frontal Lobe, Frontal Lobe Epilepsy, and mass Screening
Controversy remains regarding the preferred modality, magnetoencephalography (MEG) or EEG, for the presurgical evaluation of patients with epilepsy. In general, it appears that the spike yields for MEG and EEG are similar in patients with... more
Controversy remains regarding the preferred modality, magnetoencephalography (MEG) or EEG, for the presurgical evaluation of patients with epilepsy. In general, it appears that the spike yields for MEG and EEG are similar in patients with temporal lobe epilepsy, and that for neocortical epilepsy the MEG spike yields may be larger than for EEG. In general, MEG/EEG spike yields depend on factors such as (1) the number of sensors, (2) the source depth and orientation, (3) the background activity, and (4) the smearing of the potential fields due to variations in skull resistivity in EEG. Because the contribution of all these factors are of the same order of magnitude, the authors took them all into account to predict the signal-to-noise ratio (SNR) of hypothetical spikes in different brain areas. In this study, it was assumed that spike sensitivity (and therefore the spike yield) increases with SNR. The estimated SNR values at temporal areas were comparable for MEG and EEG, which is in agreement with clinical findings that spike yields in temporal lobe epilepsy are similar. Furthermore, the SNR of MEG was substantially higher in the frontal area, indicating that in frontal lobe epilepsy MEG may be highly relevant to prescreening of epilepsy patients. This model-based approach indicates that SNR mapping clarifies differences between MEG and EEG findings that are difficult to understand on the basis of patient studies only.
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Research Interests: Psychology, Radiology, Magnetoencephalography, Magnetic Resonance Imaging, Epilepsy, and 15 moreLocalization, Medicine, MEG, Classification, Diagnostics, Clinical Sciences, Concordance, Ictal, Intractable Epilepsy, Lesion, Medicine and Health Sciences, Abnormality, Neurosciences, Focal Cortical Dysplasia, and Focal epilepsy
Co-registered EEG and functional MRI (EEG/fMRI) is a potential clinical tool for planning invasive EEG in patients with epilepsy. In addition, the analysis of EEG/fMRI data provides a fundamental insight into the precise physiological... more
Co-registered EEG and functional MRI (EEG/fMRI) is a potential clinical tool for planning invasive EEG in patients with epilepsy. In addition, the analysis of EEG/fMRI data provides a fundamental insight into the precise physiological meaning of both fMRI and EEG data. Routine application of EEG/fMRI for localization of epileptic sources is hampered by large artefacts in the EEG, caused by switching of scanner gradients and heartbeat effects. Residuals of the ballistocardiogram (BCG) artefacts are similarly shaped as epileptic spikes, and may therefore cause false identification of spikes. In this study, new ideas and methods are presented to remove gradient artefacts and to reduce BCG artefacts of different shapes that mutually overlap in time. Gradient artefacts can be removed efficiently by subtracting an average artefact template when the EEG sampling frequency and EEG low-pass filtering are sufficient in relation to MR gradient switching (Gonçalves et al., 2007). When this is not the case, the gradient artefacts repeat themselves at time intervals that depend on the remainder between the fMRI repetition time and the closest multiple of the EEG acquisition time. These repetitions are deterministic, but difficult to predict due to the limited precision by which these timings are known. Therefore, we propose to estimate gradient artefact repetitions using a clustering algorithm, combined with selective averaging. Clustering of the gradient artefacts yields cleaner EEG for data recorded during scanning of a 3T scanner when using a sampling frequency of 2048 Hz. It even gives clean EEG when the EEG is sampled with only 256 Hz. Current BCG artefacts-reduction algorithms based on average template subtraction have the intrinsic limitation that they fail to deal properly with artefacts that overlap in time. To eliminate this constraint, the precise timings of artefact overlaps were modelled and represented in a sparse matrix. Next, the artefacts were disentangled with a least squares procedure. The relevance of this approach is illustrated by determining the BCG artefacts in a data set consisting of 29 healthy subjects recorded in a 1.5 T scanner and 15 patients with epilepsy recorded in a 3 T scanner. Analysis of the relationship between artefact amplitude, duration and heartbeat interval shows that in 22% (1.5T data) to 30% (3T data) of the cases BCG artefacts show an overlap. The BCG artefacts of the EEG/fMRI data recorded on the 1.5T scanner show a small negative correlation between HBI and BCG amplitude. In conclusion, the proposed methodology provides a substantial improvement of the quality of the EEG signal without excessive computer power or additional hardware than standard EEG-compatible equipment.
