Detection precoce de crisesd’epilepsie a l’aide d’unemodelisation du comportementoscillatoire neu... more Detection precoce de crisesd’epilepsie a l’aide d’unemodelisation du comportementoscillatoire neuronal
To report an innovative spike detection algorithm that tailors its detection to the patient. Inte... more To report an innovative spike detection algorithm that tailors its detection to the patient. Interictal epileptiform activity quantification was accomplished in the setting of epileptic syndromes with continuous spike and waves during slow sleep, which is a time-consuming task for the EEG analysis. The algorithm works in three steps. Firstly, a first spike detection is made with generic parameters. Secondly, the detected spikes are used to tailor the detection algorithm to the patient; and thirdly, the resulting patient-specific detection algorithm is used to analyze individual patient with high-quality detection. Therefore, the algorithm produces a patient-specific template -hence exhibiting improved performance metrics, without the need of a priori knowledge from the experts. The system was first evaluated for EEG of three patients, against the scoring of three EEG experts, demonstrating similar performance. Later, it was evaluated against the spike and wave percentage evaluation of another expert for 17 additional records. The difference between the two evaluations was 4.4% on average, which is almost the same as the interexpert difference (4.7%). We designed a fully automated and efficient spike detection algorithm, which is liable to trim down the specialist's diagnostic time.
We propose an approach that combines a neural mass model and clinical intracranial electroencepha... more We propose an approach that combines a neural mass model and clinical intracranial electroencephalographic (iEEG) recordings to explore the potential pathophysiological mechanisms (at the neuronal population level) of ictogenesis. Thirty iEEG recordings from 10 temporal lobe epilepsy (TLE) patients around seizure onset were investigated. Physiologically meaningful parameters [average excitatory (Ae), slow (B), and fast (G) inhibitory synaptic gain] were identified during interictal to ictal transition. Four ratios (Ae/G, Ae/B, Ae/(B + G), and B/G) were derived from these parameters, and their evolution over time was analyzed. The excitation/inhibition ratio increased around seizure onset and decreased before seizure offset, indicating the impairment and re‐emergence of excitation/inhibition balance around seizure onset and before seizure offset, respectively. Moreover, the slow inhibition may have an earlier effect on excitation/inhibition imbalance. We confirm the decrease in excitation/inhibition ratio upon seizure termination in human temporal lobe epilepsy, as revealed by optogenetic approaches both in vivo in animal models and in vitro. The increase in excitation/inhibition ratio around seizure occurrence could be an indicator to detect seizures.
SUMMARY Motion powered energy harvesters could be an attractive alternative for endoscopic implan... more SUMMARY Motion powered energy harvesters could be an attractive alternative for endoscopic implant power supplies, as they are non-invasive and do not require regular battery recharges. This paper presents a novel implantable energy harvester, based on the mechanism of an automatic watch. A model of the energy conversion, from the daily physical activity to the electrical output power, is given. Output energy was calculated based on various human activity measurements.
Background Kinocardiography (KCG) is a promising new technique used to monitor cardiac mechanical... more Background Kinocardiography (KCG) is a promising new technique used to monitor cardiac mechanical function remotely. KCG is based on ballistocardiography (BCG) and seismocardiography (SCG), and measures 12 degrees-of-freedom (DOF) of body motion produced by myocardial contraction and blood flow through the cardiac chambers and major vessels. Results The integral of kinetic energy ($$ iK$$ iK ) obtained from the linear and rotational SCG/BCG signals was computed over each dimension over the cardiac cycle, and used as a marker of cardiac mechanical function. We tested the hypotheses that KCG metrics can be acquired using different sensors, and at 50 Hz. We also tested the effect of record length on the ensemble average on which the metrics were computed. Twelve healthy males were tested in the supine, head-down tilt, and head-up tilt positions to expand the haemodynamic states on which the validation was performed. Conclusions KCG metrics computed on 50 Hz and 1 kHz SCG/BCG signals we...
