The Experts below are selected from a list of 7974 Experts worldwide ranked by ideXlab platform
Fabrice Bartolomei - One of the best experts on this subject based on the ideXlab platform.
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How does vagal nerve stimulation (VNS) change EEG brain functional connectivity?
Epilepsy Research, 2016Co-Authors: Fabrice Bartolomei, Francesca Bonini, Romain Carron, Elsa Vidal, Agnès Trébuchon, Stanislas Lagarde, Isabelle Lambert, Aileen Mcgonigal, Didier Scavarda, Christian BénarAbstract:An effect of vagal nerve stimulation (VNS) on Cortical Synchronization has been postulated but remains to be verified. In this study we investigated the impact of VNS on functional connectivity (Fc) using direct intracerebral recordings (stereotactic EEG, SEEG). Five patients with epilepsy who underwent SEEG recordings during ongoing VNS therapy were investigated. Interdependencies between twenty-six selected bipolar SEEG channels were estimated by nonlinear regression analysis during ON and OF periods of stimulation. In comparison with OFF periods, the ON periods disclosed higher values for four patients (P1, P3, P4, P5) and lower values for one patient (P2). From thresholded graphs, we observed increased connections between several brain regions in P1 and P5 and decreased connections in P2. Finally, the only decreased Fc occurring during VNS corresponded to the responder patient, suggesting that therapeutic impact might be related to this mechanism. (C) 2016 Elsevier B.V. All rights reserved.
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How does vagal nerve stimulation (VNS) change EEG brain functional connectivity
Epilepsy research, 2016Co-Authors: Fabrice Bartolomei, Francesca Bonini, Romain Carron, Elsa Vidal, Agnès Trébuchon, Stanislas Lagarde, Isabelle Lambert, Aileen Mcgonigal, Didier Scavarda, Christian BénarAbstract:An effect of vagal nerve stimulation (VNS) on Cortical Synchronization has been postulated but remains to be verified. In this study we investigated the impact of VNS on functional connectivity (Fc) using direct intracerebral recordings (stereotactic EEG, SEEG). Five patients with epilepsy who underwent SEEG recordings during ongoing VNS therapy were investigated. Interdependencies between twenty-six selected bipolar SEEG channels were estimated by nonlinear regression analysis during ON and OF periods of stimulation. In comparison with OFF periods, the ON periods disclosed higher values for four patients (P1, P3, P4, P5) and lower values for one patient (P2). From thresholded graphs, we observed increased connections between several brain regions in P1 and P5 and decreased connections in P2. Finally, the only decreased Fc occurring during VNS corresponded to the responder patient, suggesting that therapeutic impact might be related to this mechanism.
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Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?
Frontiers in neurology, 2015Co-Authors: Elisa Evangelista, Christian Bénar, Francesca Bonini, Romain Carron, Bruno Colombet, Jean Régis, Fabrice BartolomeiAbstract:The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-Cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from ten patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings (stereoelectroencephalography, SEEG). We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and Cortical regions. Then we derived Synchronization indices, namely global, thalamic, mesio-temporal and thalamo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic “outputs and inputs” connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic Synchronization index was significantly more elevated at the end of seizure than at the onset. The global Synchronization index at the end of seizure negatively correlated with seizure duration (p= 0.045) and in the same way the thalamic Synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-Cortical spike and wave pattern (SWP) at the end. They were associated to higher values of all Synchronization indices and outputs from thalamus ( p = 0.0079). SWP seizures displayed a higher and sustained increase of Cortical and thalamo-Cortical Synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-Cortical oscillations might contribute to seizure termination via modulation of Cortical Synchronization. In the subgroup of SWP seizures thalamus may exert a control on temporal lobe structures by inducing a stable hyperSynchronization that ultimately leads to seizure termination.
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Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?
