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Seeuws N, De Vos M, Bertrand A. Avoiding Post-processing with Event-Based Detection in Biomedical Signals. IEEE Trans Biomed Eng 2024; PP:1-12. [PMID: 38466599 DOI: 10.1109/tbme.2024.3375759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
OBJECTIVE Finding events of interest is a common task in biomedical signal processing. The detection of epileptic seizures and signal artefacts are two key examples. Epoch-based classification is the typical machine learning framework to detect such signal events because of the straightforward application of classical machine learning techniques. Usually, post-processing is required to achieve good performance and enforce temporal dependencies. Designing the right post-processing scheme to convert these classification outputs into events is a tedious, and labor-intensive element of this framework. METHODS We propose an event-based modeling framework that directly works with events as learning targets, stepping away from ad-hoc post-processing schemes to turn model outputs into events. We illustrate the practical power of this framework on simulated data and real-world data, comparing it to epoch-based modeling approaches. RESULTS We show that event-based modeling (without tailored post-processing) performs on par with or better than epoch-based modeling with extensive post-processing. CONCLUSION These results show the power of treating events as direct learning targets, instead of using ad-hoc post-processing to obtain them, severely reducing design effort. Significance The event-based modeling framework can easily be applied to other event detection problems in signal processing, removing the need for intensive task-specific post-processing.
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Yao Y, Stebner A, Tuytelaars T, Geirnaert S, Bertrand A. Identifying temporal correlations between natural single-shot videos and EEG signals. J Neural Eng 2024; 21:016018. [PMID: 38277701 DOI: 10.1088/1741-2552/ad2333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 01/26/2024] [Indexed: 01/28/2024]
Abstract
Objective.Electroencephalography (EEG) is a widely used technology for recording brain activity in brain-computer interface (BCI) research, where understanding the encoding-decoding relationship between stimuli and neural responses is a fundamental challenge. Recently, there is a growing interest in encoding-decoding natural stimuli in a single-trial setting, as opposed to traditional BCI literature where multi-trial presentations of synthetic stimuli are commonplace. While EEG responses to natural speech have been extensively studied, such stimulus-following EEG responses to natural video footage remain underexplored.Approach.We collect a new EEG dataset with subjects passively viewing a film clip and extract a few video features that have been found to be temporally correlated with EEG signals. However, our analysis reveals that these correlations are mainly driven by shot cuts in the video. To avoid the confounds related to shot cuts, we construct another EEG dataset with natural single-shot videos as stimuli and propose a new set of object-based features.Main results.We demonstrate that previous video features lack robustness in capturing the coupling with EEG signals in the absence of shot cuts, and that the proposed object-based features exhibit significantly higher correlations. Furthermore, we show that the correlations obtained with these proposed features are not dominantly driven by eye movements. Additionally, we quantitatively verify the superiority of the proposed features in a match-mismatch task. Finally, we evaluate to what extent these proposed features explain the variance in coherent stimulus responses across subjects.Significance.This work provides valuable insights into feature design for video-EEG analysis and paves the way for applications such as visual attention decoding.
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Affiliation(s)
- Yuanyuan Yao
- Department of Electrical Engineering, STADIUS, KU Leuven, Leuven, Belgium
| | - Axel Stebner
- Department of Electrical Engineering, PSI, KU Leuven, Leuven, Belgium
| | - Tinne Tuytelaars
- Department of Electrical Engineering, PSI, KU Leuven, Leuven, Belgium
| | - Simon Geirnaert
- Department of Electrical Engineering, STADIUS, Department of Neurosciences, ExpORL, KU Leuven, Leuven, Belgium
| | - Alexander Bertrand
- Department of Electrical Engineering, STADIUS, KU Leuven, Leuven, Belgium
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Rotaru I, Geirnaert S, Heintz N, Van de Ryck I, Bertrand A, Francart T. What are we reallydecoding? Unveiling biases in EEG-based decoding of the spatial focus of auditory attention. J Neural Eng 2024; 21:016017. [PMID: 38266281 DOI: 10.1088/1741-2552/ad2214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 01/24/2024] [Indexed: 01/26/2024]
Abstract
Objective.Spatial auditory attention decoding (Sp-AAD) refers to the task of identifying the direction of the speaker to which a person is attending in a multi-talker setting, based on the listener's neural recordings, e.g. electroencephalography (EEG). The goal of this study is to thoroughly investigate potential biases when training such Sp-AAD decoders on EEG data, particularly eye-gaze biases and latent trial-dependent confounds, which may result in Sp-AAD models that decode eye-gaze or trial-specific fingerprints rather than spatial auditory attention.Approach.We designed a two-speaker audiovisual Sp-AAD protocol in which the spatial auditory and visual attention were enforced to be either congruent or incongruent, and we recorded EEG data from sixteen participants undergoing several trials recorded at distinct timepoints. We trained a simple linear model for Sp-AAD based on common spatial patterns filters in combination with either linear discriminant analysis (LDA) or k-means clustering, and evaluated them both across- and within-trial.Main results.We found that even a simple linear Sp-AAD model is susceptible to overfitting to confounding signal patterns such as eye-gaze and trial fingerprints (e.g. due to feature shifts across trials), resulting in artificially high decoding accuracies. Furthermore, we found that changes in the EEG signal statistics across trials deteriorate the trial generalization of the classifier, even when the latter is retrained on the test trial with an unsupervised algorithm.Significance.Collectively, our findings confirm that there exist subtle biases and confounds that can strongly interfere with the decoding of spatial auditory attention from EEG. It is expected that more complicated non-linear models based on deep neural networks, which are often used for Sp-AAD, are even more vulnerable to such biases. Future work should perform experiments and model evaluations that avoid and/or control for such biases in Sp-AAD tasks.
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Affiliation(s)
- Iustina Rotaru
- Department of Neurosciences, ExpORL, KU Leuven, Herestraat 49 bus 721, B-3000 Leuven, Belgium
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
| | - Simon Geirnaert
- Department of Neurosciences, ExpORL, KU Leuven, Herestraat 49 bus 721, B-3000 Leuven, Belgium
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
- Leuven.AI-KU Leuven Institute for AI, Leuven, Belgium
| | - Nicolas Heintz
- Department of Neurosciences, ExpORL, KU Leuven, Herestraat 49 bus 721, B-3000 Leuven, Belgium
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
- Leuven.AI-KU Leuven Institute for AI, Leuven, Belgium
| | - Iris Van de Ryck
- Department of Neurosciences, ExpORL, KU Leuven, Herestraat 49 bus 721, B-3000 Leuven, Belgium
| | - Alexander Bertrand
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
- Leuven.AI-KU Leuven Institute for AI, Leuven, Belgium
| | - Tom Francart
- Department of Neurosciences, ExpORL, KU Leuven, Herestraat 49 bus 721, B-3000 Leuven, Belgium
- Leuven.AI-KU Leuven Institute for AI, Leuven, Belgium
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Ng D, Bertrand A, Sanfilippo R, Callegaro D. Deciding individual treatment for primary retroperitoneal sarcoma. Expert Rev Anticancer Ther 2023; 23:1169-1178. [PMID: 37791587 DOI: 10.1080/14737140.2023.2266137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 09/28/2023] [Indexed: 10/05/2023]
Abstract
INTRODUCTION Retroperitoneal sarcomas (RPS) are rare mesenchymal tumors that account for only 0.1-0.2% of all malignancies. Management of this disease is challenging, and resection remains the cornerstone of treatment. Ongoing international collaboration has expanded our knowledge of this disease, allowing for a more personalized approach to RPS patients resulting in improved survival over time. Due to the heterogeneity of RPS, with differing recurrence patterns and sensitivities to neoadjuvant therapies based on histology and grade, management of RPS should be tailored to the individual patient. AREAS COVERED Our review focuses on a histology-driven approach in the management of primary RPS. We searched relevant articles from 1993 to 2023 that investigated prognostic factors and treatment of patients with RPS and summarized recent advances and future directions in the field. EXPERT OPINION Deeper understanding of the role of neoadjuvant radiotherapy and ongoing trials investigating the role of neoadjuvant chemotherapy will potentially contribute to the development of individualized treatment pathways.
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Affiliation(s)
- Deanna Ng
- Department of Surgery, University of Toronto, Toronto, ON, Canada
| | | | - Roberta Sanfilippo
- Department of Medical Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Dario Callegaro
- Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
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Dan J, Foged MT, Vandendriessche B, Van Paesschen W, Bertrand A. Sensor selection and miniaturization limits for detection of interictal epileptiform discharges with wearable EEG. J Neural Eng 2023; 20. [PMID: 36630712 DOI: 10.1088/1741-2552/acb231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 01/11/2023] [Indexed: 01/12/2023]
Abstract
Objective.The goal of this paper is to investigate the limits of electroencephalography (EEG) sensor miniaturization in a set-up consisting of multiple galvanically isolated EEG units to record interictal epileptiform discharges (IEDs), referred to as 'spikes', in people with epilepsy.Approach.A dataset of high-density EEG recordings (257 channels) was used to emulate local EEG sensor units with short inter-electrode distances. A computationally efficient sensor selection and interictal spike detection algorithm was developed and used to assess the influence of the inter-electrode distance and the number of such EEG units on spike detection performance. Signal-to-noise ratio, correlation with a clinical-grade IEDs detector and Cohen's kappa coefficient of agreement were used to quantify performance. Bayesian statistics were used to confirm the statistical significance of the observed results.Main results.We found that EEG recording equipment should be specifically designed to measure the small signal power at short inter-electrode distance by providing an input referred noise<300 nV. We also found that an inter-electrode distance of minimum 5 cm between electrodes in a setup with a minimum of two EEG units is required to obtain near equivalent performance in interictal spike detection to standard EEG.Significance.These findings provide design guidelines for miniaturizing EEG systems for long term ambulatory monitoring of interictal spikes in epilepsy patients.
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Affiliation(s)
- Jonathan Dan
- Department of Electrical Engineering (ESAT), STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Kasteelpark Arenberg 10, 3001 Leuven, Belgium.,Byteflies, Borsbeeksebrug 22, 2600 Berchem, Belgium
| | - Mette Thrane Foged
- Rigshospitalet, Neurobiology Research Unit, 28 Juliane Maries Vej, DK-2100 Copenhagen, Denmark
| | - Benjamin Vandendriessche
- Byteflies, Borsbeeksebrug 22, 2600 Berchem, Belgium.,Department of Electrical, Computer, and Systems Engineering, Case Western Reserve University, Cleveland, OH, United States of America
| | - Wim Van Paesschen
- Department of neurology, UZ Leuven, Herestraat 49, 3000 Leuven, Belgium
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Benarroch L, Bertrand A, Beuvin M, Nelson I, Naouar N, Simonet F, Dina C, Pionneau C, Schott J, Yaou RB, Bonne G. P.145 Identification of potential genetic modifiers underlying phenotypic variability in a French family with striated muscle laminopathies. Neuromuscul Disord 2022. [DOI: 10.1016/j.nmd.2022.07.273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Bertrand A, Paecklar A, Barbier T, Gascoin F. Rapid synthesis process and characterization for high purity sodium thioantimoniate nonahydrate. Dalton Trans 2022; 51:11340-11345. [PMID: 35815476 DOI: 10.1039/d2dt01520j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
For the first time, Na3SbS4·9H2O, also known as Schlippe's salt, has been synthesized through high-energy ball milling. This innovative synthesis way allows for obtaining high purity thioantimonate nonahydrate with around 90% yield in only approximately four hours. To validate the synthesis route described herein, the crystal structure has been refined, at room temperature, through high-resolution X-ray diffraction, pair distribution function analysis and energy dispersive spectrometry. Dehydration and rehydration of the compound have also been studied by thermogravimetric analysis and differential scanning calorimetry.