Research Interests: Computer Science, Algorithms, Artificial Intelligence, Magnetic Resonance Imaging, Electroencephalography, and 14 moreMedicine, Brain Mapping, Humans, Clustering, Neuroimage, EEG/FMRI, Scanner, Artifacts, Image Enhancement, Reproducibility of Results, Sensitivity and Specificity, Psychology and Cognitive Sciences, Subtraction, and Medical and Health Sciences
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De standaard klinische beoordeling van het EEG gemeten met diepte-elektroden richt zich voornamelijk op aanvalsactiviteit. Dit EEG bevat echter veelvuldig interictale epileptiforme ontladingen, die gekenmerkt worden door een complex... more
De standaard klinische beoordeling van het EEG gemeten met diepte-elektroden richt zich voornamelijk op aanvalsactiviteit. Dit EEG bevat echter veelvuldig interictale epileptiforme ontladingen, die gekenmerkt worden door een complex spatiotemporeel patroon. In deze bijdrage wordt een kwantitatieve analyse gepresenteerd die dergelijke complexe ontladingen groepeert en lokaliseert1 . Dit blijkt extra informatie te bieden die bepalend kan zijn voor de operatiestrategie.
Research Interests: Psychology and Humanities
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MEG and EEG after sleep deprivation (EEG‐SD) are applied as diagnostic tools in the evaluation of patients with possible epilepsy. There is no gold standard to check whether the diagnosis based on these two modalities is correct. The best... more
MEG and EEG after sleep deprivation (EEG‐SD) are applied as diagnostic tools in the evaluation of patients with possible epilepsy. There is no gold standard to check whether the diagnosis based on these two modalities is correct. The best standard available is the long‐term follow‐up of patients. As follow‐up of an earlier study in which the additional value of MEG vs EEG‐SD diagnosis was evaluated, we investigated the long‐term validity of MEG‐based and EEG‐SD‐based diagnosis.
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At present, in epilepsy, magnetoencephalography (MEG) is mostly used for presurgical evaluations. It has proven to be robust for detecting and localizing interictal epileptiform discharges. Whether this is also true for first-line... more
At present, in epilepsy, magnetoencephalography (MEG) is mostly used for presurgical evaluations. It has proven to be robust for detecting and localizing interictal epileptiform discharges. Whether this is also true for first-line investigation in the diagnosis of epilepsy has not been investigated yet. We present our data on the usefulness of MEG in the earliest phase of diagnosing epilepsy. We examined 51 patients with suspicion of neocortical epilepsy and an inconclusive routine EEG. A method to integrate MEG in daily routine was developed. Results of visually assessed MEG recordings were compared, retrospectively, with clinical data and with the results of EEG after sleep deprivation. After a finding of inconclusive, routine MEG generated a gain in diagnostic value of 63% when compared with "final" clinical diagnosis. This is comparable with the added value of EEG after sleep deprivation recorded previously in the same patients. However, MEG is less of a burden for patient and hospital and has no association with risk of increase in seizure frequency. The routine MEG with visual assessment only is a reliable diagnostic tool in the routine diagnosis of epilepsy and may replace or precede EEG after sleep deprivation in daily clinical practice. Furthermore, MEG together with MRI enables magnetic source imaging and, thus, may provide additional information on the cortical localization of the epilepsy of a patient.