Frontiers in Neurology, 2015Co-Authors: Elisa Evangelista, Christian Bénar, Francesca Bonini, Romain Carron, Bruno Colombet, Jean Régis, Fabrice BartolomeiAbstract:The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-Cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from 10 patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings [stereoelectroencephalography (SEEG)]. We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and Cortical regions. Then, we derived Synchronization indices, namely global, thalamic, mesio-temporal, and thala-mo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic " outputs and inputs " connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic Synchronization index was significantly more elevated at the end of seizure than at the onset. The global Synchronization index at the end of seizure negatively correlated with seizure duration (p = 0.045) and in the same way the thalamic Synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-Cortical spike-and-wave pattern at the end. They were associated to higher values of all Synchronization indices and outputs from thalamus (p = 0.0079). SWP seizures displayed a higher and sustained increase of Cortical and thalamo-Cortical Synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-Cortical oscillations might contribute to seizure termination via modulation of Cortical Synchronization. In the subgroup of SWP seizures, thalamus may exert a control on temporal lobe structures by inducing a stable hyperSynchronization that ultimately leads to seizure termination.
Christian Bénar - One of the best experts on this subject based on the ideXlab platform.
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How does vagal nerve stimulation (VNS) change EEG brain functional connectivity?
Epilepsy Research, 2016Co-Authors: Fabrice Bartolomei, Francesca Bonini, Romain Carron, Elsa Vidal, Agnès Trébuchon, Stanislas Lagarde, Isabelle Lambert, Aileen Mcgonigal, Didier Scavarda, Christian BénarAbstract:An effect of vagal nerve stimulation (VNS) on Cortical Synchronization has been postulated but remains to be verified. In this study we investigated the impact of VNS on functional connectivity (Fc) using direct intracerebral recordings (stereotactic EEG, SEEG). Five patients with epilepsy who underwent SEEG recordings during ongoing VNS therapy were investigated. Interdependencies between twenty-six selected bipolar SEEG channels were estimated by nonlinear regression analysis during ON and OF periods of stimulation. In comparison with OFF periods, the ON periods disclosed higher values for four patients (P1, P3, P4, P5) and lower values for one patient (P2). From thresholded graphs, we observed increased connections between several brain regions in P1 and P5 and decreased connections in P2. Finally, the only decreased Fc occurring during VNS corresponded to the responder patient, suggesting that therapeutic impact might be related to this mechanism. (C) 2016 Elsevier B.V. All rights reserved.
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How does vagal nerve stimulation (VNS) change EEG brain functional connectivity
Epilepsy research, 2016Co-Authors: Fabrice Bartolomei, Francesca Bonini, Romain Carron, Elsa Vidal, Agnès Trébuchon, Stanislas Lagarde, Isabelle Lambert, Aileen Mcgonigal, Didier Scavarda, Christian BénarAbstract:An effect of vagal nerve stimulation (VNS) on Cortical Synchronization has been postulated but remains to be verified. In this study we investigated the impact of VNS on functional connectivity (Fc) using direct intracerebral recordings (stereotactic EEG, SEEG). Five patients with epilepsy who underwent SEEG recordings during ongoing VNS therapy were investigated. Interdependencies between twenty-six selected bipolar SEEG channels were estimated by nonlinear regression analysis during ON and OF periods of stimulation. In comparison with OFF periods, the ON periods disclosed higher values for four patients (P1, P3, P4, P5) and lower values for one patient (P2). From thresholded graphs, we observed increased connections between several brain regions in P1 and P5 and decreased connections in P2. Finally, the only decreased Fc occurring during VNS corresponded to the responder patient, suggesting that therapeutic impact might be related to this mechanism.
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Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?