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Affiliation(s)
- A Bertrand
- CRISMAT, UMR6508 CNRS ENSICAEN, 6 bd Maréchal Juin, 14050 CAEN cedex 4, France.
| | - A Paecklar
- CRISMAT, UMR6508 CNRS ENSICAEN, 6 bd Maréchal Juin, 14050 CAEN cedex 4, France.
| | - T Barbier
- CRISMAT, UMR6508 CNRS ENSICAEN, 6 bd Maréchal Juin, 14050 CAEN cedex 4, France.
| | - F Gascoin
- CRISMAT, UMR6508 CNRS ENSICAEN, 6 bd Maréchal Juin, 14050 CAEN cedex 4, France.
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Faganello D, Meunier P, Bertrand A, Toussirot E, Coury-Lucas F, Seror R, Le Meledo G, Avouac J, Germain V, Shima D, Richez C, Truchetet ME, Schaeverbeke T, Kostine M. AB0410 EVOLUTION OF MONOCLONAL GAMMOPATHY OF UNDETERMINED SIGNIFICANCE IN PATIENTS TREATED WITH JAK INHIBITORS FOR RHEUMATIC DISEASES (JAKPIC STUDY). Ann Rheum Dis 2022. [DOI: 10.1136/annrheumdis-2022-eular.3659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BackgroundMonoclonal Gammopathy of Undetermined Significance (MGUS) is common in patients with inflammatory rheumatic diseases but there are scarce data regarding the effect of disease-modifying antirheumatic drugs (DMARDs) on this pre-malignant condition. Recently, preclinical data and phase I trial have shown efficacy of JAK inhibitors (JAKi) in multiple myeloma.ObjectivesWe aimed to evaluate the impact of JAKi on MGUS when initiated for an active rheumatic disease.MethodsPatients with monoclonal abnormality prior to JAKi initiation for an active rheumatic disease were identified through the MAJIK-SFR Registry, a french multicentre prospective study, and a call for observation via the “Club Rhumatismes et Inflammations”. Clinical and biological data were collected using a standardised case report form.ResultsNineteen patients were identified, 10 women and 9 men, with a mean age of 65 years and a diagnosis of rheumatoid arthritis (n=14), psoriatic arthritis (n=3) or spondyloarthritis (n=2). The JAKi prescribed was baricitinib (n=8), tofacitinib (n=6) or upadacitinib (n=5), with a mean duration of 13 months.Sixteen patients had individualized serum monoclonal protein (IgG Kappa n=9; IgG Lambda n=6; IgM Kappa n=3; IgA Lambda n=1) ranging from 0,16g/dL to 2,3g/dL. With a follow-up of 2 to 47 months, 8 of 16 patients experienced a decrease in serum monoclonal protein level and 8 had a stable serum monoclonal protein level. The maximal decrease observed was an initial IgG Kappa of 2.3g/dL decreasing to 0.2g/dL at month 14. During follow-up, two patients did not have any detectable serum monoclonal protein on serum electrophoresis (initial value of 5.2g/l and 1.6g/l), but still a positive immunofixation. One patient had bone marrow aspirate with 8% of plasma cells before JAKi introduction and 3% after 4 months of treatment.Three patients did not have initial measurable spike but a positive immunofixation that became negative at month 8 and 11 (IgG Lambda, n=2) or stable (IgG Kappa, n=1).ConclusionThis study brings reassuring and promising data on the MGUS evolution in patients treated with JAKi for rheumatic diseases, which may guide the choice of treatment in patients with both conditions.References[1]Berenson JR, To J, Spektor TM, et al. A Phase I Study of Ruxolitinib, Lenalidomide, and Steroids for Patients with Relapsed/Refractory Multiple MyelomaClin Cancer Res. 2020 May 15;26(10):2346-2353.AcknowledgementsMAJIK-SFR Registry and Club Rhumatismes et InflammationsDisclosure of InterestsNone declared
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Birdi J, D'hooge J, Bertrand A. Spatially Variant Ultrasound Attenuation Mapping Using a Regularized Linear Least-Squares Approach. IEEE Trans Ultrason Ferroelectr Freq Control 2022; 69:1596-1609. [PMID: 35263252 DOI: 10.1109/tuffc.2022.3157949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Quantitative ultrasound methods aim to estimate the acoustic properties of the underlying medium, such as the attenuation and backscatter coefficients, and have applications in various areas including tissue characterization. In practice, tissue heterogeneity makes the coefficient estimation challenging. In this work, we propose a computationally efficient algorithm to map spatial variations of the attenuation coefficient. Our proposed approach adopts a fast, linear least-squares strategy to fit the signal model to data from pulse-echo measurements. As opposed to existing approaches, we directly estimate the attenuation map, that is, the local attenuation coefficient at each axial location by solving a joint estimation problem. In particular, we impose a physical model that couples all these local estimates and combine it with a smooth regularization to obtain a smooth map. Compared to the conventional spectral log difference method and the more recent ALGEBRA approach, we demonstrate that the attenuation estimates obtained by our method are more accurate and better correlate with the ground-truth attenuation profiles over a wide range of spatial and contrast resolutions.
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Geirnaert S, Francart T, Bertrand A. Time-adaptive Unsupervised Auditory Attention Decoding Using EEG-based Stimulus Reconstruction. IEEE J Biomed Health Inform 2022; 26:3767-3778. [PMID: 35344501 DOI: 10.1109/jbhi.2022.3162760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The goal of auditory attention decoding (AAD) is to determine to which speaker out of multiple competing speakers a listener is attending based on the brain signals recorded via, e.g., electroencephalography (EEG). AAD algorithms are a fundamental building block of so-called neuro-steered hearing devices that would allow identifying the speaker that should be amplified based on the brain activity. A common approach is to train a subject-specific stimulus decoder that reconstructs the amplitude envelope of the attended speech signal. However, training this decoder requires a dedicated 'ground-truth' EEG recording of the subject under test, during which the attended speaker is known. Furthermore, this decoder remains fixed during operation and can thus not adapt to changing conditions and situations. Therefore, we propose an online time-adaptive unsupervised stimulus reconstruction method that continuously and automatically adapts over time when new EEG and audio data are streaming in. The adaptive decoder does not require ground-truth attention labels obtained from a training session with the end-user and instead can be initialized with a generic subject-independent decoder or even completely random values. We propose two different implementations: a sliding window and recursive implementation, which we extensively validate on three independent datasets based on multiple performance metrics. We show that the proposed time-adaptive unsupervised decoder outperforms a time-invariant supervised decoder, representing an important step toward practically applicable AAD algorithms for neuro-steered hearing devices.
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Schelles M, Wouters J, Asamoah B, Mc Laughlin M, Bertrand A. Objective evaluation of stimulation artefact removal techniques in the context of neural spike sorting. J Neural Eng 2022; 19. [DOI: 10.1088/1741-2552/ac4ecf] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 01/25/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Objective - We present a framework to objectively test and compare stimulation artefact removal techniques in the context of neural spike sorting. Approach - To this end, we used realistic hybrid ground-truth spiking data, with superimposed artefacts from in vivo recordings. We used the framework to evaluate and compare several techniques: blanking, template subtraction by averaging, linear regression, and a multi-channel Wiener filter (MWF). Main results - Our study demonstrates that blanking and template subtraction result in a poorer spike sorting performance than linear regression and MWF, while the latter two perform similarly. Finally, to validate the conclusions found from the hybrid evaluation framework, we also performed a qualitative analysis on in vivo recordings without artificial manipulations. Significance - Our framework allows direct quantification of the impact of the residual artefact on the spike sorting accuracy, thereby allowing for a more objective and more relevant comparison compared to indirect signal quality metrics that are estimated from the signal statistics. Furthermore, the availability of a ground truth in the form of single-unit spiking activity also facilitates a better estimation of such signal quality metrics.
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Mundanad Narayanan A, Zink R, Bertrand A. EEG miniaturization limits for stimulus decoding with EEG sensor networks. J Neural Eng 2021; 18. [PMID: 34517358 DOI: 10.1088/1741-2552/ac2629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 09/13/2021] [Indexed: 11/12/2022]
Abstract
Objective. Unobtrusive electroencephalography (EEG) monitoring in everyday life requires the availability of highly miniaturized EEG devices (mini-EEGs), which ideally consist of a wireless node with a small scalp area footprint, in which the electrodes, amplifier and wireless radio are embedded. By attaching a multitude of mini-EEGs at relevant positions on the scalp, a wireless 'EEG sensor network' (WESN) can be formed. However, each mini-EEG in the network only has access to its own local electrodes, thereby recording local scalp potentials with short inter-electrode distances. This is unlike using traditional cap-EEG, which by the virtue of re-referencing can measure EEG across arbitrarily large distances on the scalp. We evaluate the implications and limitations of such far-driven miniaturization on neural decoding performance.Approach. We collected 255-channel EEG data in an auditory attention decoding (AAD) task. As opposed to previous studies with a lower channel density, this new high-density dataset allows emulation of mini-EEGs with inter-electrode distances down to 1 cm in order to identify and quantify the lower bound on miniaturization for EEG-based stimulus decoding.Main results. We demonstrate that the performance remains reasonably stable for inter-electrode distances down to 3 cm, but decreases quickly for shorter distances if the mini-EEG nodes can be placed at optimal scalp locations and orientations selected by a data-driven algorithm.Significance. The results indicate the potential for the use of mini-EEGs in a WESN context for AAD applications and provide guidance on inter-electrode distances while designing such devices for neuro-steered hearing devices.
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Affiliation(s)
- Abhijith Mundanad Narayanan
- KU Leuven, Dept. of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics (STADIUS), Kasteelpark Arenberg 10, B-3001 Leuven, Belgium.,Leuven.AI-KU Leuven institute for AI, B-3000 Leuven, Belgium
| | - Rob Zink
- KU Leuven, Dept. of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics (STADIUS), Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
| | - Alexander Bertrand
- KU Leuven, Dept. of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics (STADIUS), Kasteelpark Arenberg 10, B-3001 Leuven, Belgium.,Leuven.AI-KU Leuven institute for AI, B-3000 Leuven, Belgium
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Brito AF, Tremblay GF, Bertrand A, Castonguay Y, Bélanger G, Lafrenière C, Martineau R, Berthiaume R. Omasal flow of nonstructural carbohydrates and nitrogenous compounds in lactating dairy cows fed diets containing timothy cut in the afternoon or morning. J Dairy Sci 2021; 104:12459-12471. [PMID: 34593224 DOI: 10.3168/jds.2021-20807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/16/2021] [Indexed: 11/19/2022]
Abstract
Shifting the cutting of grass from morning to afternoon has been shown to increase the concentration of nonstructural carbohydrates (NSC) in forages. We compared the effects of diets (66:34, forage:concentrate ratio) containing a mix (% of the diet dry matter) of baleages (46.5%) and silages (19.3%) harvested from timothy cut in the afternoon (p.m.-cut TIM diet) or morning (a.m.-cut TIM diet) on omasal flows of NSC and nitrogenous fractions, ruminal and total-tract digestibilities of nutrients, plasma concentration of AA, and milk yield and composition. Eight ruminally cannulated Holstein cows averaging (mean ± standard deviation) 31.4 ± 6.13 kg/d of milk, 136 ± 17.0 d in milk, and 611 ± 66.4 kg of body weight in the beginning of the experiment were used in a crossover design with 21-d periods (14 d for diet adaptation and 7 d for data and sample collection). Intake of total ethanol-soluble carbohydrates (TESC; +150 g/d), starch (+129 g/d), and total NSC (TESC plus starch = +278 g/d) was greater with feeding the p.m.- than the a.m.-cut TIM diet. Likewise, the apparent ruminal digestibilities of TESC (+149 g/d), starch (+167 g/d), and total NSC (+316 g/d) increased in the p.m.-cut TIM diet. Diets, however, had no effect on the omasal flows and apparent ruminal and total-tract digestibilities of dry matter and organic matter. Intake of N increased in cows fed the p.m.- versus the a.m.-cut TIM diet (562 and 528 g/d, respectively) despite no effect of diets on dry matter intake. Diets did not affect the omasal flows of total nonammonia N, total bacterial nonammonia N, nonammonia and nonbacterial N, and individual AA, and the efficiency of microbial protein synthesis in the rumen. Contrarily, supply of rumen-degradable protein increased (+9.2%) in cows fed the p.m.-cut TIM diet, with this response driven by the 6.4% increase in N intake. Plasma concentrations of essential and nonessential AA followed the omasal flow of AA and were not changed by diets. Feeding the p.m.- versus the a.m.-cut diet significantly increased yields of 4% fat-corrected milk and milk fat, and tended to increase energy-corrected milk, milk true protein, and milk lactose yields. Overall, feeding the p.m.-cut TIM diet to mid-lactation dairy cows did not improve microbial protein synthesis and omasal flow of AA, and these responses were in line with the lack of a treatment effect on dry matter intake.
