Magnetoencephalographic signatures of insular epileptic spikes based on functional connectivity

Abstract

Failure to recognize insular cortex seizures has recently been identified as a cause of epilepsy surgeries targeting the temporal, parietal, or frontal lobe. Such failures are partly due to the fact that current noninvasive localization techniques fare poorly in recognizing insular epileptic foci. Our group recently demonstrated that magnetoencephalography (MEG) is sensitive to epileptiform spikes generated by the insula. In this study, we assessed the potential of distributed source imaging and functional connectivity analyses to distinguish insular networks underlying the generation of spikes. Nineteen patients with operculo-insular epilepsy were investigated. Each patient underwent MEG as well as T1-weighted magnetic resonance imaging (MRI) as part of their standard presurgical evaluation. Cortical sources of MEG spikes were reconstructed with the maximum entropy on the mean algorithm, and their time courses served to analyze source functional connectivity. The results indicate that the anterior and posterior subregions of the insula have specific patterns of functional connectivity mainly involving frontal and parietal regions, respectively. In addition, while their connectivity patterns are qualitatively similar during rest and during spikes, couplings within these networks are much stronger during spikes. These results show that MEG can establish functional connectivity-based signatures that could help in the diagnosis of different subtypes of insular cortex epilepsy. Hum Brain Mapp 37:3250-3261, 2016. © 2016 Wiley Periodicals, Inc.

Dissociated cortical phase- and amplitude-coupling patterns in the human brain

“…Both coupling modes may provide versatile biomarkers for various neuropsychiatric diseases (Fornito et al, 2015;Stam, 2014) including autism (Kitzbichler et al, 2015), schizophrenia (Cetin et al, 2016;Maran et al, 2016), epilepsy (Burns et al, 2014;van Dellen et al, 2014;Zerouali et al, 2016), dementia (Koelewijn et al, 2017;Maestú et al, 2015), Parkinson's disease (Oswal et al, 2016), multiple sclerosis (Cover et al, 2006;Schoonheim et al, 2013;Tewarie et al, 2014) and blindness (Hawellek et al, 2013).…”

Cortical thickness analysis in operculo-insular epilepsy

“…In addition, the anterior and posterior insulae seem to present a differential pattern of connectivity. Various functional and structural connectivity studies have shown that the anterior insula is highly linked to the anterior cingulate gyrus, the orbitofrontal cortex and the prefrontal area whereas the posterior insula is more connected to the perirolandic, parietal and temporoparietal cortices ( Almashaikhi et al, 2014 ; Cauda et al, 2012 ; Cerliani et al, 2012 ; Deen et al, 2011 ; Ghaziri et al, 2017 ; Zerouali et al, 2016 ).In our study, the epileptogenic focus involved either the anterior, posterior, or the whole extent of the insula. It is therefore conceivable that foci within different subregions of the insula might have resulted in distinctive connectivity-related distributions of atrophy.…”

Large-Scale Desynchronization During Interictal Epileptic Discharges Recorded With Intracranial EEG

“…In order to identify the time windows during which the global PLV-based synchrony level departs significantly from chance level, we designed a band-specific nonparametric statistical procedure. First, electrode signals were randomly shuffled across IEDs, such that electrode signal X i,k from electrode i and IED k is replaced by the signal X i,l , where l is a IED index and k = l. This procedure disrupts the connectivity structure among sensors while preserving the IED shape (39). Dynamics of global connectivity is then computed using the procedure described in the previous section.…”