The Experts below are selected from a list of 53343 Experts worldwide ranked by ideXlab platform
François Bonnetblanc - One of the best experts on this subject based on the ideXlab platform.
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attenuation and delay of remote potentials evoked by direct electrical stimulation during Brain Surgery
Brain Topography, 2020Co-Authors: Anthony Boyer, Hugues Duffau, Sofiane Ramdani, David Guiraud, François Bonnetblanc, Emmanuel Mandonnet, Marion VincentAbstract:Direct electrical stimulation (DES) is used to perform functional Brain mapping during awake Surgery but its electrophysiological effects remain by far unknown. DES may be coupled with the measurement of evoked potentials (EPs) to study the conductive and integrative properties of activated neural ensembles and probe the spatiotemporal dynamics of short- and long-range networks. We recorded ECoG signals on two patients undergoing awake Brain Surgery and measured EPs on functional sites after cortical stimulations, using combinations of stimulation parameters. EPs were similar in shape but delayed in time and attenuated in amplitude when elicited from a different gyrus or remotely from the recording site. We were able to trigger remote EPs using low stimulation intensities. We propose different activation and electrophysiological propagation mechanisms following DES based on activated neural elements.
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Alterations of EEG rhythms during motor preparation following awake Brain Surgery.
Brain and cognition, 2018Co-Authors: Anthony Boyer, Hugues Duffau, Sofiane Ramdani, Bénédicte Poulin-charronnat, David Guiraud, François BonnetblancAbstract:Slow-growing, infiltrative Brain tumours may modify the electrophysiological balance between the two hemispheres. To determine whether and how asymmetry of EEG rhythms during motor preparation might occur following " awake Brain Surgery " for this type of tumour, we recorded electroencephalograms during a simple visuo-manual reaction time paradigm performed by the patients between 3 and 12 months after Surgery and compared them to a control group of 8 healthy subjects. Frequency analyses revealed imbalances between the injured and healthy hemispheres. More particularly, we observed a power increase in the δ frequency band near the lesion site and a power increase in the α and β frequency bands. Interestingly, these alterations seem to decrease for the two patients whose Surgery were anterior to 9 months, independently of the size of the lesion. Reaction times did not reflect this pattern as they were clearly not inversely related to the anteriority of the Surgery. Electrophysiology suggests here different processes of recovery compared to behavioral data and brings further insights for the understanding of EEG rhythms that should not be systematically confounded or assimilated with cognitive performances. EEG monitoring is rare for these patients, especially after awake Brain Surgery, however it is important.
Hugues Duffau - One of the best experts on this subject based on the ideXlab platform.
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attenuation and delay of remote potentials evoked by direct electrical stimulation during Brain Surgery
Brain Topography, 2020Co-Authors: Anthony Boyer, Hugues Duffau, Sofiane Ramdani, David Guiraud, François Bonnetblanc, Emmanuel Mandonnet, Marion VincentAbstract:Direct electrical stimulation (DES) is used to perform functional Brain mapping during awake Surgery but its electrophysiological effects remain by far unknown. DES may be coupled with the measurement of evoked potentials (EPs) to study the conductive and integrative properties of activated neural ensembles and probe the spatiotemporal dynamics of short- and long-range networks. We recorded ECoG signals on two patients undergoing awake Brain Surgery and measured EPs on functional sites after cortical stimulations, using combinations of stimulation parameters. EPs were similar in shape but delayed in time and attenuated in amplitude when elicited from a different gyrus or remotely from the recording site. We were able to trigger remote EPs using low stimulation intensities. We propose different activation and electrophysiological propagation mechanisms following DES based on activated neural elements.
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Alterations of EEG rhythms during motor preparation following awake Brain Surgery.
Brain and cognition, 2018Co-Authors: Anthony Boyer, Hugues Duffau, Sofiane Ramdani, Bénédicte Poulin-charronnat, David Guiraud, François BonnetblancAbstract:Slow-growing, infiltrative Brain tumours may modify the electrophysiological balance between the two hemispheres. To determine whether and how asymmetry of EEG rhythms during motor preparation might occur following " awake Brain Surgery " for this type of tumour, we recorded electroencephalograms during a simple visuo-manual reaction time paradigm performed by the patients between 3 and 12 months after Surgery and compared them to a control group of 8 healthy subjects. Frequency analyses revealed imbalances between the injured and healthy hemispheres. More particularly, we observed a power increase in the δ frequency band near the lesion site and a power increase in the α and β frequency bands. Interestingly, these alterations seem to decrease for the two patients whose Surgery were anterior to 9 months, independently of the size of the lesion. Reaction times did not reflect this pattern as they were clearly not inversely related to the anteriority of the Surgery. Electrophysiology suggests here different processes of recovery compared to behavioral data and brings further insights for the understanding of EEG rhythms that should not be systematically confounded or assimilated with cognitive performances. EEG monitoring is rare for these patients, especially after awake Brain Surgery, however it is important.
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Mapping of visuospatial functions during Brain Surgery: a new tool to prevent unilateral spatial neglect.
Neurosurgery, 2007Co-Authors: Paolo Bartolomeo, Michel Thiebaut De Schotten, Hugues DuffauAbstract:Mapping of visuospatial functions during Brain Surgery: a new tool to prevent unilateral spatial neglec
Agnès Trébuchon - One of the best experts on this subject based on the ideXlab platform.