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Affiliation(s)
- A F Brito
- University of New Hampshire, Department of Agriculture, Nutrition, and Food Systems, Durham 03824.
| | - G F Tremblay
- Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada, Québec City, QC, G1V 2J3, Canada
| | - A Bertrand
- Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada, Québec City, QC, G1V 2J3, Canada
| | - Y Castonguay
- Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada, Québec City, QC, G1V 2J3, Canada
| | - G Bélanger
- Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada, Québec City, QC, G1V 2J3, Canada
| | - C Lafrenière
- Agricultural Research Station, Université du Québec en Abitibi-Témiscamingue, Notre-Dame-du-Nord, QC J0Z 3B0, Canada
| | - R Martineau
- Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, QC, J1M 0C8, Canada
| | - R Berthiaume
- Private Consultant, Expert in Forage Systems, Sherbrooke, QC, J1M 0A8, Canada
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Schmid F, Huyghebaert T, Bertrand A, Cartier M, Deleau K, Henry A, Stefaniak N. Le burn-out est-il une entité nosographique distincte ? Psychologie Française 2021. [DOI: 10.1016/j.psfr.2020.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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15
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Birdi J, Muraleedharan A, D'hooge J, Bertrand A. Fast linear least-squares method for ultrasound attenuation and backscatter estimation. Ultrasonics 2021; 116:106503. [PMID: 34171752 DOI: 10.1016/j.ultras.2021.106503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/13/2021] [Accepted: 06/08/2021] [Indexed: 06/13/2023]
Abstract
The ultrasonic attenuation and backscatter coefficients of tissues are relevant acoustic parameters due to their wide range of clinical applications. In this paper, a linear least-squares method for the estimation of these coefficients in a homogeneous region of interest based on pulse-echo measurements is proposed. The method efficiently fits an ultrasound backscattered signal model to the measurements in both the frequency and depth dimension simultaneously at a low computational cost. It is demonstrated that the inclusion of depth information has a positive effect particularly on the accuracy of the estimated attenuation. The sensitivity of the attenuation and backscatter coefficients' estimates to several predefined parameters such as the window length, window overlap and usable bandwidth of the spectrum is also studied. Comparison of the proposed method with a benchmark approach based on dynamic programming highlights better performance of our method in estimating these coefficients, both in terms of accuracy and computation time. Further analysis of the computation time as a function of the predefined parameters indicates our method's potential to be used in real-time clinical settings.
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Affiliation(s)
- Jasleen Birdi
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Department of Electrical Engineering (ESAT), KU Leuven, Leuven, Belgium.
| | - Arun Muraleedharan
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Department of Electrical Engineering (ESAT), KU Leuven, Leuven, Belgium
| | - Jan D'hooge
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
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Abstract
OBJECTIVE Noise and disturbances hinder effective interpretation of recorded ECG. To identify the clean parts of a recording, free from such disturbances, various quality indicators have been developed. Previous instances of these indicators focus on human-defined desirable properties of a clean signal. The reliance on human-specified properties places an inherent limitation on the potential power of signal quality indicators. To move away from this limitation, we propose a data-driven quality indicator. METHODS We use an unsupervised deep learning model, the auto-encoder, to derive the quality indicator. For different quality assessment settings we compare the performance of our quality indicator with traditional indicators. RESULTS The data-driven method performs consistently strong across tasks while performance of the traditional indicators varies strongly from task to task. CONCLUSION This strong performance indicates the potential of data-driven quality indicators for use in ECG processing, removing the reliance on expert-specified desirable properties. SIGNIFICANCE The proposed methodology can easily be extended towards learning quality indicators in other data modalities.
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Vrillon A, Hubsch C, Bertrand A, Decq P, Catala M. A case of extreme hydrocephalus in a 67-year-old man whose professional and social lives were normal. Neurochirurgie 2021; 68:349-351. [PMID: 34339770 DOI: 10.1016/j.neuchi.2021.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 07/27/2021] [Indexed: 10/20/2022]
Affiliation(s)
- A Vrillon
- Department of Neurology, Pitié-Salpêtrière Hospital, Paris, France
| | - C Hubsch
- Department of Neurology, Rothschild Ophthalmologic Foundation, Paris, France
| | - A Bertrand
- Department of Neuroradiology, Pitié-Salpêtrière Hospital, Paris, France
| | - P Decq
- Department of Neurosurgery, Beaujon Hospital, Clichy, France
| | - M Catala
- Department of Neurology, Pitié-Salpêtrière Hospital, Paris, France; CNRS UMR7622 Sorbonne Université, Inserm ERL U1156, Paris, France.
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Strypsteen T, Bertrand A. End-to-end learnable EEG channel selection for deep neural networks with Gumbel-softmax. J Neural Eng 2021; 18. [PMID: 34225257 DOI: 10.1088/1741-2552/ac115d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 07/05/2021] [Indexed: 12/26/2022]
Abstract
Objective.To develop an efficient, embedded electroencephalogram (EEG) channel selection approach for deep neural networks, allowing us to match the channel selection to the target model, while avoiding the large computational burdens of wrapper approaches in conjunction with neural networks.Approach.We employ a concrete selector layer to jointly optimize the EEG channel selection and network parameters. This layer uses a Gumbel-softmax trick to build continuous relaxations of the discrete parameters involved in the selection process, allowing them be learned in an end-to-end manner with traditional backpropagation. As the selection layer was often observed to include the same channel twice in a certain selection, we propose a regularization function to mitigate this behavior. We validate this method on two different EEG tasks: motor execution and auditory attention decoding. For each task, we compare the performance of the Gumbel-softmax method with a baseline EEG channel selection approach tailored towards this specific task: mutual information and greedy forward selection with the utility metric respectively.Main results.Our experiments show that the proposed framework is generally applicable, while performing at least as well as (and often better than) these state-of-the-art, task-specific approaches.Significance.The proposed method offers an efficient, task- and model-independent approach to jointly learn the optimal EEG channels along with the neural network weights.
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Affiliation(s)
- Thomas Strypsteen
- KU Leuven, Department of Electrical Engineering (ESAT) STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics with Leuven.AI - KU Leuven institute for AI, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
| | - Alexander Bertrand
- KU Leuven, Department of Electrical Engineering (ESAT) STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics with Leuven.AI - KU Leuven institute for AI, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
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Wouters J, Kloosterman F, Bertrand A. A data-driven spike sorting feature map for resolving spike overlap in the feature space. J Neural Eng 2021; 18. [PMID: 34181592 DOI: 10.1088/1741-2552/ac0f4a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 06/28/2021] [Indexed: 11/12/2022]
Abstract
Objective.Spike sorting is the process of extracting neuronal action potentials, or spikes, from an extracellular brain recording, and assigning each spike to its putative source neuron. Spike sorting is usually treated as a clustering problem. However, this clustering process is known to be affected by overlapping spikes. Existing methods for resolving spike overlap typically require an expensive post-processing of the clustering results. In this paper, we propose the design of a domain-specific feature map, which enables the resolution of spike overlap directly in the feature space.Approach.The proposed domain-specific feature map is based on a neural network architecture that is trained to simultaneously perform spike sorting and spike overlap resolution. Overlapping spikes clusters can be identified in the feature space through a linear relation with the single-neuron clusters for which the neurons contribute to the overlapping spikes. To aid the feature map training, a data augmentation procedure is presented that is based on biophysical simulations.Main results.We demonstrate the potential of our method on independent and realistic test data. We show that our novel approach for resolving spike overlap generalizes to unseen and realistic test data. Furthermore, the sorting performance of our method is shown to be similar to the state-of-the-art, but our method does not assume the availability of spike templates for resolving spike overlap.Significance.Resolving spike overlap directly in the feature space, results in an overall simplified spike sorting pipeline compared to the state-of-the-art. For the state-of-the-art, the overlapping spike snippets exhibit a large spread in the feature space and do not appear as concentrated clusters. This can lead to biased spike template estimates which affect the sorting performance of the state-of-the-art. In our proposed approach, overlapping spikes form concentrated clusters and spike overlap resolution does not depend on the availability of spike templates.
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Affiliation(s)
- J Wouters
- KU Leuven, Department of Electrical Engineering (ESAT), STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics and Leuven., Leuven, Belgium
| | - F Kloosterman
- Neuro-Electronics Research Flanders (NERF), Leuven, Belgium.,KU Leuven, Brain & Cognition Research Unit, Leuven, Belgium.,VIB, Leuven, Belgium
| | - A Bertrand
- KU Leuven, Department of Electrical Engineering (ESAT), STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics and Leuven., Leuven, Belgium
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20
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Livingston DP, Bertrand A, Wisniewski M, Tisdale R, Tuong T, Gusta LV, Artlip T. Factors contributing to ice nucleation and sequential freezing of leaves in wheat. Planta 2021; 253:124. [PMID: 34014374 PMCID: PMC8137482 DOI: 10.1007/s00425-021-03637-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 05/01/2021] [Indexed: 06/03/2023]
Abstract
Anatomical, metabolic and microbial factors were identified that contribute to sequential freezing in wheat leaves and likely contribute to supercooling in the youngest leaves and potentially meristematic regions. Infrared thermography (IR) has been used to observe wheat leaves freezing independently and in an age-related sequence with older leaves freezing first. To determine mechanisms that might explain this sequence of freezing several analytical approaches were used: (1) The size of xylem vessels, in proximity to where freezing initiated, was measured to see if capillary freezing point depression explained sequential freezing. The sequence of freezing in the four youngest leaves was correlated, with the largest vessels freezing first. (2) Carbohydrate and amino acids were analyzed to determine if solute concentrations as well as interactions with membranes explained the freezing sequence. Sucrose was highly correlated to the freezing sequence for all leaves suggesting a prominent role for this sugar as compared to other simple sugars and fructans. Among individual free amino acids proline and serine were correlated to the freezing sequence, with younger leaves having the highest concentrations. (3) Microflora within and on leaf surfaces were determined to measure potential freezing initiation. Levels of bacteria and fungi were correlated to the freezing sequence for all leaves, and species or genera associated with high ice nucleation activity were absent in younger leaves. Moisture content and transcript expression of ice binding proteins were also measured. As expected, our results show that no single mechanism explains the freezing sequence observed via infrared analyses. While these multiple mechanisms are operative at different levels according to the leaf age, they seem to converge when it comes to the protection of vital meristematic tissues. This provides potential phenotypic characters that could be used by breeders to develop more winter-hardy genotypes.
