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Institut de Neurosciences des Systèmes
Christian-G. Bénar
Institut de Neuroscience des Systèmes, Marseille
Multimodal recordings and signal processing in epilepsy
Séminaire GIPSA LAB, 23 Mars 2017
Institut de Neurosciences des Systèmes
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The « Institut de Neurosciences des Systèmes »
Theoretical Neuroscience Group V Jirsa
Patho-Physiology of Networks C Bernard
Dynamics Cognitive processes D Schon
Dynamical Brain Mapping C Bénar
Clinical Neurophysiology F Bartolomei
Dir. V Jirsa, co-dir. P Chauvel
Institut de Neurosciences des Systèmes
The Marseille MEG Platform
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http://meg.univ-amu.fr
- Within the clinical neurophysiology department
- 4D system (248 magnetometers)
- Open platform (neuroscience)
- Day hospital (2 patients a week)
JM Badier Eng AMU
S Chen Eng Inserm
B Colombet Tech AMU
- Member of France Life Imaging
- Part of 2 « Federation hospitalo universitaire » (Epinext, Dhune)
- Part of Labex BLRI, convergence project ILCB; collaboration CREx; Fédération sciences du cerveau et de la cognition; collaborations INT, LNC, LPC;
MEG sensors
Institut de Neurosciences des Systèmes
Dynamap/MEG team
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Dynamap
JM Badier CG Bénar S Chen B Colombet
B Giusiano, MC-PH, Info
F Bartolomei, PU-PH
A McGonigal, PH
R Carron, MC-PH
S Medina, Eng, PhD
N Roehri, Eng, PhD
F Pizzo, MD, PhD
S Lagarde, MD, PhD
J Régis, PU-PH
I Lambert, MD, PhD
Institut de Neurosciences des Systèmes
Context: presurgical evaluation of epilepsy
• 0.5 to 1% of population has epilepsy
• ~30% are pharmacoresistant
→ can be considered for surgery
• Aim of presurgical evaluation is to delineate the tissues to be resected in order to stop seizures
SEEG
EEG
Phase 1: non-invasive
Phase 2: invasive
Surgery
Institut de Neurosciences des Systèmes
Theme: Multimodal brain mapping
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MEG fMRI
Intracerebral EEG
Axis 1: Links between non-invasive modalities
Axis 2: Compare non invasive/ invasive
EEG
Cognition
Epilepsy
Surgery
Dynamap
Use of simultaneous recordings: EEG-MEG, EEG-fMRI, MEG-SEEG
Institut de Neurosciences des Systèmes
Neurovascular coupling
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Spike sorting
Parametric GLM => higher correlation with putative interneurons Cpnsistent with coupling with high gamma activity ( Logothetis et al 2001)
PC INT
Multimodal recordings in a animal model of epilepsy; Collab. with P Quilichini, A Ivanov, A Ghestem, C Bernard (Physionet), I Vanzetta (INT); F Wendling, S Blanchard LTSI, O David J Warnking GIN, H Benali Multimodel ANR project
Saillet et al J Neurophysiol 2016
MEG epileptic discharge
Anywave software meg.univ-amu.fr 8
Comparison MEG/EEG
SEEG
EEG MEG
Gavaret et al Brain Topogr 2014 MEG reveals bilateral sources confirmed by SEEG 9
SEEG shows complex networks at seizure onset
Bartolomei et al 2001
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Institut de Neurosciences des Systèmes
Example of SEEG network dynamics
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Schwartz et al Epilepsy Res 2011
The epileptogenicity index
EI is higher for -Smaller time of involvement in seizure
-Higher ratio of energy high freq/low freq
Bartolomei et al 2008 12
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Institut de Neurosciences des Systèmes
Overview
1. High frequency oscillations on SEEG
2. Interictal/preictal networks in SEEG and MEG
3. Simultaneous MEG/SEEG recordings
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Institut de Neurosciences des Systèmes
1. SEEG HIGH FREQUENCY ACTIVITIES
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Institut de Neurosciences des Systèmes
Rationale
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Urrestarazu et al Brain 2007 Bénar et al Clin Neurophysiol 2010 See also Jmail et al 2011, 2016
-High frequency activity are a marker of epilepsy - hard to visualize + filtering can produce ringing (« false ripples ») - time frequency representation need to balance energy across frequencies
Projet ANR TechSan ‘FORCE’ (PI P. Kahane), collaboration GIN, LTSI Rennes (F Wendling), CRN Lyon (JP Lachaux), Micromed company
Institut de Neurosciences des Systèmes
The « 1/f » issue: the zHO method
17 Roehri et al IEEE TBME 2016
Institut de Neurosciences des Systèmes
Time-frequency detectors
18 Roehri et al IEEE TBME 2016; see also Jmail et al 2017
-30 patients studied (2930 contacts: 100.5 [89-109] per patient) -5 min NREM slow wave sleep -quantify Seizure Onset Zone with Epileptogenicity index (EI) -quantify interictal period with spike, HFO and HFO co-occuring with spikes rates -partial ROC analysis to determine which markers better predicts the EZ
Application to patients
Roehri et al. in prep 19
Institut de Neurosciences des Systèmes
2. INTERICTAL/PREICTAL NETWORKS
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Institut de Neurosciences des Systèmes
A) PREICTAL NETWORKS IN SEEG
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Institut de Neurosciences des Systèmes
Preictal SEEG
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Courtens et al Brain Connect 2016
h2 Pijn et al 1989, Wendling et al 2001
Beginning of seizure = period of decrease of connectivity, Wendling et al 2003 → what about the preictal phase ?