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In Vivo Tumour Mapping Using Electrocorticography Alterations During Awake Brain Surgery: A Pilot Study
Brain Topography: a Journal of Cerebral Function and Dynamics, 2016Co-Authors: Salah Boussen, Lionel Velly, Christian Bénar, Philippe Metellus, Nicolas Bruder, Agnès TrébuchonAbstract:During awake Brain Surgery for tumour resection, in situ EEG recording (ECoG) is used to identify eloquent areas surrounding the tumour. We used the ECoG setup to record the electrical activity of cortical and subcortical tumours and then performed frequency and connectivity analyses in order to identify ECoG impairments and map tumours. We selected 16 patients with cortical (8) and subcortical (8) tumours undergoing awake Brain Surgery. For each patient, we computed the spectral content of tumoural and healthy areas in each frequency band. We computed connectivity of each electrode using connectivity markers (linear and non-linear correlations, phase-locking and coherence). We performed comparisons between healthy and tumour electrodes. The ECoG alterations were used to implement automated classification of the electrodes using clustering or neural network algorithms. ECoG alterations were used to image cortical tumours.Cortical tumours were found to profoundly alter all frequency contents (normalized and absolute power), with an increase in the delta activity and a decreases for the other bands (P < 0.05). Cortical tumour electrodes showed high level of connectivity compared to surrounding electrodes (all markers, P < 0.05). For subcortical tumours, a relative decrease in the gamma 1 band and in the alpha band in absolute amplitude (P < 0.05) were the only abnormalities. The neural network algorithm classification had a good performance: 93.6 % of the electrodes were classified adequately on a test subject. We found significant spectral and connectivity ECoG changes for cortical tumours, which allowed tumour recognition. Artificial neural algorithm pattern recognition seems promising for electrode classification in awake tumour Surgery.
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In Vivo Tumour Mapping Using Electrocorticography Alterations During Awake Brain Surgery: A Pilot Study
Brain Topography, 2016Co-Authors: Salah Boussen, Lionel Velly, Christian Bénar, Philippe Metellus, Nicolas Bruder, Agnès TrébuchonAbstract:During awake Brain Surgery for tumour resection, in situ EEG recording (ECoG) is used to identify eloquent areas surrounding the tumour. We used the ECoG setup to record the electrical activity of cortical and subcortical tumours and then performed frequency and connectivity analyses in order to identify ECoG impairments and map tumours. We selected 16 patients with cortical (8) and subcortical (8) tumours undergoing awake Brain Surgery. For each patient, we computed the spectral content of tumoural and healthy areas in each frequency band. We computed connectivity of each electrode using connectivity markers (linear and non-linear correlations, phase-locking and coherence). We performed comparisons between healthy and tumour electrodes. The ECoG alterations were used to implement automated classification of the electrodes using clustering or neural network algorithms. ECoG alterations were used to image cortical tumours.Cortical tumours were found to profoundly alter all frequency contents (normalized and absolute power), with an increase in the δ activity and a decreases for the other bands (P
Robert F. Heimburger - One of the best experts on this subject based on the ideXlab platform.
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An encounter with stereotactic Brain Surgery.
Neurosurgery, 2005Co-Authors: Robert F. HeimburgerAbstract:A historical account of the "medieval" period of stereotactic Brain Surgery characterizes it as a time of instrument development, choosing of treatment targets, and close rapport between patients and neurological surgeons. Pioneers had frequent contact with the next tier of investigators. Brain function and instrumentation became better understood, leading to the more recent exponential advancements in the field.
Anthony Boyer - One of the best experts on this subject based on the ideXlab platform.
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attenuation and delay of remote potentials evoked by direct electrical stimulation during Brain Surgery
Brain Topography, 2020Co-Authors: Anthony Boyer, Hugues Duffau, Sofiane Ramdani, David Guiraud, François Bonnetblanc, Emmanuel Mandonnet, Marion VincentAbstract:Direct electrical stimulation (DES) is used to perform functional Brain mapping during awake Surgery but its electrophysiological effects remain by far unknown. DES may be coupled with the measurement of evoked potentials (EPs) to study the conductive and integrative properties of activated neural ensembles and probe the spatiotemporal dynamics of short- and long-range networks. We recorded ECoG signals on two patients undergoing awake Brain Surgery and measured EPs on functional sites after cortical stimulations, using combinations of stimulation parameters. EPs were similar in shape but delayed in time and attenuated in amplitude when elicited from a different gyrus or remotely from the recording site. We were able to trigger remote EPs using low stimulation intensities. We propose different activation and electrophysiological propagation mechanisms following DES based on activated neural elements.
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Alterations of EEG rhythms during motor preparation following awake Brain Surgery.
Brain and cognition, 2018Co-Authors: Anthony Boyer, Hugues Duffau, Sofiane Ramdani, Bénédicte Poulin-charronnat, David Guiraud, François BonnetblancAbstract:Slow-growing, infiltrative Brain tumours may modify the electrophysiological balance between the two hemispheres. To determine whether and how asymmetry of EEG rhythms during motor preparation might occur following " awake Brain Surgery " for this type of tumour, we recorded electroencephalograms during a simple visuo-manual reaction time paradigm performed by the patients between 3 and 12 months after Surgery and compared them to a control group of 8 healthy subjects. Frequency analyses revealed imbalances between the injured and healthy hemispheres. More particularly, we observed a power increase in the δ frequency band near the lesion site and a power increase in the α and β frequency bands. Interestingly, these alterations seem to decrease for the two patients whose Surgery were anterior to 9 months, independently of the size of the lesion. Reaction times did not reflect this pattern as they were clearly not inversely related to the anteriority of the Surgery. Electrophysiology suggests here different processes of recovery compared to behavioral data and brings further insights for the understanding of EEG rhythms that should not be systematically confounded or assimilated with cognitive performances. EEG monitoring is rare for these patients, especially after awake Brain Surgery, however it is important.