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Affiliation(s)
- D P Livingston
- USDA-ARS and North Carolina State University, Raleigh, NC, 27607, USA.
| | - A Bertrand
- Quebec Research and Development Centre, Agriculture and Agri-Food Canada, 2560 Hochelaga Boulevard, Québec, QC, G1V 2J3, Canada
| | - M Wisniewski
- USDA-ARS, Appalachian Fruit Research Station, Kearneysville, WV, USA
- Virginia Polytechnic Institute, Blacksburg, VA, 24061, USA
| | - R Tisdale
- USDA-ARS and North Carolina State University, Raleigh, NC, 27607, USA
| | - T Tuong
- USDA-ARS and North Carolina State University, Raleigh, NC, 27607, USA
| | - L V Gusta
- Department of Plant Science, Univ Saskatchewan, Saskatoon, Canada
| | - T Artlip
- USDA-ARS, Appalachian Fruit Research Station, Kearneysville, WV, 25430, USA
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21
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Vandecappelle S, Deckers L, Das N, Ansari AH, Bertrand A, Francart T. EEG-based detection of the locus of auditory attention with convolutional neural networks. eLife 2021; 10:e56481. [PMID: 33929315 PMCID: PMC8143791 DOI: 10.7554/elife.56481] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/28/2021] [Indexed: 01/16/2023] Open
Abstract
In a multi-speaker scenario, the human auditory system is able to attend to one particular speaker of interest and ignore the others. It has been demonstrated that it is possible to use electroencephalography (EEG) signals to infer to which speaker someone is attending by relating the neural activity to the speech signals. However, classifying auditory attention within a short time interval remains the main challenge. We present a convolutional neural network-based approach to extract the locus of auditory attention (left/right) without knowledge of the speech envelopes. Our results show that it is possible to decode the locus of attention within 1-2 s, with a median accuracy of around 81%. These results are promising for neuro-steered noise suppression in hearing aids, in particular in scenarios where per-speaker envelopes are unavailable.
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Affiliation(s)
- Servaas Vandecappelle
- Department of Neurosciences, Experimental Oto-rhino-laryngologyLeuvenBelgium
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data AnalyticsLeuvenBelgium
| | - Lucas Deckers
- Department of Neurosciences, Experimental Oto-rhino-laryngologyLeuvenBelgium
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data AnalyticsLeuvenBelgium
| | - Neetha Das
- Department of Neurosciences, Experimental Oto-rhino-laryngologyLeuvenBelgium
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data AnalyticsLeuvenBelgium
| | - Amir Hossein Ansari
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data AnalyticsLeuvenBelgium
| | - Alexander Bertrand
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data AnalyticsLeuvenBelgium
| | - Tom Francart
- Department of Neurosciences, Experimental Oto-rhino-laryngologyLeuvenBelgium
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22
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Vandecappelle S, Deckers L, Das N, Ansari AH, Bertrand A, Francart T. EEG-based detection of the locus of auditory attention with convolutional neural networks. eLife 2021; 10:56481. [PMID: 33929315 DOI: 10.1101/475673] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/28/2021] [Indexed: 05/27/2023] Open
Abstract
In a multi-speaker scenario, the human auditory system is able to attend to one particular speaker of interest and ignore the others. It has been demonstrated that it is possible to use electroencephalography (EEG) signals to infer to which speaker someone is attending by relating the neural activity to the speech signals. However, classifying auditory attention within a short time interval remains the main challenge. We present a convolutional neural network-based approach to extract the locus of auditory attention (left/right) without knowledge of the speech envelopes. Our results show that it is possible to decode the locus of attention within 1-2 s, with a median accuracy of around 81%. These results are promising for neuro-steered noise suppression in hearing aids, in particular in scenarios where per-speaker envelopes are unavailable.
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Affiliation(s)
- Servaas Vandecappelle
- Department of Neurosciences, Experimental Oto-rhino-laryngology, Leuven, Belgium
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, Leuven, Belgium
| | - Lucas Deckers
- Department of Neurosciences, Experimental Oto-rhino-laryngology, Leuven, Belgium
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, Leuven, Belgium
| | - Neetha Das
- Department of Neurosciences, Experimental Oto-rhino-laryngology, Leuven, Belgium
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, Leuven, Belgium
| | - Amir Hossein Ansari
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, Leuven, Belgium
| | - Alexander Bertrand
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, Leuven, Belgium
| | - Tom Francart
- Department of Neurosciences, Experimental Oto-rhino-laryngology, Leuven, Belgium
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23
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Abstract
When multiple speakers talk simultaneously, a hearing device cannot identify which of these speakers the listener intends to attend to. Auditory attention decoding (AAD) algorithms can provide this information by, for example, reconstructing the attended speech envelope from electroencephalography (EEG) signals. However, these stimulus reconstruction decoders are traditionally trained in a supervised manner, requiring a dedicated training stage during which the attended speaker is known. Pre-trained subject-independent decoders alleviate the need of having such a per-user training stage but perform substantially worse than supervised subject-specific decoders that are tailored to the user. This motivates the development of a new unsupervised self-adapting training/updating procedure for a subject-specific decoder, which iteratively improves itself on unlabeled EEG data using its own predicted labels. This iterative updating procedure enables a self-leveraging effect, of which we provide a mathematical analysis that reveals the underlying mechanics. The proposed unsupervised algorithm, starting from a random decoder, results in a decoder that outperforms a supervised subject-independent decoder. Starting from a subject-independent decoder, the unsupervised algorithm even closely approximates the performance of a supervised subject-specific decoder. The developed unsupervised AAD algorithm thus combines the two advantages of a supervised subject-specific and subject-independent decoder: it approximates the performance of the former while retaining the `plug-and-play character of the latter. As the proposed algorithm can be used to automatically adapt to new users, as well as over time when new EEG data is being recorded, it contributes to more practical neuro-steered hearing devices.
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24
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Geirnaert S, Francart T, Bertrand A. Fast EEG-Based Decoding Of The Directional Focus Of Auditory Attention Using Common Spatial Patterns. IEEE Trans Biomed Eng 2021; 68:1557-1568. [PMID: 33095706 DOI: 10.1109/tbme.2020.3033446] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE Noise reduction algorithms in current hearing devices lack informationabout the sound source a user attends to when multiple sources are present. To resolve this issue, they can be complemented with auditory attention decoding (AAD) algorithms, which decode the attention using electroencephalography (EEG) sensors. State-of-the-art AAD algorithms employ a stimulus reconstruction approach, in which the envelope of the attended source is reconstructed from the EEG and correlated with the envelopes of the individual sources. This approach, however, performs poorly on short signal segments, whilelonger segments yield impractically long detection delays when the user switches attention. METHODS We propose decoding the directional focus of attention using filterbank common spatial pattern filters (FB-CSP) as an alternative AAD paradigm, whichdoes not require access to the clean source envelopes. RESULTS The proposed FB-CSP approach outperforms both the stimulus reconstruction approach on short signal segments, as well as a convolutional neural network approach on the same task. We achieve a high accuracy (80% for [Formula: see text] windows and 70% for quasi-instantaneous decisions), which is sufficient to reach minimal expected switch durations below [Formula: see text]. We also demonstrate that the decoder can adapt to unlabeled data from anunseen subject and works with only a subset of EEG channels located around the ear to emulate a wearable EEG setup. CONCLUSION The proposed FB-CSP method provides fast and accurate decoding of the directional focus of auditory attention. SIGNIFICANCE The high accuracy on very short data segments is a major step forward towards practical neuro-steered hearing devices.
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Villa A, Mundanad Narayanan A, Van Huffel S, Bertrand A, Varon C. Utility metric for unsupervised feature selection. PeerJ Comput Sci 2021; 7:e477. [PMID: 33981839 PMCID: PMC8080425 DOI: 10.7717/peerj-cs.477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 03/16/2021] [Indexed: 06/12/2023]
Abstract
Feature selection techniques are very useful approaches for dimensionality reduction in data analysis. They provide interpretable results by reducing the dimensions of the data to a subset of the original set of features. When the data lack annotations, unsupervised feature selectors are required for their analysis. Several algorithms for this aim exist in the literature, but despite their large applicability, they can be very inaccessible or cumbersome to use, mainly due to the need for tuning non-intuitive parameters and the high computational demands. In this work, a publicly available ready-to-use unsupervised feature selector is proposed, with comparable results to the state-of-the-art at a much lower computational cost. The suggested approach belongs to the methods known as spectral feature selectors. These methods generally consist of two stages: manifold learning and subset selection. In the first stage, the underlying structures in the high-dimensional data are extracted, while in the second stage a subset of the features is selected to replicate these structures. This paper suggests two contributions to this field, related to each of the stages involved. In the manifold learning stage, the effect of non-linearities in the data is explored, making use of a radial basis function (RBF) kernel, for which an alternative solution for the estimation of the kernel parameter is presented for cases with high-dimensional data. Additionally, the use of a backwards greedy approach based on the least-squares utility metric for the subset selection stage is proposed. The combination of these new ingredients results in the utility metric for unsupervised feature selection U2FS algorithm. The proposed U2FS algorithm succeeds in selecting the correct features in a simulation environment. In addition, the performance of the method on benchmark datasets is comparable to the state-of-the-art, while requiring less computational time. Moreover, unlike the state-of-the-art, U2FS does not require any tuning of parameters.
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Affiliation(s)
- Amalia Villa
- STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, Department of Electrical Engineering (ESAT), KU Leuven, Leuven, Belgium
- Leuven.AI, KU Leuven Institute for AI, Leuven, Belgium
| | - Abhijith Mundanad Narayanan
- STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, Department of Electrical Engineering (ESAT), KU Leuven, Leuven, Belgium
- Leuven.AI, KU Leuven Institute for AI, Leuven, Belgium
| | - Sabine Van Huffel
- STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, Department of Electrical Engineering (ESAT), KU Leuven, Leuven, Belgium
- Leuven.AI, KU Leuven Institute for AI, Leuven, Belgium
| | - Alexander Bertrand
- STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, Department of Electrical Engineering (ESAT), KU Leuven, Leuven, Belgium
- Leuven.AI, KU Leuven Institute for AI, Leuven, Belgium
| | - Carolina Varon
- STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, Department of Electrical Engineering (ESAT), KU Leuven, Leuven, Belgium
- Circuits and Systems (CAS) Group, Delft University of Technology, Delft, The Netherlands
- e-Media Research Lab, Campus GroepT, KU Leuven, Leuven, Belgium
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Wouters J, Kloosterman F, Bertrand A. SHYBRID: A Graphical Tool for Generating Hybrid Ground-Truth Spiking Data for Evaluating Spike Sorting Performance. Neuroinformatics 2021; 19:141-158. [PMID: 32617751 DOI: 10.1007/s12021-020-09474-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Spike sorting is the process of retrieving the spike times of individual neurons that are present in an extracellular neural recording. Over the last decades, many spike sorting algorithms have been published. In an effort to guide a user towards a specific spike sorting algorithm, given a specific recording setting (i.e., brain region and recording device), we provide an open-source graphical tool for the generation of hybrid ground-truth data in Python. Hybrid ground-truth data is a data-driven modelling paradigm in which spikes from a single unit are moved to a different location on the recording probe, thereby generating a virtual unit of which the spike times are known. The tool enables a user to efficiently generate hybrid ground-truth datasets and make informed decisions between spike sorting algorithms, fine-tune the algorithm parameters towards the used recording setting, or get a deeper understanding of those algorithms.