Institut de Neurosciences des Systèmes
Networks across frequency bands
23 Courtens et al Brain connect 2016
Institut de Neurosciences des Systèmes
B) INTERICTAL NETWORKS IN MEG
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MEG ICA networks
Malinowska et al Hum Brain Mapp 2014 25
Co-occurrence testing
Cf Bourien et al 2005 for co-occurrence in SEEG 26
• significant direction (pairs of spikes)
• spike co-occurrences (significance with non-parametric technique)
Malinowska et al Hum Brain Mapp 2014
Source localisation on components
ICA1
ICA7
ICA6
ICA1
ICA6
ICA7
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L
MEG
SEEG
Malinowska et al, Hum Brain Mapp 2014
MEG ICA networks
-> very good concordance between MEG and SEEG leaders 28
L
MEG
SEEG
L
MEG ICA networks
Malinowska et al, Hum Brain Mapp 2014
-> only part of network can be retrieved 29
Limitations of separate recordings
• Separate MEEG/SEEG recordings may not
record the exact same activity (fluctuations
across brain states)
• Separate recordings do not allow using single
trial fluctuations as source of information
(as in simultaneous EEG-fMRI)
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=> The next step is to record them simultaneously !
Institut de Neurosciences des Systèmes
3. SIMULTANEOUS RECORDINGS
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EEG-MEG-SEG: feasibility
Dubarry et al, NIMG 2014
23 EEG; 72 SEEG; 248 MEG Sampling rate 2035 Hz
32 Limitation in number of SEEG channels
Evoked activity
Dubarry et al, NIMG 2014 33
Source localization (Brainstorm)
Dubarry et al, NIMG 2014
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Single trial analysis
Dubarry et al, NIMG 2014
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Noise issues
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Observation of both high and low frequency noise
Improving the system
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Fixation of cables + MR-compatible 256 channels amplifier
Badier et al under review
Example: Sensitivity
Bénar et al GRETSI 2015, Badier et al under review 38
Visibility of deep mesial structures? (1)
39 PhD work of Francesca Pizzo
H
A3-A4
B5-B6
Higher coherence with contacts in amygdala
Comp. 3
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Visibility of deep mesial structures? (2)
Francesca Pizzo
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Large scale network
Francesca Pizzo
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Local correlation
Francesca Pizzo
Institut de Neurosciences des Systèmes
Application (2): Validation of signal processing
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Dynamap2
MEG-ICA
SEEG
S Medina, N Roehri, AS Dubarry, M Woodman
beamformer surface
depth
Application (3): Clinical Interest
Gavaret et al Epilepsy Res 2016
SEEG-triggered spike average permit to localise a region outside of SEEG implantation 44
Institut de Neurosciences des Systèmes
Translation to clinical research: the AnyWave software
B Colombet JM Badier M Woodman S Medina N Roehri
GARDEL: SEEG semi-automatic labelling
High frequency oscillations
http://meg.univ-amu.fr/AnyWave/download.html
Dynamap1
Epileptogenicity index
Independent component analysis
VIBRATIONS ANR Project
3D Viewer
Colombet et al J Neurosci Meth 2015
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Multiplatform, modular
Acknowledgements
Postdocs, students N Jmail AS Dubarry M Woodman U Malinowska S Courtens J Wirsich N Roehri S Medina F Pizzo
Engineers JM Badier S Chen B Colombet P Marquis Neuroscientists FX Alario C Liegeois Chauvel
Neurologists F Bartolomei P Chauvel M Gavaret A Trébuchon da Fonseca Neurosurgeons J Régis R Carron
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PhD position in MEG signal processing for foreign student!!!
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