Frontiers in neurology, 2015Co-Authors: Elisa Evangelista, Christian Bénar, Francesca Bonini, Romain Carron, Bruno Colombet, Jean Régis, Fabrice BartolomeiAbstract:The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-Cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from ten patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings (stereoelectroencephalography, SEEG). We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and Cortical regions. Then we derived Synchronization indices, namely global, thalamic, mesio-temporal and thalamo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic “outputs and inputs” connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic Synchronization index was significantly more elevated at the end of seizure than at the onset. The global Synchronization index at the end of seizure negatively correlated with seizure duration (p= 0.045) and in the same way the thalamic Synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-Cortical spike and wave pattern (SWP) at the end. They were associated to higher values of all Synchronization indices and outputs from thalamus ( p = 0.0079). SWP seizures displayed a higher and sustained increase of Cortical and thalamo-Cortical Synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-Cortical oscillations might contribute to seizure termination via modulation of Cortical Synchronization. In the subgroup of SWP seizures thalamus may exert a control on temporal lobe structures by inducing a stable hyperSynchronization that ultimately leads to seizure termination.
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Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?
Frontiers in Neurology, 2015Co-Authors: Elisa Evangelista, Christian Bénar, Francesca Bonini, Romain Carron, Bruno Colombet, Jean Régis, Fabrice BartolomeiAbstract:The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-Cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from 10 patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings [stereoelectroencephalography (SEEG)]. We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and Cortical regions. Then, we derived Synchronization indices, namely global, thalamic, mesio-temporal, and thala-mo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic " outputs and inputs " connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic Synchronization index was significantly more elevated at the end of seizure than at the onset. The global Synchronization index at the end of seizure negatively correlated with seizure duration (p = 0.045) and in the same way the thalamic Synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-Cortical spike-and-wave pattern at the end. They were associated to higher values of all Synchronization indices and outputs from thalamus (p = 0.0079). SWP seizures displayed a higher and sustained increase of Cortical and thalamo-Cortical Synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-Cortical oscillations might contribute to seizure termination via modulation of Cortical Synchronization. In the subgroup of SWP seizures, thalamus may exert a control on temporal lobe structures by inducing a stable hyperSynchronization that ultimately leads to seizure termination.
Giulio Tononi - One of the best experts on this subject based on the ideXlab platform.
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Sleep homeostasis and Cortical Synchronization: I. Modeling the effects of synaptic strength on sleep slow waves.
Sleep, 2007Co-Authors: Steven K. Esser, Sean Hill, Giulio TononiAbstract:SLOW WAVES ARE A PROMINENT FEATURE OF NON-RAPID EYE MOVEMENT (NREM) SLEEP THAT CAN BE OBSERVED IN THE ELECTROENCEPHALOGRAM (EEG) and local field potentials (LFP). Slow-wave activity (SWA, EEG power 0.5–4.0 Hz) provides a reliable indicator of sleep need, as it increases as a function of prior waking and declines during sleep.1–3 Although the homeostatic regulation of SWA is suggestive of a restorative function of sleep, the underlying mechanisms remain unknown. Different mechanisms can be conceived that might lead to a progressive decline in SWA during sleep, such as an increase in the level of arousal-promoting neuromodulators or a reduction of accumulated metabolites (e.g., adenosine). A recent proposal suggests that the level of SWA may reflect the strength of corticoCortical synapses and that a progressive reduction in synaptic strength during sleep would be associated with a corresponding decrease in SWA.4, 5 Mechanistically, stronger Cortical connections would produce stronger network Synchronization and thus a higher level of SWA, whereas weaker connections would reduce network Synchronization and thereby SWA. Connections would become. on average, stronger at the end of a waking day due to synaptic potentiation associated with learning and would weaken during sleep due to sleep-dependent synaptic depression, as suggested by molecular and other evidence.4, 5 Supporting the hypothesis, procedures associated with