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Affiliation(s)
- Jasper Wouters
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing, and Data Analytics, KU Leuven, Leuven, Belgium.
| | - Fabian Kloosterman
- Neuro-Electronics Research Flanders (NERF), Leuven, Belgium
- Brain & Cognition Research Unit, KU Leuven, Leuven, Belgium
- VIB, Leuven, Belgium
| | - Alexander Bertrand
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing, and Data Analytics, KU Leuven, Leuven, Belgium
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Heymans SV, Carlier B, Toumia Y, Nooijens S, Ingram M, Giammanco A, d'Agostino E, Crijns W, Bertrand A, Paradossi G, Himmelreich U, D'hooge J, Sterpin E, Van Den Abeele K. Modulating ultrasound contrast generation from injectable nanodroplets for proton range verification by varying the degree of superheat. Med Phys 2021; 48:1983-1995. [PMID: 33587754 DOI: 10.1002/mp.14778] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 01/21/2021] [Accepted: 02/08/2021] [Indexed: 12/25/2022] Open
Abstract
PURPOSE Despite the physical benefits of protons over conventional photon radiation in cancer treatment, range uncertainties impede the ability to harness the full potential of proton therapy. While monitoring the proton range in vivo could reduce the currently adopted safety margins, a routinely applicable range verification technique is still lacking. Recently, phase-change nanodroplets were proposed for proton range verification, demonstrating a reproducible relationship between the proton range and generated ultrasound contrast after radiation-induced vaporization at 25°C. In this study, previous findings are extended with proton irradiations at different temperatures, including the physiological temperature of 37°C, for a novel nanodroplet formulation. Moreover, the potential to modulate the linear energy transfer (LET) threshold for vaporization by varying the degree of superheat is investigated, where the aim is to demonstrate vaporization of nanodroplets directly by primary protons. METHODS Perfluorobutane nanodroplets with a shell made of polyvinyl alcohol (PVA-PFB) or 10,12-pentacosadyinoic acid (PCDA-PFB) were dispersed in polyacrylamide hydrogels and irradiated with 62 MeV passively scattered protons at temperatures of 37°C and 50°C. Nanodroplet transition into echogenic microbubbles was assessed using ultrasound imaging (gray value and attenuation analysis) and optical images. The proton range was measured independently and compared to the generated contrast. RESULTS Nanodroplet design proved crucial to ensure thermal stability, as PVA-shelled nanodroplets dramatically outperformed their PCDA-shelled counterpart. At body temperature, a uniform radiation response proximal to the Bragg peak is attributed to nuclear reaction products interacting with PVA-PFB nanodroplets, with the 50% drop in ultrasound contrast being 0.17 mm ± 0.20 mm (mean ± standard deviation) in front of the proton range. Also at 50°C, highly reproducible ultrasound contrast profiles were obtained with shifts of -0.74 mm ± 0.09 mm (gray value analysis), -0.86 mm ± 0.04 mm (attenuation analysis) and -0.64 mm ± 0.29 mm (optical analysis). Moreover, a strong contrast enhancement was observed near the Bragg peak, suggesting that nanodroplets were sensitive to primary protons. CONCLUSIONS By varying the degree of superheat of the nanodroplets' core, one can modulate the intensity of the generated ultrasound contrast. Moreover, a submillimeter reproducible relationship between the ultrasound contrast and the proton range was obtained, either indirectly via the visualization of secondary reaction products or directly through the detection of primary protons, depending on the degree of superheat. The potential of PVA-PFB nanodroplets for in vivo proton range verification was confirmed by observing a reproducible radiation response at physiological temperature, and further studies aim to assess the nanodroplets' performance in a physiological environment. Ultimately, cost-effective online or offline ultrasound imaging of radiation-induced nanodroplet vaporization could facilitate the reduction of safety margins in treatment planning and enable adaptive proton therapy.
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Affiliation(s)
- Sophie V Heymans
- Department of Physics, KU Leuven Campus Kulak, Kortrijk, Belgium
| | - Bram Carlier
- Department of Oncology, KU Leuven, Leuven, Belgium.,Molecular Small Animal Imaging Center, KU Leuven, Leuven, Belgium
| | - Yosra Toumia
- Department of Chemical Sciences and Technology, University of Rome Tor Vergata, Rome, Italy
| | - Sjoerd Nooijens
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Marcus Ingram
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | | | | | | | | | - Gaio Paradossi
- Department of Chemical Sciences and Technology, University of Rome Tor Vergata, Rome, Italy
| | - Uwe Himmelreich
- Molecular Small Animal Imaging Center, KU Leuven, Leuven, Belgium.,Department of Imaging & Pathology, KU Leuven, Leuven, Belgium
| | - Jan D'hooge
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
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Narayanan AM, Patrinos P, Bertrand A. Optimal Versus Approximate Channel Selection Methods for EEG Decoding With Application to Topology-Constrained Neuro-Sensor Networks. IEEE Trans Neural Syst Rehabil Eng 2020; 29:92-102. [PMID: 33141674 DOI: 10.1109/tnsre.2020.3035499] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Channel selection or electrode placement for neural decoding is a commonly encountered problem in electroencephalography (EEG). Since evaluating all possible channel combinations is usually infeasible, one usually has to settle for heuristic methods or convex approximations without optimality guarantees. To date, it remains unclear how large the gap is between the selection made by these approximate methods and the truly optimal selection. The goal of this paper is to quantify this optimality gap for several state-of-the-art channel selection methods in the context of least-squares based neural decoding. To this end, we reformulate the channel selection problem as a mixed-integer quadratic program (MIQP), which allows the use of efficient MIQP solvers to find the optimal channel combination in a feasible computation time for up to 100 candidate channels. As this reveals the exact solution to the combinatorial problem, it allows to quantify the performance losses when using state-of-the-art sub-optimal (yet faster) channel selection methods. In a context of auditory attention decoding, we find that a greedy channel selection based on the utility metric does not show a significant optimality gap compared to optimal channel selection, whereas other state-of-the-art greedy or l1 -norm penalized methods do show a significant loss in performance. Furthermore, we demonstrate that the MIQP formulation also provides a natural way to incorporate topology constraints in the selection, e.g., for electrode placement in neuro-sensor networks with galvanic separation constraints. Furthermore, a combination of this utility-based greedy selection with an MIQP solver allows to perform a topology constrained electrode placement, even in large scale problems with more than 100 candidate positions.
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Georges JL, Cochet H, Roger G, Ben Jemaa H, Soltani J, Azowa JB, Mamou R, Gilles F, Saba J, Prevot A, Pasqualini M, Monguillon V, De Tournemire M, Bertrand A, Koukabi-Fradelizi M, Beressi JP, Livarek B. [Association of hypertension and antihypertensive agents and the severity of COVID-19 pneumonia. A monocentric French prospective study]. Ann Cardiol Angeiol (Paris) 2020; 69:247-254. [PMID: 33039120 PMCID: PMC7522617 DOI: 10.1016/j.ancard.2020.09.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 09/18/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIM Angiotensin converting enzyme (ACE) type 2 is the receptor of SARSCoV-2 for cell entry into lung cells. Because ACE-2 may be modulated by ACE inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs), there are concern that patients treated with ACEIs and ARBs are at higher risk for COVID-19 infection or severity. This study sought to analyse the association of severe forms of COVID-19 and mortality with hypertension and a previous treatment with ACEI and ARB. METHODS Prospective follow-up of 433 consecutive patients hospitalised for COVID-19 pneumonia confirmed by PCR or highly probable on clinical, biological, and radiological findings, and included in the COVHYP study. Mortality and severe COVID-19 (criteria: death, intensive care unit, or hospitalisation >30 days) were compared in patients receiving or not ACEIs and ARBs. Follow-up was 100% at hospital discharge, and 96.5% at >1month. RESULTS Age was 63.6±18.7 years, and 40%) were female. At follow-up (mean 78±50 days), 136 (31%) patients had severity criteria (death, 64 ; intensive care unit, 73; hospital stay >30 days, 49). Hypertension (55.1% vs 36.7%, P<0.001) and antihypertensive treatment were associated with severe COVID-19 and mortality. The association between ACEI/ARB treatment and COVID-19 severity criteria found in univariate analysis (Odds Ratio 1.74, 95%CI [1.14-2.64], P=0.01) was not confirmed when adjusted on age, gender, and hypertension (adjusted OR1.13 [0.59-2.15], P=0.72). Diabetes and hypothyroidism were associated with severe COVID-19, whereas history of asthma was not. CONCLUSION This study suggests that previous treatment with ACEI and ARB is not associated with hospital mortality, 1- and 2-month mortality, and severity criteria in patients hospitalised for COVID-19. No protective effect of ACEIs and ARBs on severe pneumonia related to COVID-19 was demonstrated.
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Affiliation(s)
- J-L Georges
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France.
| | - H Cochet
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - G Roger
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - H Ben Jemaa
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - J Soltani
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - J-B Azowa
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - R Mamou
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - F Gilles
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - J Saba
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - A Prevot
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - M Pasqualini
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - V Monguillon
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - M De Tournemire
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - A Bertrand
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - M Koukabi-Fradelizi
- Service d'accueil des urgences, Centre Hospitalier de Versailles, Le Chesnay, France
| | - J-P Beressi
- Service de diabétologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - B Livarek
- Service de cardiologie, Centre Hospitalier de Versailles, Le Chesnay, France
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Das N, Zegers J, Van hamme H, Francart T, Bertrand A. Linear versus deep learning methods for noisy speech separation for EEG-informed attention decoding. J Neural Eng 2020; 17:046039. [DOI: 10.1088/1741-2552/aba6f8] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Dan J, Vandendriessche B, Paesschen WV, Weckhuysen D, Bertrand A. Computationally-Efficient Algorithm for Real-Time Absence Seizure Detection in Wearable Electroencephalography. Int J Neural Syst 2020; 30:2050035. [PMID: 32808854 DOI: 10.1142/s0129065720500355] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Advances in electroencephalography (EEG) equipment now allow monitoring of people with epilepsy in their daily-life environment. The large volumes of data that can be collected from long-term out-of-clinic monitoring require novel algorithms to process the recordings on board of the device to identify and log or transmit only relevant data epochs. Existing seizure-detection algorithms are generally designed for post-processing purposes, so that memory and computing power are rarely considered as constraints. We propose a novel multi-channel EEG signal processing method for automated absence seizure detection which is specifically designed to run on a microcontroller with minimal memory and processing power. It is based on a linear multi-channel filter that is precomputed offline in a data-driven fashion based on the spatial-temporal signature of the seizure and peak interference statistics. At run-time, the algorithm requires only standard linear filtering operations, which are cheap and efficient to compute, in particular on microcontrollers with a multiply-accumulate unit (MAC). For validation, a dataset of eight patients with juvenile absence epilepsy was collected. Patients were equipped with a 20-channel mobile EEG unit and discharged for a day-long recording. The algorithm achieves a median of 0.5 false detections per day at 95% sensitivity. We compare our algorithm with state-of-the-art absence seizure detection algorithms and conclude it performs on par with these at a much lower computational cost.