On-demand stimulation improves the efficacy of vagus nerve stimulation (VNS) in refractory epilep... more On-demand stimulation improves the efficacy of vagus nerve stimulation (VNS) in refractory epilepsy. The vagus nerve is the main peripheral parasympathetic connection and seizures are known to exhibit autonomic symptoms. Therefore, we hypothesized that seizure detection is possible through vagus nerve electroneurogram (VENG) recording. We developed a metric able to measure abrupt changes in amplitude and frequency of spontaneous vagus nerve action potentials. A classifier was trained using a "leave-one-out" method on a set of 6 seizures and 3 control recordings to utilize the VENG spike feature-based metric for seizure detection. We were able to detect pentylenetetrazol (PTZ) induced acute seizures in 6/6 animals during different stages of the seizure with no false detection. The classifier detected the seizure during an early stage in 3/6 animals and at the onset of tonic clonic stage of the seizure in 3/6 animals. EMG and motion artefacts often accompany epileptic activity. We showed the "epileptic" neural signal to be independent from EMG and motion artefacts. We confirmed the existence of seizure related signals in the VENG recording and proved their applicability for seizure detection. This detection might be a promising tool to improve efficacy of VNS treatment by developing new responsive stimulation systems.
Gastrointestinal stimulator implants have recently shown promising results in helping obese patie... more Gastrointestinal stimulator implants have recently shown promising results in helping obese patients lose weight. However, to place the implant, the patient currently needs to undergo an invasive surgical procedure. We report a less invasive procedure to stimulate the stomach with a gastrostimulator. After attempting fully endoscopic implantation, we more recently focused on a single incision percutaneous procedure. In both cases, the challenges in electronic design of the implant are largely similar. This article covers the work achieved to meet these and details the in vivo validation of a gastrostimulator aimed to be endoscopically placed and anchored to the stomach.
Detection precoce de crisesd’epilepsie a l’aide d’unemodelisation du comportementoscillatoire neu... more Detection precoce de crisesd’epilepsie a l’aide d’unemodelisation du comportementoscillatoire neuronal
To report an innovative spike detection algorithm that tailors its detection to the patient. Inte... more To report an innovative spike detection algorithm that tailors its detection to the patient. Interictal epileptiform activity quantification was accomplished in the setting of epileptic syndromes with continuous spike and waves during slow sleep, which is a time-consuming task for the EEG analysis. The algorithm works in three steps. Firstly, a first spike detection is made with generic parameters. Secondly, the detected spikes are used to tailor the detection algorithm to the patient; and thirdly, the resulting patient-specific detection algorithm is used to analyze individual patient with high-quality detection. Therefore, the algorithm produces a patient-specific template -hence exhibiting improved performance metrics, without the need of a priori knowledge from the experts. The system was first evaluated for EEG of three patients, against the scoring of three EEG experts, demonstrating similar performance. Later, it was evaluated against the spike and wave percentage evaluation of another expert for 17 additional records. The difference between the two evaluations was 4.4% on average, which is almost the same as the interexpert difference (4.7%). We designed a fully automated and efficient spike detection algorithm, which is liable to trim down the specialist's diagnostic time.
We propose an approach that combines a neural mass model and clinical intracranial electroencepha... more We propose an approach that combines a neural mass model and clinical intracranial electroencephalographic (iEEG) recordings to explore the potential pathophysiological mechanisms (at the neuronal population level) of ictogenesis. Thirty iEEG recordings from 10 temporal lobe epilepsy (TLE) patients around seizure onset were investigated. Physiologically meaningful parameters [average excitatory (Ae), slow (B), and fast (G) inhibitory synaptic gain] were identified during interictal to ictal transition. Four ratios (Ae/G, Ae/B, Ae/(B + G), and B/G) were derived from these parameters, and their evolution over time was analyzed. The excitation/inhibition ratio increased around seizure onset and decreased before seizure offset, indicating the impairment and re‐emergence of excitation/inhibition balance around seizure onset and before seizure offset, respectively. Moreover, the slow inhibition may have an earlier effect on excitation/inhibition imbalance. We confirm the decrease in excitation/inhibition ratio upon seizure termination in human temporal lobe epilepsy, as revealed by optogenetic approaches both in vivo in animal models and in vitro. The increase in excitation/inhibition ratio around seizure occurrence could be an indicator to detect seizures.
SUMMARY Motion powered energy harvesters could be an attractive alternative for endoscopic implan... more SUMMARY Motion powered energy harvesters could be an attractive alternative for endoscopic implant power supplies, as they are non-invasive and do not require regular battery recharges. This paper presents a novel implantable energy harvester, based on the mechanism of an automatic watch. A model of the energy conversion, from the daily physical activity to the electrical output power, is given. Output energy was calculated based on various human activity measurements.
