Detection and localization of deep sources in magnetoencephalography: A review

Bénar, Christian‐George; Velmurugan, J; López‐Madrona, Víctor J.; Pizzo, Francesca; Badier, Jean‐Michel

doi:10.1016/j.cobme.2021.100285

Cited by 15 publications

(17 citation statements)

References 74 publications

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“…ICA has been long used in surface recordings, removing noisy components, such as cardiac activity or eye blinking [ 32 ], and identifying task-related neural sources [ 33 , 34 ] or epileptic generators [ 35 , 36 ]. Moreover, it has been proposed as a tool to disentangle deep brain activities hidden at the surface by superficial signals with higher amplitudes [ 37 ]. Although its use in intracranial recordings is reduced in comparison, its effectiveness has been well studied [ 31 , 38 ], and it has been used to dissociate local and remote cortical field potentials [ 39 , 40 ] and different current generators in the hippocampus [ 7 , 16 , 41 , 42 ].…”

Section: Methodsmentioning

confidence: 99%

Functional Interactions between Entorhinal Cortical Pathways Modulate Theta Activity in the Hippocampus

López‐Madrona

Canals

2021

Biology

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Theta oscillations organize neuronal firing in the hippocampus during context exploration and memory formation. Recently, we have shown that multiple theta rhythms coexist in the hippocampus, reflecting the activity in their afferent regions in CA3 (Schaffer collaterals) and the entorhinal cortex layers II (EC-II, perforant pathway) and III (EC-III, temporoammonic pathway). Frequency and phase coupling between theta rhythms were modulated by the behavioral state, with synchronized theta rhythmicity preferentially occurring in tasks involving memory updating. However, information transmission between theta generators was not investigated. Here, we used source separation techniques to disentangle the current generators recorded in the hippocampus of rats exploring a known environment with or without a novel stimulus. We applied analytical tools based on Granger causality and transfer entropy to investigate linear and non-linear directed interactions, respectively, between the theta activities. Exploration in the novelty condition was associated with increased theta power in the generators with EC origin. We found a significant directed interaction from the Schaffer input over the EC-III input in CA1, and a bidirectional interaction between the inputs in the hippocampus originating in the EC, likely reflecting the connection between layers II and III. During novelty exploration, the influence of the EC-II over the EC-III generator increased, while the Schaffer influence decreased. These results associate the increase in hippocampal theta activity and synchrony during novelty exploration with an increase in the directed functional connectivity from EC-II to EC-III.

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Section: Methodsmentioning

confidence: 99%

Functional Interactions between Entorhinal Cortical Pathways Modulate Theta Activity in the Hippocampus

López‐Madrona

Canals

2021

Biology

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“…This is largely due to the fact that MEG is less sensitive to deep cortical sources and subcortical sources ( Agirre-Arrizubieta et al, 2009 , Attal et al, 2009 , Ahlfors et al, 2010 , Wennberg et al, 2011 , Attal and Schwartz, 2013 ). Deep source localization has long been considered a difficult problem ( Hillebrand and Barnes, 2002 , Attal et al, 2009 ), especially given the need for the development of radically new algorithms capable of achieving such a goal ( Krishnaswamy et al, 2017 , Bénar et al, 2021 ). Recent attempts have been made to address the issue, but such studies usually require the aid of simultaneous intracranial recordings ( Juárez-Martinez et al, 2018 , Pizzo et al, 2019 , Pellegrino et al, 2020 ) or prior knowledge of the activation patterns ( Krishnaswamy et al, 2017 ) while large-scale validation is still not available.…”

Section: Discussionmentioning

confidence: 99%

Imaging the extent and location of spatiotemporally distributed epileptiform sources from MEG measurements

Jiang

Sohrabpour

et al. 2022

NeuroImage: Clinical

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Highlights Evaluation of epilepsy source extent estimation from MEG measurements. FAST-IRES gave robust location and extent estimation under different noise levels. Epileptic sources were estimated from interictal discharges in drug-resistant epilepsy patients. FAST-IRES outperformed LCMV in both simulation and patient data analysis.

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“…This is largely due to the fact that MEG is less sensitive to deep cortical sources and subcortical sources (Agirre-Arrizubieta et al, 2009; Attal et al, 2009; Ahlfors et al, 2010; Wennberg et al, 2011; Attal and Schwartz, 2013). Deep source localization has long been considered a difficult problem (Hillebrand and Barnes, 2002; Attal et al, 2009), especially given the need for the development of radically new algorithms capable of achieving such a goal (Krishnaswamy et al, 2017; Bénar et al, 2021). Recent attempts have been made to address the issue, but such studies usually require the aid of simultaneous intracranial recordings (Juárez-Martinez et al, 2018; Pizzo et al, 2019; Pellegrino et al, 2020) or prior knowledge of the activation patterns (Krishnaswamy et al, 2017) while large-scale validation is still not available.…”

Section: Discussionmentioning

confidence: 99%

Imaging the extent and location of spatiotemporally distributed epileptiform sources from MEG measurements

Jiang

Sohrabpour

et al. 2021

Preprint

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Non-invasive MEG/EEG source imaging provides valuable information about the epileptogenic brain areas which can be used to aid presurgical planning in focal epilepsy patients suffering from drug-resistant seizures. However, the source extent estimation for electrophysiological source imaging remains to be a challenge and is usually largely dependent on subjective choice. Our recently developed algorithm, fast spatiotemporal iteratively reweighted edge sparsity minimization (FAST-IRES) strategy, has been shown to objectively estimate extended sources from EEG recording, while it has not been applied to MEG recordings. In this work, through extensive numerical experiments and real data analysis in a group of focal drug-resistant epilepsy patients’ interictal spikes, we demonstrated the ability of FAST-IRES algorithm to image the location and extent of underlying epilepsy sources from MEG measurements. Our results indicate the merits of FAST-IRES in imaging the location and extent of epilepsy sources for pre-surgical evaluation from MEG measurements.

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Detection and localization of deep sources in magnetoencephalography: A review

Cited by 15 publications

References 74 publications

Functional Interactions between Entorhinal Cortical Pathways Modulate Theta Activity in the Hippocampus

Functional Interactions between Entorhinal Cortical Pathways Modulate Theta Activity in the Hippocampus

Imaging the extent and location of spatiotemporally distributed epileptiform sources from MEG measurements

Imaging the extent and location of spatiotemporally distributed epileptiform sources from MEG measurements

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