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Affiliation(s)
- Jonathan Dan
- STADIUS - ESAT KU Leuven, Leuven, Belgium.,Byteflies, Antwerp, Belgium
| | | | - Wim Van Paesschen
- Neurology - UZ Leuven, Leuven, Belgium.,Department of Neurology - KU Leuven, Leuven, Belgium
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Rigalleau V, Bertrand A, Rojubally S, Majchrzak C, Bocock O, Foussard N, Monlun M, Blanco L, Mohammedi K. Continuous subcutaneous insulin infusion and neuropathy in older people. Diabet Med 2020; 37:1208-1209. [PMID: 32276296 DOI: 10.1111/dme.14302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/01/2020] [Indexed: 11/30/2022]
Affiliation(s)
- V Rigalleau
- Endocrinology-Nutrition Department, Centre Hospitalier Universitaire de Bordeaux, France
| | - A Bertrand
- Endocrinology-Nutrition Department, Centre Hospitalier Universitaire de Bordeaux, France
| | - S Rojubally
- Endocrinology-Nutrition Department, Centre Hospitalier Universitaire de Bordeaux, France
| | - C Majchrzak
- Endocrinology-Nutrition Department, Centre Hospitalier Universitaire de Bordeaux, France
| | - O Bocock
- Endocrinology-Nutrition Department, Centre Hospitalier Universitaire de Bordeaux, France
| | - N Foussard
- Endocrinology-Nutrition Department, Centre Hospitalier Universitaire de Bordeaux, France
| | - M Monlun
- Endocrinology-Nutrition Department, Centre Hospitalier Universitaire de Bordeaux, France
| | - L Blanco
- Endocrinology-Nutrition Department, Centre Hospitalier Universitaire de Bordeaux, France
| | - K Mohammedi
- Endocrinology-Nutrition Department, Centre Hospitalier Universitaire de Bordeaux, France
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33
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Bertrand A, Paraschiv C. Les régimes protégés en Auvergne Rhône-Alpes, si on en parlait ? NUTR CLIN METAB 2020. [DOI: 10.1016/j.nupar.2020.02.385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Das N, Vanthornhout J, Francart T, Bertrand A. Stimulus-aware spatial filtering for single-trial neural response and temporal response function estimation in high-density EEG with applications in auditory research. Neuroimage 2020; 204:116211. [PMID: 31546052 PMCID: PMC7355237 DOI: 10.1016/j.neuroimage.2019.116211] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 08/30/2019] [Accepted: 09/17/2019] [Indexed: 12/21/2022] Open
Abstract
A common problem in neural recordings is the low signal-to-noise ratio (SNR), particularly when using non-invasive techniques like magneto- or electroencephalography (M/EEG). To address this problem, experimental designs often include repeated trials, which are then averaged to improve the SNR or to infer statistics that can be used in the design of a denoising spatial filter. However, collecting enough repeated trials is often impractical and even impossible in some paradigms, while analyses on existing data sets may be hampered when these do not contain such repeated trials. Therefore, we present a data-driven method that takes advantage of the knowledge of the presented stimulus, to achieve a joint noise reduction and dimensionality reduction without the need for repeated trials. The method first estimates the stimulus-driven neural response using the given stimulus, which is then used to find a set of spatial filters that maximize the SNR based on a generalized eigenvalue decomposition. As the method is fully data-driven, the dimensionality reduction enables researchers to perform their analyses without having to rely on their knowledge of brain regions of interest, which increases accuracy and reduces the human factor in the results. In the context of neural tracking of a speech stimulus using EEG, our method resulted in more accurate short-term temporal response function (TRF) estimates, higher correlations between predicted and actual neural responses, and higher attention decoding accuracies compared to existing TRF-based decoding methods. We also provide an extensive discussion on the central role played by the generalized eigenvalue decomposition in various denoising methods in the literature, and address the conceptual similarities and differences with our proposed method.
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Affiliation(s)
- Neetha Das
- Dept. Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Kasteelpark Arenberg 10, B-3001, Leuven, Belgium; Dept. Neurosciences, ExpORL, KU Leuven, Herestraat 49 Bus 721, B-3000, Leuven, Belgium.
| | - Jonas Vanthornhout
- Dept. Neurosciences, ExpORL, KU Leuven, Herestraat 49 Bus 721, B-3000, Leuven, Belgium
| | - Tom Francart
- Dept. Neurosciences, ExpORL, KU Leuven, Herestraat 49 Bus 721, B-3000, Leuven, Belgium
| | - Alexander Bertrand
- Dept. Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Kasteelpark Arenberg 10, B-3001, Leuven, Belgium.
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Geirnaert S, Francart T, Bertrand A. An Interpretable Performance Metric for Auditory Attention Decoding Algorithms in a Context of Neuro-Steered Gain Control. IEEE Trans Neural Syst Rehabil Eng 2019; 28:307-317. [PMID: 31715568 DOI: 10.1109/tnsre.2019.2952724] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In a multi-speaker scenario, a hearing aid lacks information on which speaker the user intends to attend, and therefore it often mistakenly treats the latter as noise while enhancing an interfering speaker. Recently, it has been shown that it is possible to decode the attended speaker from the brain activity, e.g., recorded by electroencephalography sensors. While numerous of these auditory attention decoding (AAD) algorithms appeared in the literature, their performance is generally evaluated in a non-uniform manner. Furthermore, AAD algorithms typically introduce a trade-off between the AAD accuracy and the time needed to make an AAD decision, which hampers an objective benchmarking as it remains unclear which point in each algorithm's trade-off space is the optimal one in a context of neuro-steered gain control. To this end, we present an interpretable performance metric to evaluate AAD algorithms, based on an adaptive gain control system, steered by AAD decisions. Such a system can be modeled as a Markov chain, from which the minimal expected switch duration (MESD) can be calculated and interpreted as the expected time required to switch the operation of the hearing aid after an attention switch of the user, thereby resolving the trade-off between AAD accuracy and decision time. Furthermore, we show that the MESD calculation provides an automatic and theoretically founded procedure to optimize the number of gain levels and decision time in an AAD-based adaptive gain control system.
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Wouters J, Kloosterman F, Bertrand A. A data-driven regularization approach for template matching in spike sorting with high-density neural probes. Annu Int Conf IEEE Eng Med Biol Soc 2019; 2019:4376-4379. [PMID: 31946837 DOI: 10.1109/embc.2019.8856930] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Spike sorting is the process of assigning neural spikes in an extracellular brain recording to their putative neurons. Optimal pre-whitened template matching filters that are used in spike sorting typically suffer from ill-conditioning. In this paper, we investigate the origin of this ill-conditioning and the way in which it influences the resulting filters. Two data-driven subspace regularization approaches are proposed, and those are shown to outperform a regularization approach used in recent literature. The comparison of the methods is based on ground truth data that are recorded in-vivo.
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Narayanan AM, Bertrand A. Analysis of Miniaturization Effects and Channel Selection Strategies for EEG Sensor Networks With Application to Auditory Attention Detection. IEEE Trans Biomed Eng 2019; 67:234-244. [PMID: 30998455 DOI: 10.1109/tbme.2019.2911728] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Concealable, miniaturized electroencephalography (mini-EEG) recording devices are crucial enablers toward long-term ambulatory EEG monitoring. However, the resulting miniaturization limits the inter-electrode distance and the scalp area that can be covered by a single device. The concept of wireless EEG sensor networks (WESNs) attempts to overcome this limitation by placing a multitude of these mini-EEG devices at various scalp locations. We investigate whether optimizing the WESN topology can compensate for miniaturization effects in an auditory attention detection (AAD) paradigm. METHODS Starting from standard full-cap high-density EEG data, we emulate several candidate mini-EEG sensor nodes that locally collect EEG data with embedded electrodes separated by short distances. We propose a greedy group-utility based channel selection strategy to select a subset of these candidate nodes to form a WESN. We compare the AAD performance of this WESN with the performance obtained using long-distance EEG recordings. RESULTS The AAD performance using short-distance EEG measurements is comparable to using an equal number of long-distance EEG measurements if, in both cases, the optimal electrode positions are selected. A significant increase in performance was found when using nodes with three electrodes over nodes with two electrodes. CONCLUSION When the nodes are optimally placed, WESNs do not significantly suffer from EEG miniaturization effects in the case of AAD. SIGNIFICANCE WESN-like platforms allow us to achieve similar AAD performance as with long-distance EEG recordings while adhering to the stringent miniaturization constraints for ambulatory EEG. Their applicability in an AAD task is important for the design of neuro-steered auditory prostheses.
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Abstract
OBJECTIVE A listener's neural responses can be decoded to identify the speaker the person is attending to in a cocktail party environment. Such auditory attention detection methods have the potential to provide noise suppression algorithms in hearing devices with information about the listener's attention. A challenge is the effect of noise and other acoustic conditions that can reduce the attention detection accuracy. Specifically, noise can impact the ability of the person to segregate the sound sources and perform selective attention, as well as the external signal processing necessary to decode the attention effectively. The aim of this work is to systematically analyze the effect of noise level and speaker position on attention decoding accuracy. APPROACH 28 subjects participated in the experiment. Auditory stimuli consisted of stories narrated by different speakers from two different locations, along with surrounding multi-talker background babble. EEG signals of the subjects were recorded while they focused on one story and ignored the other. The strength of the babble noise as well as the spatial separation between the two speakers were varied between presentations. Spatio-temporal decoders were trained for each subject, and applied to decode attention of the subjects from every 30 s segment of data. Behavioral speech recognition thresholds were obtained for the different speaker separations. MAIN RESULTS Both the background noise level and the angular separation between speakers affected attention decoding accuracy. Remarkably, attention decoding performance was seen to increase with the inclusion of moderate background noise (versus no noise), while across the different noise conditions performance dropped significantly with increasing noise level. We also observed that decoding accuracy improved with increasing speaker separation, exhibiting the advantage of spatial release from masking. Furthermore, the effect of speaker separation on the decoding accuracy became stronger when the background noise level increased. A significant correlation between speech intelligibility and attention decoding accuracy was found across conditions. SIGNIFICANCE This work shows how the background noise level and relative positions of competing talkers impact attention decoding accuracy. It indicates in which circumstances a neuro-steered noise suppression system may need to operate, in function of acoustic conditions. It also indicates the boundary conditions for the operation of EEG-based attention detection systems in neuro-steered hearing prostheses.
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Affiliation(s)
- Neetha Das
- Department of Electrical Engineering (ESAT), Stadius Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium. Department of Neurosciences, ExpORL, KU Leuven, Herestraat 49 bus 721, B-3000 Leuven, Belgium
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Wouters J, Kloosterman F, Bertrand A. Towards online spike sorting for high-density neural probes using discriminative template matching with suppression of interfering spikes. J Neural Eng 2018; 15:056005. [DOI: 10.1088/1741-2552/aace8a] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kil D, De Vloo P, Fierens G, Ceyssens F, Hunyadi B, Bertrand A, Nuttin B, Puers R. A foldable electrode array for 3D recording of deep-seated abnormal brain cavities. J Neural Eng 2018; 15:036029. [PMID: 29569571 DOI: 10.1088/1741-2552/aab915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE This study describes the design and microfabrication of a foldable thin-film neural implant and investigates its suitability for electrical recording of deep-lying brain cavity walls. APPROACH A new type of foldable neural electrode array is presented, which can be inserted through a cannula. The microfabricated electrode is specifically designed for electrical recording of the cavity wall of thalamic lesions resulting from stroke. The proof-of-concept is demonstrated by measurements in rat brain cavities. On implantation, the electrode array unfolds in the brain cavity, contacting the cavity walls and allowing recording at multiple anatomical locations. A three-layer microfabrication process based on UV-lithography and Reactive Ion Etching is described. Electrochemical characterization of the electrode is performed in addition to an in vivo experiment in which the implantation procedure and the unfolding of the electrode are tested and visualized. MAIN RESULTS Electrochemical characterization validated the suitability of the electrode for in vivo use. CT imaging confirmed the unfolding of the electrode in the brain cavity and analysis of recorded local field potentials showed the ability to record neural signals of biological origin. SIGNIFICANCE The conducted research confirms that it is possible to record neural activity from the inside wall of brain cavities at various anatomical locations after a single implantation procedure. This opens up possibilities towards research of abnormal brain cavities and the clinical conditions associated with them, such as central post-stroke pain.