synaptic potentiation and depression in local Cortical areas lead to corresponding changes in sleep SWA. For example, sleep SWA increases over right parietal cortex after a visuomotor learning task6 and decreases over the right sensorimotor cortex after immobilization of the left arm.7 In this paper, we employed a large-scale computer model of the cat thalamoCortical system to investigate in detail the relationship between synaptic strength and SWA. The model incorporates key aspects of the neuroanatomic organization of visual thalamoCortical circuits, including more than 65,000 integrate-and-fire neurons organized into multiple Cortical, thalamic, and reticular areas, and produces physiologically realistic sleep activity patterns.8 Specifically, due to the interaction between several intrinsic and synaptic currents, simulated neurons undergo slow oscillations at around 1 Hz between depolarized periods of activity (up states) and hyperpolarized periods of silence (down states), as observed in intracellular recordings in vivo.9, 10 These single-cell oscillations are synchronized by corticoCortical connections and produce realistic slow waves in the calculated LFP. On the basis of this model, we examined the dynamics of single-cell oscillations, Cortical Synchronization, and LFP slow waves under conditions with a high or low strength of corticoCortical connections. We show here that a reduction in Cortical synaptic strength leads to a decrease in sleep SWA, a decreased incidence of large-amplitude slow waves, a decrease in their slope, and an increase in the number of multipeak waves. In 2 companion papers, we tested the predictions of the model by examining how slow waves change between early-sleep and late-sleep conditions using LFP recordings in rats11 and high-density EEG recordings in humans.12
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Sleep homeostasis and Cortical Synchronization: III. A high-density EEG study of sleep slow waves in humans.
Sleep, 2007Co-Authors: Brady A. Riedner, Steven K. Esser, Vladyslav V. Vyazovskiy, Reto Huber, Marcello Massimini, Michael Murphy, Giulio TononiAbstract:SLOW WAVES ARE THE MOST OBVIOUS AND RECOGNIZABLE FEATURE OF THE HUMAN SLEEP EEG. IN ADDITION TO BEING INDICATIVE OF SLEEP DEPTH,5 SLOW waves are intimately related to sleep regulation: it is well known that SWA (EEG power between 0.5 and 4.0 Hz), which reflects the abundance of low-frequency waves in the EEG, increases as a function of prior waking and declines throughout the course of sleep.6–8 Although the regulation of SWA is suggestive of a restorative function of sleep, the mechanisms responsible for SWA homeostasis remain unclear. It was recently suggested that the level of SWA during sleep may be a function of the strength of Cortical synapses due to the influence of synaptic efficacy on network Synchronization.1, 2 According to the hypothesis, at the beginning of sleep, synaptic strength would be high due to learning processes occurring during wakefulness, whereas, by the end of sleep, synaptic strength would have decreased through a sleep-dependent process of synaptic downscaling. The hypothesized relationship between synaptic strength and the level of SWA was investigated in a companion paper using a large-scale model of sleep in the thalamoCortical system.3 The simulation showed that decreasing synaptic strength among Cortical neurons led to a decrease in sleep SWA.3 Intriguingly, synaptic strength reduction also resulted in characteristic changes to several slow-wave parameters, including a decrease in the number of high-amplitude slow waves, a decrease in the slope of slow waves, and more frequent waves with multiple peaks. In a second companion paper, we tested the model's predictions by employing local field potential (LFP) recordings in the rat to compare periods of early and late sleep.4 We found that the decline in SWA in the LFP was associated with the changes in slow-wave parameters predicted by the model. Furthermore, recovery after sleep deprivation resulted in an increased number of high-amplitude slow waves, steeper slopes, and fewer multipeak waves, suggesting that these observed changes in slow-wave parameters are a result of homeostatic sleep regulation and not circadian time. In the present paper, we tested the model's predictions in humans. We used all-night high-density EEG (hd-EEG) recordings to compare non-rapid eye movement (NREM) sleep slow waves at the beginning of the night, when the pressure to sleep is highest, to NREM sleep slow waves toward morning, when sleep pressure has largely dissipated. We found that, as predicted by computer simulations, and in line with rat LFP recordings, the homeostatic decline of SWA during sleep is coupled with a decreased incidence of high-amplitude slow waves, a decreased slope of slow waves, and an increased number of multipeak waves. Moreover, we found that individual peaks of the multipeak waves characteristic of late sleep have distinct Cortical origins.
