Faculty Collaboration Database

Multiscale Aspects of Generation of High-Gamma Activity during Seizures in Human Neocortex. eNeuro 2016;3(2)

Date

06/04/2016

Pubmed ID

27257623

Pubmed Central ID

PMC4876490

DOI

10.1523/ENEURO.0141-15.2016

Scopus ID

2-s2.0-85021858529 (requires institutional sign-in at Scopus site)   21 Citations

Abstract

High-gamma (HG; 80-150 Hz) activity in macroscopic clinical records is considered a marker for critical brain regions involved in seizure initiation; it is correlated with pathological multiunit firing during neocortical seizures in the seizure core, an area identified by correlated multiunit spiking and low frequency seizure activity. However, the effects of the spatiotemporal dynamics of seizure on HG power generation are not well understood. Here, we studied HG generation and propagation, using a three-step, multiscale signal analysis and modeling approach. First, we analyzed concurrent neuronal and microscopic network HG activity in neocortical slices from seven intractable epilepsy patients. We found HG activity in these networks, especially when neurons displayed paroxysmal depolarization shifts and network activity was highly synchronized. Second, we examined HG activity acquired with microelectrode arrays recorded during human seizures (n = 8). We confirmed the presence of synchronized HG power across microelectrode records and the macroscale, both specifically associated with the core region of the seizure. Third, we used volume conduction-based modeling to relate HG activity and network synchrony at different network scales. We showed that local HG oscillations require high levels of synchrony to cross scales, and that this requirement is met at the microscopic scale, but not within macroscopic networks. Instead, we present evidence that HG power at the macroscale may result from harmonics of ongoing seizure activity. Ictal HG power marks the seizure core, but the generating mechanism can differ across spatial scales.

Author List

Eissa TL, Tryba AK, Marcuccilli CJ, Ben-Mabrouk F, Smith EH, Lew SM, Goodman RR, McKhann GM Jr, Frim DM, Pesce LL, Kohrman MH, Emerson RG, Schevon CA, van Drongelen W

Author

Sean Lew MD Chief, Professor in the Neurosurgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adolescent
Child
Child, Preschool
Drug Resistant Epilepsy
Electric Stimulation
Electroencephalography
Evoked Potentials
Female
Gamma Rhythm
Humans
In Vitro Techniques
Male
Microelectrodes
Neocortex
Patch-Clamp Techniques