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Research Interests: Humanities and Art
The checkerboard onset Evoked Potential (EP) does not obtain its adult form before puberty. To determine the site of origin of these processes we studied the origin of the checkerboard onset EP in a group of 10 children between the ages... more
The checkerboard onset Evoked Potential (EP) does not obtain its adult form before puberty. To determine the site of origin of these processes we studied the origin of the checkerboard onset EP in a group of 10 children between the ages of 6 and 16 years. Since the development of the waveform of the pattern onset EP varies with check size we also studied the dependence of these EPs on check size. The child checkerboard onset EPs described in this paper are dominated by a single source. Following an equivalent dipole source localization approach, the position, orientation and variation in strength of the equivalent dipole is estimated. The position and orientation of this dipole indicates an origin in the primary visual cortex (area 17). The variation in strength of the dipole changes from a single positive deflection, specific for children of 8 years and younger, into a negative-positive complex for the children studied between the age of 9 and 16 years. These changes in waveform must be due to changes in the activity pattern of the striate cortex.
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Research Interests: Cognitive Science, Magnetic Resonance Imaging, Epilepsy, Functional MRI, Electroencephalography, and 15 moreMedicine, Linear models, Brain Mapping, Brain, Evoked Potentials, Humans, Heart rate, Artifacts, Adult, Human Brain Mapping, Medicine and Health Sciences, Neurosciences, Alpha Rhythm, Hemoglobins, and Impulse Response Function
Research Interests: Cognitive Science, Computer Science, Algorithms, Biomedical Engineering, Design Theory, and 15 moreEpilepsy, Electroencephalography, Brain Mapping, Brain, Humans, Hemodynamics, Functional Magnetic Resonance Imaging, Heart rate, Clinical Sciences, Electrodes, Causal Effect, Alpha Rhythm, Hemodynamic Response Function, BOLD response, and Focal epilepsy
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No physiological correlates are known for visual fatigue produced by prolonged viewing of visual display terminals (VDTs). The primary aim of the present study was to find a physiological correlate of a performance measure which is... more
No physiological correlates are known for visual fatigue produced by prolonged viewing of visual display terminals (VDTs). The primary aim of the present study was to find a physiological correlate of a performance measure which is related to fatigue. The assumption was that a change in the state of fatigue expresses itself in fluctuations of accommodation. If indeed variations in
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Research Interests: Computer Science, Algorithms, Artificial Intelligence, Computer Vision, Biomedical Engineering, and 15 moreQuality, Magnetic Resonance Imaging, Epilepsy, Electroencephalography, Medicine, Humans, Scanner, Artifacts, Reduction, Motion, Recordings, Medicine and Health Sciences, MR Scanner, Electrical And Electronic Engineering, and Subtraction
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Research Interests: Neuroscience, Mathematics, Applied Mathematics, Computer Science, Image Processing, and 15 moreNeuroanatomy, Neuroimaging, Epilepsy, Medical Physics, Medicine, Multidisciplinary, Diffusion MRI, Biological Sciences, Anatomy, Humans, Diffusion, Contextual, Nervous System, Epilepsy Surgery, and Diffusion magnetic resonance imaging
Research Interests: Engineering, Magnetoencephalography, Magnetic Resonance Imaging, Epilepsy, Adolescent, and 15 moreMagnetic field, Brain Mapping, Humans, Child, Female, Clinical, Male, Clinical Neurophysiology, Adult, Lesion, Epilepsy Surgery, Frontal Lobe, Magnetic resonance image, Frontal Lobe Epilepsy, and Electric stimulation
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Adresses e-mail : sadeghiye hashem@yahoo.com, sadeghiye@ut.ac.it (H. Sadeghiyeh) The present study aimed to examine the gender differences in empathy for pain at a sensorimotor level. Previous studies using single-pulse TMS have shown a... more