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Sleep Homeostasis and Cortical Synchronization: II. A Local Field Potential Study of Sleep Slow Waves in the Rat
Sleep, 2007Co-Authors: Vladyslav V. Vyazovskiy, Brady A. Riedner, Chiara Cirelli, Giulio TononiAbstract:Study Objective: Sleep slow-wave activity (SWA, EEG power between 0.5 and 4.0 Hz) decreases homeostatically in the course of non-rapid eye movement sleep (NREM) sleep. According to a recent hypothesis, the homeostatic decrease of sleep SWA is due to a progressive decrease in the strength of corticoCortical connections. This hypothesis was evaluated in a large-scale thalamoCortical model, which showed that a decrease in synaptic strength, implemented through a reduction of postsynaptic currents, resulted in lower sleep SWA in simulated local field potentials (LFP). The decrease in SWA was associated with a decreased proportion of high-amplitude slow waves, a decreased slope of the slow waves, and an increase in the number of multipeak waves. Here we tested the model predictions by obtaining LFP recordings from the rat cerebral cortex and comparing conditions of high homeostatic sleep pressure (early sleep) and low homeostatic sleep pressure (late sleep). Design: IntraCortical LFP recordings during baseline sleep and after 6 hours of sleep deprivation. Setting: Basic sleep research laboratory. Patients or Participants: WKY adult male rats. Interventions: N/A. Measurements and Results: Early sleep (sleep at the beginning of the major sleep phase, sleep immediately after sleep deprivation) was associated with (1) high SWA, (2) many large slow waves, (3) steep slope of slow waves, and (4) rare occurrence of multipeak waves. By contrast, late sleep (sleep at the end of the major sleep phase, sleep several hours after the end of sleep deprivation) was associated with (1) low SWA, (2) few high-amplitude slow waves, (3) reduced slope of slow waves, and (4) more frequent multipeak waves. Conclusion: In rats, changes in sleep SWA are associated with changes in the amplitude and slope of slow waves, and in the number of multipeak waves. Such changes in slow-wave parameters are compatible with the hypothesis that average synaptic strength decreases in the course of sleep.
Francesca Bonini - One of the best experts on this subject based on the ideXlab platform.
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How does vagal nerve stimulation (VNS) change EEG brain functional connectivity?
Epilepsy Research, 2016Co-Authors: Fabrice Bartolomei, Francesca Bonini, Romain Carron, Elsa Vidal, Agnès Trébuchon, Stanislas Lagarde, Isabelle Lambert, Aileen Mcgonigal, Didier Scavarda, Christian BénarAbstract:An effect of vagal nerve stimulation (VNS) on Cortical Synchronization has been postulated but remains to be verified. In this study we investigated the impact of VNS on functional connectivity (Fc) using direct intracerebral recordings (stereotactic EEG, SEEG). Five patients with epilepsy who underwent SEEG recordings during ongoing VNS therapy were investigated. Interdependencies between twenty-six selected bipolar SEEG channels were estimated by nonlinear regression analysis during ON and OF periods of stimulation. In comparison with OFF periods, the ON periods disclosed higher values for four patients (P1, P3, P4, P5) and lower values for one patient (P2). From thresholded graphs, we observed increased connections between several brain regions in P1 and P5 and decreased connections in P2. Finally, the only decreased Fc occurring during VNS corresponded to the responder patient, suggesting that therapeutic impact might be related to this mechanism. (C) 2016 Elsevier B.V. All rights reserved.
