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Τετάρτη 28 Ιουνίου 2017

Reliable and Elastic Propagation of Cortical Seizures In Vivo

Publication date: 27 June 2017
Source:Cell Reports, Volume 19, Issue 13
Author(s): Michael Wenzel, Jordan P. Hamm, Darcy S. Peterka, Rafael Yuste
Mapping the fine-scale neural activity that underlies epilepsy is key to identifying potential control targets of this frequently intractable disease. Yet, the detailed in vivo dynamics of seizure progression in cortical microcircuits remain poorly understood. We combine fast (30-Hz) two-photon calcium imaging with local field potential (LFP) recordings to map, cell by cell, the spread of locally induced (4-AP or picrotoxin) seizures in anesthetized and awake mice. Using single-layer and microprism-assisted multilayer imaging in different cortical areas, we uncover reliable recruitment of local neural populations within and across cortical layers, and we find layer-specific temporal delays, suggesting an initial supra-granular invasion followed by deep-layer recruitment during lateral seizure spread. Intriguingly, despite consistent progression pathways, successive seizures show pronounced temporal variability that critically depends on GABAergic inhibition. We propose an epilepsy circuit model resembling an elastic meshwork, wherein ictal progression faithfully follows preexistent pathways but varies flexibly in time, depending on the local inhibitory restraint.

Graphical abstract

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Teaser

Wenzel et al. map cortical seizure spread at cellular resolution in vivo, and they show that seizures spread reliably, with repeated cell-wise and layer-wise recruitment patterns, yet with greatly variable recruitment durations in absolute time. This elasticity is controlled by inhibitory interneurons, as local GABAA-R blockade abolishes the phenomenon.


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