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Affiliation(s)
- Dries Kil
- Department of ESAT-MICAS, KU Leuven, Leuven, Belgium
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Bertrand A, Rondenet C, Masliah-Planchon J, Leblond P, de la Fourchardière A, Pissaloux D, Aït-Raïs K, Lequin D, Jouvet A, Freneaux P, Sevestre H, Ranchere-Vince D, Tauziede-Espariat A, Maurage CA, Silva K, Pierron G, Delattre O, Varlet P, Frappaz D, Bourdeaut F. Rhabdoid component emerging as a subclonal evolution of paediatric glioneuronal tumours. Neuropathol Appl Neurobiol 2018; 44:224-228. [DOI: 10.1111/nan.12379] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 11/28/2016] [Accepted: 12/23/2016] [Indexed: 10/20/2022]
Affiliation(s)
- A. Bertrand
- Pediatric Oncology Unit; Centre Leon Berard; Lyon France
| | - C. Rondenet
- Department of Neuropathology; Sainte-Anne Hospital; Paris France
| | - J. Masliah-Planchon
- Institut Curie; Somatic Genetics Unit; Paris France
- Cancer Genetics and Biology Laboratory; Institut Curie; INSERM U830; Paris France
| | - P. Leblond
- Pediatric Oncology Unit; Centre Oscar Lambret; Lille France
| | | | - D. Pissaloux
- Biopathology Unit; Centre Leon Berard; Lyon France
| | - K. Aït-Raïs
- Institut Curie; Somatic Genetics Unit; Paris France
| | - D. Lequin
- Institut Curie; Somatic Genetics Unit; Paris France
| | - A. Jouvet
- Department of Neuropathology; Groupement Hospitalier Est; Bron France
| | - P. Freneaux
- Department of Pathology; Institut Curie; Paris France
| | - H. Sevestre
- Neuropathology; University Hospital; Amiens France
| | | | | | - C.-A. Maurage
- Department of Neuropathology; Lille University Hospital; Lille France
| | - K. Silva
- Department of Neuropathology; Groupement Hospitalier Est; Bron France
| | - G. Pierron
- Institut Curie; Somatic Genetics Unit; Paris France
| | - O. Delattre
- Cancer Genetics and Biology Laboratory; Institut Curie; INSERM U830; Paris France
| | - P. Varlet
- Department of Neuropathology; Sainte-Anne Hospital; Paris France
| | - D. Frappaz
- Pediatric Oncology Unit; Centre Leon Berard; Lyon France
| | - F. Bourdeaut
- Cancer Genetics and Biology Laboratory; Institut Curie; INSERM U830; Paris France
- Pediatric Oncology Translational Research Laboratory; SiRIC Institut Curie; Paris France
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Ariane M, Leroux G, Bertrand A, Jaureguiberry S, Saadoun D, Mazier D, Caumes E, Cacoub P. Des lésions cérébrales. Rev Med Interne 2018; 39:68-70. [DOI: 10.1016/j.revmed.2016.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 04/09/2016] [Indexed: 11/30/2022]
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Négrier C, Ducloy-Bouthors AS, Piriou V, De Maistre E, Stieltjes N, Borel-Derlon A, Colson P, Picard J, Lambert T, Claeyssens S, Boileau S, Bertrand A, André MH, Fourrier F, Ozier Y, Sié P, Gruel Y, Tellier Z. Postauthorization safety study of Clottafact®
, a triply secured fibrinogen concentrate in acquired fibrinogen deficiency: a prospective observational study. Vox Sang 2017; 113:120-127. [DOI: 10.1111/vox.12624] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 09/26/2017] [Accepted: 11/14/2017] [Indexed: 01/02/2023]
Affiliation(s)
| | | | - V. Piriou
- South University Hospital; Lyon France
| | | | | | | | - P. Colson
- University Hospital; Montpellier France
| | - J. Picard
- University Hospital; Grenoble France
| | - T. Lambert
- Bicêtre Hospital; Kremlin Bicêtre France
| | | | | | - A. Bertrand
- Medical Affairs; LFB Biomédicaments; Les Ulis France
| | - M.-H. André
- Medical Affairs; LFB Biomédicaments; Les Ulis France
| | | | - Y. Ozier
- University Hospital; Brest France
| | - P. Sié
- Rangueil Hospital; Toulouse France
| | - Y. Gruel
- Trousseau Hospital; Tours France
| | - Z. Tellier
- Medical Affairs; LFB Biomédicaments; Les Ulis France
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Haumonte JB, Raylet M, Christophe M, Mauviel F, Bertrand A, Desbriere R, d'Ercole C. French validation and adaptation of the Grobman nomogram for prediction of vaginal birth after cesarean delivery. J Gynecol Obstet Hum Reprod 2017; 47:127-131. [PMID: 29229362 DOI: 10.1016/j.jogoh.2017.12.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 12/03/2017] [Accepted: 12/04/2017] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To validate Grobman nomogram for predicting vaginal birth after cesarean delivery (VBAC) in a French population and adapt it. STUDY DESIGN Multicenter retrospective study of maternal and obstetric factors associated with VBAC between May 2012 and May 2013 in 6 maternity units. External validation and adaptation of the prenatal and intrapartum Grobman nomograms for vaginal birth prediction after cesarean delivery in a French cohort. RESULTS The study included 523 women with previous cesarean deliveries; 70% underwent a trial of labor for a subsequent delivery (n=367) with a success rate of 65% (n=240). In the univariate analysis, 5 factors were associated with successful VBAC: previous vaginal delivery before the cesarean (P<0.001), the number of previous vaginal deliveries (P<0.001), and a favorable cervix at delivery room admission, cervical effacement (P=0.035), or cervical dilatation at least 3cm (P<0.001), or a Bishop score >6 (P=0.03). A potentially recurrent indication (defined as arrest of dilation or descent as the indication for the previous cesarean) (P=0.039), a hypertensive disorder during pregnancy (P=0.05), and labor induction (P=0.017) were each associated with failed VBAC. External validation of the prenatal and intrapartum Grobman nomograms showed an area under the ROC curve of 69% (95% CI: 0.638, 0.736) and 65% (95% CI: 0.599, 0.700) respectively. Adaptation of the nomogram to the French cohort resulted in the inclusion of the following factors: maternal age, body mass index at last prenatal visit, hypertensive disorder, gestational age at delivery, recurring indication, cervical dilatation, and induction of labor. Its area under the curve to predict successful VBAC was 78% (95% CI: 0.738, 0.825). CONCLUSION The nomogram to predict VBAC developed by Grobman et al. is validated in the French population. Adaptation to the French population, by excluding ethnicity, appeared to improve its performance. Impact of the nomogram use on the caesarean section rate has to be validated in a randomized control trial.
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Affiliation(s)
- J-B Haumonte
- Obstetrics and Gynaecology unit, Hospital Saint-Joseph, 13285 Marseille, France; Hôpital Nord, Assistance publique-hôpitaux de Marseille, 13015 Marseille, France.
| | - M Raylet
- Obstetrics and Gynaecology unit, centre hospitalier du Pays d'Aix, 13616 Aix-en-Provence, France
| | - M Christophe
- Obstetrics and Gynaecology unit, CHG de Martigues, 13500 Martigues, France
| | - F Mauviel
- Obstetrics and Gynaecology unit, CHIC de Toulon-La-Seyne, 83100 Toulon-La-Seyne, France
| | - A Bertrand
- Obstetrics and Gynaecology unit, CHG de Salon-de-Provence, 13300 Salon-de-Provence, France
| | - R Desbriere
- Obstetrics and Gynaecology unit, Hospital Saint-Joseph, 13285 Marseille, France
| | - C d'Ercole
- Obstetrics and Gynaecology unit, hôpital Conception, Assistance publique-hôpitaux de Marseille, 13005 Marseille, France
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Fernández-Fuego D, Bertrand A, González A. Metal accumulation and detoxification mechanisms in mycorrhizal Betula pubescens. Environ Pollut 2017; 231:1153-1162. [PMID: 28941719 DOI: 10.1016/j.envpol.2017.07.072] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/19/2017] [Accepted: 07/22/2017] [Indexed: 06/07/2023]
Abstract
Metal detoxification in plants is a complex process that involves different mechanisms, such as the retention of metals to the cell wall and their chelation and subsequent compartmentalization in plant vacuoles. In order to identify the mechanisms involved in metal accumulation and tolerance in Betula pubescens, as well as the role of mycorrhization in these processes, mycorrhizal and non-mycorrhizal plants were grown in two industrial soils with contrasting concentrations of heavy metals. Mycorrhization increased metal uptake at low metal concentrations in the soil and reduced it at high metal concentrations, which led to an enhanced growth and biomass production of the host when growing in the most polluted soil. Our results suggest that the sequestration on the cell wall is the main detoxification mechanism in white birch exposed to acute chronic metal-stress, while phytochelatins play a role mitigating metal toxicity inside the cells. Given its high Mn and Zn root-to-shoot translocation rate, Betula pubescens is a very promising species for the phytoremediation of soils polluted with these metals.
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Affiliation(s)
- D Fernández-Fuego
- Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, Catedrático Rodrigo Uría s/n, 33071 Oviedo, Spain; Instituto Universitario de Biotecnología de Asturias, Spain
| | - A Bertrand
- Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, Catedrático Rodrigo Uría s/n, 33071 Oviedo, Spain; Instituto Universitario de Biotecnología de Asturias, Spain
| | - A González
- Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, Catedrático Rodrigo Uría s/n, 33071 Oviedo, Spain; Instituto Universitario de Biotecnología de Asturias, Spain.
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Guédron S, Point D, Acha D, Bouchet S, Baya PA, Tessier E, Monperrus M, Molina CI, Groleau A, Chauvaud L, Thebault J, Amice E, Alanoca L, Duwig C, Uzu G, Lazzaro X, Bertrand A, Bertrand S, Barbraud C, Delord K, Gibon FM, Ibanez C, Flores M, Fernandez Saavedra P, Ezpinoza ME, Heredia C, Rocha F, Zepita C, Amouroux D. Mercury contamination level and speciation inventory in Lakes Titicaca & Uru-Uru (Bolivia): Current status and future trends. Environ Pollut 2017; 231:262-270. [PMID: 28806691 DOI: 10.1016/j.envpol.2017.08.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/27/2017] [Accepted: 08/02/2017] [Indexed: 06/07/2023]
Abstract
Aquatic ecosystems of the Bolivian Altiplano (∼3800 m a.s.l.) are characterized by extreme hydro-climatic constrains (e.g., high UV-radiations and low oxygen) and are under the pressure of increasing anthropogenic activities, unregulated mining, agricultural and urban development. We report here a complete inventory of mercury (Hg) levels and speciation in the water column, atmosphere, sediment and key sentinel organisms (i.e., plankton, fish and birds) of two endorheic Lakes of the same watershed differing with respect to their size, eutrophication and contamination levels. Total Hg (THg) and monomethylmercury (MMHg) concentrations in filtered water and sediment of Lake Titicaca are in the lowest range of reported levels in other large lakes worldwide. Downstream, Hg levels are 3-10 times higher in the shallow eutrophic Lake Uru-Uru than in Lake Titicaca due to high Hg inputs from the surrounding mining region. High percentages of MMHg were found in the filtered and unfiltered water rising up from <1 to ∼50% THg from the oligo/hetero-trophic Lake Titicaca to the eutrophic Lake Uru-Uru. Such high %MMHg is explained by a high in situ MMHg production in relation to the sulfate rich substrate, the low oxygen levels of the water column, and the stabilization of MMHg due to abundant ligands present in these alkaline waters. Differences in MMHg concentrations in water and sediments compartments between Lake Titicaca and Uru-Uru were found to mirror the offset in MMHg levels that also exist in their respective food webs. This suggests that in situ MMHg baseline production is likely the main factor controlling MMHg levels in fish species consumed by the local population. Finally, the increase of anthropogenic pressure in Lake Titicaca may probably enhance eutrophication processes which favor MMHg production and thus accumulation in water and biota.