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How does vagal nerve stimulation (VNS) change EEG brain functional connectivity
Epilepsy research, 2016Co-Authors: Fabrice Bartolomei, Francesca Bonini, Romain Carron, Elsa Vidal, Agnès Trébuchon, Stanislas Lagarde, Isabelle Lambert, Aileen Mcgonigal, Didier Scavarda, Christian BénarAbstract:An effect of vagal nerve stimulation (VNS) on Cortical Synchronization has been postulated but remains to be verified. In this study we investigated the impact of VNS on functional connectivity (Fc) using direct intracerebral recordings (stereotactic EEG, SEEG). Five patients with epilepsy who underwent SEEG recordings during ongoing VNS therapy were investigated. Interdependencies between twenty-six selected bipolar SEEG channels were estimated by nonlinear regression analysis during ON and OF periods of stimulation. In comparison with OFF periods, the ON periods disclosed higher values for four patients (P1, P3, P4, P5) and lower values for one patient (P2). From thresholded graphs, we observed increased connections between several brain regions in P1 and P5 and decreased connections in P2. Finally, the only decreased Fc occurring during VNS corresponded to the responder patient, suggesting that therapeutic impact might be related to this mechanism.
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Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?
Frontiers in neurology, 2015Co-Authors: Elisa Evangelista, Christian Bénar, Francesca Bonini, Romain Carron, Bruno Colombet, Jean Régis, Fabrice BartolomeiAbstract:The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-Cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from ten patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings (stereoelectroencephalography, SEEG). We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and Cortical regions. Then we derived Synchronization indices, namely global, thalamic, mesio-temporal and thalamo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic “outputs and inputs” connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic Synchronization index was significantly more elevated at the end of seizure than at the onset. The global Synchronization index at the end of seizure negatively correlated with seizure duration (p= 0.045) and in the same way the thalamic Synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-Cortical spike and wave pattern (SWP) at the end. They were associated to higher values of all Synchronization indices and outputs from thalamus ( p = 0.0079). SWP seizures displayed a higher and sustained increase of Cortical and thalamo-Cortical Synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-Cortical oscillations might contribute to seizure termination via modulation of Cortical Synchronization. In the subgroup of SWP seizures thalamus may exert a control on temporal lobe structures by inducing a stable hyperSynchronization that ultimately leads to seizure termination.
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Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?
Frontiers in Neurology, 2015Co-Authors: Elisa Evangelista, Christian Bénar, Francesca Bonini, Romain Carron, Bruno Colombet, Jean Régis, Fabrice BartolomeiAbstract:The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-Cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from 10 patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings [stereoelectroencephalography (SEEG)]. We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and Cortical regions. Then, we derived Synchronization indices, namely global, thalamic, mesio-temporal, and thala-mo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic " outputs and inputs " connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic Synchronization index was significantly more elevated at the end of seizure than at the onset. The global Synchronization index at the end of seizure negatively correlated with seizure duration (p = 0.045) and in the same way the thalamic Synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-Cortical spike-and-wave pattern at the end. They were associated to higher values of all Synchronization indices and outputs from thalamus (p = 0.0079). SWP seizures displayed a higher and sustained increase of Cortical and thalamo-Cortical Synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-Cortical oscillations might contribute to seizure termination via modulation of Cortical Synchronization. In the subgroup of SWP seizures, thalamus may exert a control on temporal lobe structures by inducing a stable hyperSynchronization that ultimately leads to seizure termination.
Romain Carron - One of the best experts on this subject based on the ideXlab platform.
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How does vagal nerve stimulation (VNS) change EEG brain functional connectivity?
Epilepsy Research, 2016Co-Authors: Fabrice Bartolomei, Francesca Bonini, Romain Carron, Elsa Vidal, Agnès Trébuchon, Stanislas Lagarde, Isabelle Lambert, Aileen Mcgonigal, Didier Scavarda, Christian BénarAbstract:An effect of vagal nerve stimulation (VNS) on Cortical Synchronization has been postulated but remains to be verified. In this study we investigated the impact of VNS on functional connectivity (Fc) using direct intracerebral recordings (stereotactic EEG, SEEG). Five patients with epilepsy who underwent SEEG recordings during ongoing VNS therapy were investigated. Interdependencies between twenty-six selected bipolar SEEG channels were estimated by nonlinear regression analysis during ON and OF periods of stimulation. In comparison with OFF periods, the ON periods disclosed higher values for four patients (P1, P3, P4, P5) and lower values for one patient (P2). From thresholded graphs, we observed increased connections between several brain regions in P1 and P5 and decreased connections in P2. Finally, the only decreased Fc occurring during VNS corresponded to the responder patient, suggesting that therapeutic impact might be related to this mechanism. (C) 2016 Elsevier B.V. All rights reserved.
