Event-related potentials reveal preserved attention allocation but impaired emotion regulation in patients with epilepsy and comorbid negative affect

Patients with epilepsy have a high prevalence of comorbid mood disorders. This study aims to evaluate whether negative affect in epilepsy is associated with dysfunction of emotion regulation. Event-related potentials (ERPs) are used in order to unravel the exact electrophysiological time course and investigate whether a possible dysfunction arises during early (attention) and/or late (regulation) stages of emotion control. Fifty epileptic patients with (n = 25) versus without (n = 25) comorbid negative affect plus twenty-five matched controls were recruited. ERPs were recorded while subjects performed a face- or house-matching task in which fearful, sad or neutral faces were presented either at attended or unattended spatial locations. Two ERP components were analyzed: the early vertex positive potential (VPP) which is normally enhanced for faces, and the late positive potential (LPP) that is typically larger for emotional stimuli. All participants had larger amplitude of the early face-sensitive VPP for attended faces compared to houses, regardless of their emotional content. By contrast, in patients with negative affect only, the amplitude of the LPP was significantly increased for unattended negative emotional expressions. These VPP results indicate that epilepsy with or without negative affect does not interfere with the early structural encoding and attention selection of faces. However, the LPP results suggest abnormal regulation processes during the processing of unattended emotional faces in patients with epilepsy and comorbid negative affect. In conclusion, this ERP study reveals that early object-based attention processes are not compromised by epilepsy, but instead, when combined with negative affect, this neurological disease is associated with dysfunction during the later stages of emotion regulation. As such, these new neurophysiological findings shed light on the complex interplay of epilepsy with negative affect during the processing of emotional visual stimuli and in turn might help to better understand the etiology and maintenance of mood disorders in epilepsy

Source reconstruction of the P300 event-related potential as a biomarker for the efficacy of vagus nerve stimulation in patients with epilepsy

Abstract The working mechanism of VNS remains to be fully understood, making it impossible to predict a patient’s response to the treatment. In the present study, we explore whether EEG source reconstruction of the P300 event-related potential can provide information about the working mechanism and efficacy of VNS. 1. Introduction Vagus Nerve Stimulation (VNS) is a neurostimulation treatment for refractory epilepsy that reduces seizures with more than 50% in one third of the treated patients. The working mechanism of VNS is currently unknown. This makes it impossible to predict whether a patient will benefit from VNS treatment or not prior to implantation. Therefore, we want to further investigate the working mechanism of VNS and find biomarkers that indicate the efficacy of the treatment. 2. Data and methods In this study, the P300 component of the event-related potential during the auditory oddball task was investigated in VNS responders (R) and non-responders (NR) under two conditions: VNS turned ON vs. OFF. The P300 component is modulated by the norepinephrine level in the brain, which has been linked to the anti-epileptic effect of VNS [1]. 60-channel EEG was recorded in 10R and 10NR of VNS. The sources of the P300 wave were reconstructed using the multiple volumetric sparse priors algorithm [2]. For 14 patients (6R + 8NR), individual head models including scalp, skull, cerebrospinal fluid, gray and white matter, were constructed as a good quality MR image was available. For the other 6 patients, a template head model, including scalp, skull, CSF and brain, was used. Second level analysis was performed in the statistical parametric mapping software to find significant differences between the R and NR. 3. Results Significant differences in brain activity for R vs. NR were found in the left hippocampus, fusiform gyrus and insular lobe (pcorr<0.001), indicating a possible biomarker for the efficacy of VNS. Significant differences in brain activity were found for VNS OFF vs. ON in the left and right hippocampus and amygdala (p¬uncorr<0.02), indicating that the lymbic system is involved in the mechanism of action of VNS. If we look at the difference between VNS OFF and ON in each group separately, there is an indication that the right hippocampus is more influenced by VNS in R than in NR, while the opposite holds for the left middle orbital gyrus. However, no significance was reached. 4. Conclusion Although more research is needed, we showed the potential of EEG source reconstruction as a means to provide information on the working mechanism of VNS and as a biomarker for the efficacy of VNS. References [1] Raedt, R. et al. Increased hippocampal noradrenaline is a biomarker for efficacy of vagus nerve stimulation in a limbic seizure model. Journal of neurochemistry, 117(3), 461-469, 2011. [2] Strobbe, G. et al. Multiple sparse volumetric priors for distributed EEG source reconstruction. NeuroImage, 100, 715-724, 2014

EPTRI Belgian Joint Research Unit : harmonisation and concertation of paediatric research in Belgium to ensure better and safer healthcare for children

We want to put the excellent translational paediatric research in Belgium on the ESFRI national roadmap in order to participate in the European Paediatric Translational Research Infrastructure (EPTRI) project. Therefore, we are in the preparatory phase to form a Belgian national EPTRI Joint Research Unit (JRU). Academic research organisations and hospitals from both regions, Flanders and Wallonia are currently involved. The Belgian JRU partners will gather complementary scientific and technological competencies in the different EPTRI thematic research platforms: 1. Paediatric medicines discovery: with different types of “in vitro” paediatric models, placental and umbilical cord and 3D organoid cell cultures from paediatric samples and juvenile animal models such as the rabbit BPD model, juvenile Göttingen minipig, juvenile conventional pig model and developmental zebrafish model; 2. Paediatric biomarkers and biosamples: identification, characterisation and validation of the biomarkers used as prognostic tools, safety markers and diagnostic tools in paediatric diseases; 3. Developmental pharmacology: including PK (bioavaibility/bioequivalence) studies, Population PKPD analysis and PK/PD modelling; 4. Paediatric medicines formulations and medical devices: including regulatory knowledge of paediatric medical devices. The partners will ensure a strong liaison with other RI’s such as the BBMRI-ERIC for paediatric biobanking and the IMI conect4children network paediatric clinical trials. We propose an integrated paediatric research system that links together EPTRI Belgium with landmark RIs, conect4children and the many paediatric clinical research networks and institutions that provide services to paediatric research. This integrated system can provide: expertise, experienced facilities and practical support for pre-clinical and clinical paediatric research in Belgium and Europe. Sharing understanding of patients’ needs and concerted efforts in paediatric research will further enhance the health of children

Decoding steady-state visual evoked potentials from electrocorticography

We report on a unique electrocorticography (ECoG) experiment in which Steady-State Visual Evoked Potentials (SSVEPs) to frequency-and phase-tagged stimuli were recorded from a large subdural grid covering the entire right occipital cortex of a human subject. The paradigm is popular in EEG-based Brain Computer Interfacing where selectable targets are encoded by different frequency-and/or phase-tagged stimuli. We compare the performance of two state-of-the-art SSVEP decoders on both ECoG-and scalp-recorded EEG signals, and show that ECoG-based decoding is more accurate for very short stimulation lengths (i.e., less than 1 s). Furthermore, whereas the accuracy of scalp-EEG decoding bene fi ts from a multi-electrode approach, to address interfering EEG responses and noise, ECoG decoding enjoys only a marginal improvement as even a single electrode, placed over the posterior part of the primary visual cortex, seems to suf fi ce. This study shows, for the fi rst time, that EEG-based SSVEP decoders can in principle be applied to ECoG, and can be expected to yield faster decoding speeds using less electrodes

The European Paediatric Clinical Trials Network conect4children : activities of the Belgium National Network and its progression

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