Background Kinocardiography (KCG) is a promising new technique used to monitor cardiac mechanical... more Background Kinocardiography (KCG) is a promising new technique used to monitor cardiac mechanical function remotely. KCG is based on ballistocardiography (BCG) and seismocardiography (SCG), and measures 12 degrees-of-freedom (DOF) of body motion produced by myocardial contraction and blood flow through the cardiac chambers and major vessels. Results The integral of kinetic energy ($$ iK$$ iK ) obtained from the linear and rotational SCG/BCG signals was computed over each dimension over the cardiac cycle, and used as a marker of cardiac mechanical function. We tested the hypotheses that KCG metrics can be acquired using different sensors, and at 50 Hz. We also tested the effect of record length on the ensemble average on which the metrics were computed. Twelve healthy males were tested in the supine, head-down tilt, and head-up tilt positions to expand the haemodynamic states on which the validation was performed. Conclusions KCG metrics computed on 50 Hz and 1 kHz SCG/BCG signals we...
On-demand stimulation improves the efficacy of vagus nerve stimulation (VNS) in refractory epilep... more On-demand stimulation improves the efficacy of vagus nerve stimulation (VNS) in refractory epilepsy. The vagus nerve is the main peripheral parasympathetic connection and seizures are known to exhibit autonomic symptoms. Therefore, we hypothesized that seizure detection is possible through vagus nerve electroneurogram (VENG) recording. We developed a metric able to measure abrupt changes in amplitude and frequency of spontaneous vagus nerve action potentials. A classifier was trained using a "leave-one-out" method on a set of 6 seizures and 3 control recordings to utilize the VENG spike feature-based metric for seizure detection. We were able to detect pentylenetetrazol (PTZ) induced acute seizures in 6/6 animals during different stages of the seizure with no false detection. The classifier detected the seizure during an early stage in 3/6 animals and at the onset of tonic clonic stage of the seizure in 3/6 animals. EMG and motion artefacts often accompany epileptic activity. We showed the "epileptic" neural signal to be independent from EMG and motion artefacts. We confirmed the existence of seizure related signals in the VENG recording and proved their applicability for seizure detection. This detection might be a promising tool to improve efficacy of VNS treatment by developing new responsive stimulation systems.
Gastrointestinal stimulator implants have recently shown promising results in helping obese patie... more Gastrointestinal stimulator implants have recently shown promising results in helping obese patients lose weight. However, to place the implant, the patient currently needs to undergo an invasive surgical procedure. We report a less invasive procedure to stimulate the stomach with a gastrostimulator. After attempting fully endoscopic implantation, we more recently focused on a single incision percutaneous procedure. In both cases, the challenges in electronic design of the implant are largely similar. This article covers the work achieved to meet these and details the in vivo validation of a gastrostimulator aimed to be endoscopically placed and anchored to the stomach.
Drying is a widely used technique in sub-Saharan Africa which allows food conservation, weight re... more Drying is a widely used technique in sub-Saharan Africa which allows food conservation, weight reduction and added value for some products. However, the technique is quite complex, making the rational concept of drying devices challenging. A rational method for the design and the construction of a fruit and vegetable solar dryer is presented. A prototype was designed and constructed at the Université Libre de Bruxelles (Belgium) to test the concept and was found to be capable of drying more than 40 kg of fresh tomatoes in 10 h. A second prototype was constructed in Bandiagara (Mali) by both local craftsmen and students from the Université Libre de Bruxelles, using local materials. Speed of drying and prevention of food spoilage was far superior to that of traditional solar dryers. Based on these prototypes, a dryer industry is being constructed in Bandiagara in order to increase food self-sufficiency.
Fishing is a traditional activity that is widespread in West Africa. One of the greatest problems... more Fishing is a traditional activity that is widespread in West Africa. One of the greatest problems for fishermen and a cause of lack of food accessibility is the difficulty in conserving fish. Drying is a widely used technique in sub-Saharan Africa for preservation of fish. However, drying is a complex process, making the construction and calibration of efficient drying devices challenging. This paper presents the construction and calibration of five mobile fish dryers in Mali and, for one of them, development of a method for its use. The performances achieved far exceeded those of traditional solar dryers as drying was faster and the fish were not contaminated by being exposed to flies. Furthermore , construction and user manuals were written for the local fishermen which were well understood as the fisher-men were able to disassemble and reassemble the dryers when they were required to be moved.
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Papers by Antoine Nonclercq