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How does vagal nerve stimulation (VNS) change EEG brain functional connectivity
Epilepsy research, 2016Co-Authors: Fabrice Bartolomei, Francesca Bonini, Romain Carron, Elsa Vidal, Agnès Trébuchon, Stanislas Lagarde, Isabelle Lambert, Aileen Mcgonigal, Didier Scavarda, Christian BénarAbstract:An effect of vagal nerve stimulation (VNS) on Cortical Synchronization has been postulated but remains to be verified. In this study we investigated the impact of VNS on functional connectivity (Fc) using direct intracerebral recordings (stereotactic EEG, SEEG). Five patients with epilepsy who underwent SEEG recordings during ongoing VNS therapy were investigated. Interdependencies between twenty-six selected bipolar SEEG channels were estimated by nonlinear regression analysis during ON and OF periods of stimulation. In comparison with OFF periods, the ON periods disclosed higher values for four patients (P1, P3, P4, P5) and lower values for one patient (P2). From thresholded graphs, we observed increased connections between several brain regions in P1 and P5 and decreased connections in P2. Finally, the only decreased Fc occurring during VNS corresponded to the responder patient, suggesting that therapeutic impact might be related to this mechanism.
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Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?
Frontiers in neurology, 2015Co-Authors: Elisa Evangelista, Christian Bénar, Francesca Bonini, Romain Carron, Bruno Colombet, Jean Régis, Fabrice BartolomeiAbstract:The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-Cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from ten patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings (stereoelectroencephalography, SEEG). We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and Cortical regions. Then we derived Synchronization indices, namely global, thalamic, mesio-temporal and thalamo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic “outputs and inputs” connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic Synchronization index was significantly more elevated at the end of seizure than at the onset. The global Synchronization index at the end of seizure negatively correlated with seizure duration (p= 0.045) and in the same way the thalamic Synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-Cortical spike and wave pattern (SWP) at the end. They were associated to higher values of all Synchronization indices and outputs from thalamus ( p = 0.0079). SWP seizures displayed a higher and sustained increase of Cortical and thalamo-Cortical Synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-Cortical oscillations might contribute to seizure termination via modulation of Cortical Synchronization. In the subgroup of SWP seizures thalamus may exert a control on temporal lobe structures by inducing a stable hyperSynchronization that ultimately leads to seizure termination.
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Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?
Frontiers in Neurology, 2015Co-Authors: Elisa Evangelista, Christian Bénar, Francesca Bonini, Romain Carron, Bruno Colombet, Jean Régis, Fabrice BartolomeiAbstract:The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-Cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from 10 patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings [stereoelectroencephalography (SEEG)]. We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and Cortical regions. Then, we derived Synchronization indices, namely global, thalamic, mesio-temporal, and thala-mo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic " outputs and inputs " connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic Synchronization index was significantly more elevated at the end of seizure than at the onset. The global Synchronization index at the end of seizure negatively correlated with seizure duration (p = 0.045) and in the same way the thalamic Synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-Cortical spike-and-wave pattern at the end. They were associated to higher values of all Synchronization indices and outputs from thalamus (p = 0.0079). SWP seizures displayed a higher and sustained increase of Cortical and thalamo-Cortical Synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-Cortical oscillations might contribute to seizure termination via modulation of Cortical Synchronization. In the subgroup of SWP seizures, thalamus may exert a control on temporal lobe structures by inducing a stable hyperSynchronization that ultimately leads to seizure termination.