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Affiliation(s)
- S Guédron
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000 Grenoble, France; Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, Campus Universitario de Cota-Cota, Casilla 3161, La Paz, Bolivia.
| | - D Point
- Géosciences Environnement Toulouse, UMR5563 - IRD UR 234, Université Paul Sabatier, 14 Avenue Edouard Belin 31400 Toulouse, France; Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia.
| | - D Acha
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia.
| | - S Bouchet
- CNRS, Univ. Pau & Pays Adour, Institut des sciences analytiques et de Physico-chimie pour l'Environnement et les Matériaux, MIRA, UMR5254, 64000 PAU, France
| | - P A Baya
- Géosciences Environnement Toulouse, UMR5563 - IRD UR 234, Université Paul Sabatier, 14 Avenue Edouard Belin 31400 Toulouse, France
| | - E Tessier
- CNRS, Univ. Pau & Pays Adour, Institut des sciences analytiques et de Physico-chimie pour l'Environnement et les Matériaux, MIRA, UMR5254, 64000 PAU, France
| | - M Monperrus
- CNRS, Univ. Pau & Pays Adour, Institut des sciences analytiques et de Physico-chimie pour l'Environnement et les Matériaux, MIRA, UMR5254, 64000 PAU, France
| | - C I Molina
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - A Groleau
- Institut de Physique du Globe de Paris (IPGP), 1, rue Jussieu, 75238 Paris Cedex 05, France
| | - L Chauvaud
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539, IUEM Technopôle Brest-Iroise, rue Dumont d'Urville, 29280 Plouzané, France
| | - J Thebault
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539, IUEM Technopôle Brest-Iroise, rue Dumont d'Urville, 29280 Plouzané, France
| | - E Amice
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539, IUEM Technopôle Brest-Iroise, rue Dumont d'Urville, 29280 Plouzané, France
| | - L Alanoca
- Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, Campus Universitario de Cota-Cota, Casilla 3161, La Paz, Bolivia
| | - C Duwig
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, IGE, 38000 Grenoble, France
| | - G Uzu
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, IGE, 38000 Grenoble, France
| | - X Lazzaro
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia; Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Institut de Recherche pour le Développement (IRD), UMR 7208, Paris, France
| | - A Bertrand
- MARine Biodiversity, Exploitation and Conservation (MARBEC), Institut de Recherche pour le Développement (IRD), Univ. Montpellier, Place Eugène Bataillon, bât 24, CC093 34 095 Montpellier Cedex 5, France
| | - S Bertrand
- MARine Biodiversity, Exploitation and Conservation (MARBEC), Institut de Recherche pour le Développement (IRD), Univ. Montpellier, Place Eugène Bataillon, bât 24, CC093 34 095 Montpellier Cedex 5, France
| | - C Barbraud
- Laboratoire du Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372, CNRS, Université de La Rochelle 405 Route de La Canauderie, 79360 Villiers-en-Bois, France
| | - K Delord
- Laboratoire du Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372, CNRS, Université de La Rochelle 405 Route de La Canauderie, 79360 Villiers-en-Bois, France
| | - F M Gibon
- Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Institut de Recherche pour le Développement (IRD), UMR 7208, Paris, France
| | - C Ibanez
- UPA, Universidad Pública de El Alto, Ecología y Recursos Naturales, El Alto, Bolivia
| | - M Flores
- Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, Campus Universitario de Cota-Cota, Casilla 3161, La Paz, Bolivia; Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - P Fernandez Saavedra
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - M E Ezpinoza
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - C Heredia
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - F Rocha
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - C Zepita
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia
| | - D Amouroux
- Unidad de Calidad Ambiental (UCA), Instituto de Ecología, Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, Casilla 3161, La Paz, Bolivia; CNRS, Univ. Pau & Pays Adour, Institut des sciences analytiques et de Physico-chimie pour l'Environnement et les Matériaux, MIRA, UMR5254, 64000 PAU, France.
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Bertrand A, Legrand C, Léonard D, Van Keilegom I. Robustness of estimation methods in a survival cure model with mismeasured covariates. Comput Stat Data Anal 2017. [DOI: 10.1016/j.csda.2016.11.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Fernández-Fuego D, Keunen E, Cuypers A, Bertrand A, González A. Mycorrhization protects Betula pubescens Ehr. from metal-induced oxidative stress increasing its tolerance to grow in an industrial polluted soil. Journal of Hazardous Materials 2017; 336:119-127. [PMID: 28494299 DOI: 10.1016/j.jhazmat.2017.04.065] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 03/31/2017] [Accepted: 04/26/2017] [Indexed: 06/07/2023]
Abstract
In recent years, the use of woody plants in phytoremediation has gained popularity due to their high biomass production and their association with mycorrhizal fungi, which can improve their survival and development rates under stress conditions. In this study, mycorrhized and non-mycorrhized white birch plants (Betula pubescens Ehr.) were grown in control and a metal-polluted industrial soil. After 60days of culture, plant growth and metal accumulation, the content of photosynthetic pigments and oxidative-stress markers, as well as the enzymatic activities and gene expressions of antioxidant enzymes were measured. According to our results, mycorrhized birch plants grown in control soil showed an increased activity and gene expression of catalase and ascorbate peroxidase, along with hydrogen peroxide overproduction, which could support the importance of the reactive oxygen species as signaling molecules in the regulation of plant-fungus interactions. Additionally, in polluted soil mycorrhized plants had higher biomass but lower metal accumulation, probably because the symbiotic fungus acted as a barrier to the entrance of metals into the host plants. This behavior led to mitigation in the oxidative challenge, reduced hydrogen peroxide content and diminished activities of the antioxidant enzymes in comparison to non-mycorrhized plants.
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Affiliation(s)
- D Fernández-Fuego
- Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, Catedrático Rodrigo Uría s/n, 33071 Oviedo, Spain; Instituto Universitario de Biotecnología de Asturias, Spain
| | - E Keunen
- Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium
| | - A Cuypers
- Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium
| | - A Bertrand
- Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, Catedrático Rodrigo Uría s/n, 33071 Oviedo, Spain; Instituto Universitario de Biotecnología de Asturias, Spain
| | - A González
- Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, Catedrático Rodrigo Uría s/n, 33071 Oviedo, Spain; Instituto Universitario de Biotecnología de Asturias, Spain.
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Hainque E, Blancher A, Mesnage V, Rivaud-Pechoux S, Bertrand A, Dupont S, Navarro V, Roze E, Gourfinkel-An I, Apartis E. A clinical and neurophysiological motor signature of Unverricht-Lundborg disease. Rev Neurol (Paris) 2017; 174:56-65. [PMID: 28688606 DOI: 10.1016/j.neurol.2017.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 04/03/2017] [Accepted: 06/01/2017] [Indexed: 11/17/2022]
Abstract
OBJECTIVES Unverricht-Lundborg disease (ULD) is the most common form of progressive myoclonus epilepsy. Cerebellar dysfunction may appear over time, contributing along with myoclonus to motor disability. The purpose of the present work was to clarify the motor and neurophysiological characteristics of ULD patients. METHODS Nine patients with genetically proven ULD were evaluated clinically (medical history collected from patient charts, the Scale for the Assessment and Rating of Ataxia and Unified Myoclonus Rating Scale). Neurophysiological investigations included EEG, surface polymyography, long-loop C-reflexes, somatosensory evoked potentials, EEG jerk-locked back-averaging (JLBA) and oculomotor recordings. All patients underwent brain MRI. Non-parametric Mann-Whitney tests were used to compare ULD patients' oculomotor parameters with those of a matched group of healthy volunteers (HV). RESULTS Myoclonus was activated by action but was virtually absent at rest and poorly induced by stimuli. Positive myoclonus was multifocal, often rhythmic and of brief duration, with top-down pyramidal temporospatial propagation. Cortical neurophysiology revealed a transient wave preceding myoclonus on EEG JLBA (n=8), enlarged somatosensory evoked potentials (n=7) and positive long-loop C-reflexes at rest (n=5). Compared with HV, ULD patients demonstrated decreased saccadic gain, increased gain dispersion and a higher frequency of hypermetric saccades associated with decreased peak velocity. CONCLUSION A homogeneous motor pattern was delineated that may represent a ULD clinical and neurophysiological signature. Clinical and neurophysiological findings confirmed the pure cortical origin of the permanent myoclonus. Also, oculomotor findings shed new light on ULD pathophysiology by evidencing combined midbrain and cerebellar dysfunction.
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Affiliation(s)
- E Hainque
- Unité de neurophysiologie, département DéPAS, hôpital Saint-Antoine, AP-HP, 184, rue du Faubourg-Saint-Antoine, 75012 Paris, France; Inserm U1127, CNRS UMR7225, institut du cerveau et de la moelle épinière, ICM, Paris Sorbonne universités, UPMC, université de Paris 06, UMR S1127, 47, boulevard de l'hôpital, 75651 Paris cedex 13, France
| | - A Blancher
- Unité de neurophysiologie, département DéPAS, hôpital Saint-Antoine, AP-HP, 184, rue du Faubourg-Saint-Antoine, 75012 Paris, France
| | - V Mesnage
- Service de neurologie, hôpital Saint-Antoine, AP-HP, 184, rue du Faubourg-Saint-Antoine, 75012 Paris, France
| | - S Rivaud-Pechoux
- Inserm U1127, CNRS UMR7225, institut du cerveau et de la moelle épinière, ICM, Paris Sorbonne universités, UPMC, université de Paris 06, UMR S1127, 47, boulevard de l'hôpital, 75651 Paris cedex 13, France
| | - A Bertrand
- Inserm U1127, CNRS UMR7225, institut du cerveau et de la moelle épinière, ICM, Paris Sorbonne universités, UPMC, université de Paris 06, UMR S1127, 47, boulevard de l'hôpital, 75651 Paris cedex 13, France; Service de neuroradiologie diagnostique et fonctionnelle, hôpital Pitié-Salpêtrière, AP-HP, 47, boulevard de l'hôpital, 75651 Paris cedex 13, France
| | - S Dupont
- Unité d'épileptologie, neurologie 1, hôpital Pitié-Salpêtrière, AP-HP, Paris47, boulevard de l'hôpital, 75651 Paris cedex 13, France
| | - V Navarro
- Inserm U1127, CNRS UMR7225, institut du cerveau et de la moelle épinière, ICM, Paris Sorbonne universités, UPMC, université de Paris 06, UMR S1127, 47, boulevard de l'hôpital, 75651 Paris cedex 13, France; Unité d'épileptologie, neurologie 1, hôpital Pitié-Salpêtrière, AP-HP, Paris47, boulevard de l'hôpital, 75651 Paris cedex 13, France
| | - E Roze
- Inserm U1127, CNRS UMR7225, institut du cerveau et de la moelle épinière, ICM, Paris Sorbonne universités, UPMC, université de Paris 06, UMR S1127, 47, boulevard de l'hôpital, 75651 Paris cedex 13, France; Département de neurologie, hôpital Pitié-Salpêtrière, AP-HP, 47, boulevard de l'hôpital, 75651 Paris cedex 13, France
| | - I Gourfinkel-An
- Unité d'épileptologie, neurologie 1, hôpital Pitié-Salpêtrière, AP-HP, Paris47, boulevard de l'hôpital, 75651 Paris cedex 13, France; Centre de référence épilepsie rare, hôpital Pitié-Salpêtrière, AP-HP, Paris, France
| | - E Apartis
- Unité de neurophysiologie, département DéPAS, hôpital Saint-Antoine, AP-HP, 184, rue du Faubourg-Saint-Antoine, 75012 Paris, France; Inserm U1127, CNRS UMR7225, institut du cerveau et de la moelle épinière, ICM, Paris Sorbonne universités, UPMC, université de Paris 06, UMR S1127, 47, boulevard de l'hôpital, 75651 Paris cedex 13, France.
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