Adresses e-mail : sadeghiye hashem@yahoo.com, sadeghiye@ut.ac.it (H. Sadeghiyeh) The present study aimed to examine the gender differences in empathy for pain at a sensorimotor level. Previous studies using single-pulse TMS have shown a reduction in amplitude of motor-evoked potentials (MEPs) while subjects observing needles penetrating hand of a human model which was specific to the muscle subjects observed being pricked. Twenty-five subjects (thirteen females and twelve males) participated in the study. Their TMS-induced MEPs were recorded from their right first dorsal interosseus (FDI) muscle of index finger during watching various clips depicting needles penetrating the same FDI muscle of right hand of a model. There were twelve types of clips, including pictures of hands of a woman, a man, a child and an apple, which was either pinpricked by a needle, touched by a Q-tip or at rest. Each clip was shown to the subjects eighteen times in a completely random sequence. Electromyography signals were recorded through an amplifier of an ANT ERP recording system and analysed by ASA-Lab software. Results had been shown that women had larger MEP inhibited amplitude than men in all the stimuli. However, there were no significant differences between MEP amplitudes of different types of models’ hands. The gender differences of MEPs between subjects indicate greater sensorimotor empathy in women, which is in correspondence with greater subjective responses of women to the painful clips (state empathy), which were obtained through a Visual Analogue Scale. Therefore, upon these results, we can conclude that women’s stronger empathic response to observing pain in others go beyond just a subjective level and extend to a very automatic and sensorimotor level. Women are hard-wired to embody the pain of others more intensely, and this could prepare them to take action towards others’ pain more rapidly. Further reading
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Research Interests: Engineering, Neuroscience, Psychology, Neurology, Magnetoencephalography, and 13 moreEpilepsy, Electroencephalography, Medicine, Journal Article, Clinical Neurology, Medical Physiology, Clinical Neurophysiology, Ictal, Sensory Systems, Treatment Response, Childhood Absence Epilepsy, Psychology and Cognitive Sciences, and Medical and Health Sciences
Poster: "ECR 2012 / C-0755 / Diffusion Weighted Imaging Guided Surgical Applications" by: "E. Brunenberg1, V. Visser-Vandewalle2, C. Tax1, P. Ossenblok3, R. Duits1, E. van Aart1, B. M. ter Haar Romeny1, A. Vilanova1;... more
Poster: "ECR 2012 / C-0755 / Diffusion Weighted Imaging Guided Surgical Applications" by: "E. Brunenberg1, V. Visser-Vandewalle2, C. Tax1, P. Ossenblok3, R. Duits1, E. van Aart1, B. M. ter Haar Romeny1, A. Vilanova1; 1Eindhoven/NL, 2Maastricht, Limburg/NL, 3Heeze, Noord Brabant/NL"
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Aim. The diagnostic process for epilepsy can be lengthy and stressful, which may delay the start of treatment. The objective of this study was to determine the benefit of routine magnetoencephalography (MEG) with regard to diagnostic... more
Aim. The diagnostic process for epilepsy can be lengthy and stressful, which may delay the start of treatment. The objective of this study was to determine the benefit of routine magnetoencephalography (MEG) with regard to diagnostic gain, compared to routine electroencephalography (EEG), EEG following sleep deprivation (EEGsd), and 24‐hour EEG.Methods. In this prospective study, patients were included from two centres (Academic Centre for Epileptology Kempenhaeghe, Heeze and Elisabeth‐Twee Steden Hospital, Tilburg) and MEG recording took place at a single centre (Amsterdam University Medical Centre, Vrije Universiteit Amsterdam) in The Netherlands. Consecutively referred patients from peripheral hospitals were included between August 2013 and March 2016. Patients were offered routine MEG in addition to EEG examination and MRI for the diagnosis of epilepsy. The final clinical diagnosis was based on all available clinical data and test results at the end of the diagnostic process. Se...
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This chapter describes the hemodynamic response function (HRF) estimation problem in detail, and discusses its underlying assumptions. Different variants of the method are applied using the data of a single subject that was chosen for... more
This chapter describes the hemodynamic response function (HRF) estimation problem in detail, and discusses its underlying assumptions. Different variants of the method are applied using the data of a single subject that was chosen for illustrative purposes.