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Dynamics of sensorimotor cortex activation during absence and myoclonic seizures in a mouse model of juvenile myoclonic epilepsy
Author(s) -
Ding Li,
Gallagher Martin J.
Publication year - 2016
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/epi.13493
Subject(s) - juvenile myoclonic epilepsy , epilepsy , electroencephalography , myoclonic epilepsy , ictal , neuroscience , myoclonic jerk , myoclonus , somatosensory system , psychology , electrophysiology , medicine
Summary Objective Generalized epilepsy syndromes often confer multiple types of seizures, but it is not known if these seizures activate separate or overlapping brain networks. Recently, we reported that mice with a juvenile myoclonic epilepsy mutation (Gabra1[A322D]) exhibited both absence and myoclonic generalized seizures. Here, we determined the time course of sensorimotor cortex activation and the spatial distribution of spike voltage during these two seizures. Methods We implanted Gabra1 +/A322D mice with multiple electroencephalography ( EEG ) electrodes over bilateral somatosensory cortex barrel fields (S1) and anterior ( aM 1) and posterior ( pM 1) motor cortices and recorded absence seizures/spike‐wave discharges ( SWD s) and myoclonic seizures. We used nonlinear‐association analyses and cross‐correlation calculations to determine the strength, leading regions, and time delays of cortical coupling from the preictal to ictal states and within the spike and interspike periods. The distribution of spike voltage was also measured in SWD s and myoclonic seizures. Results EEG connectivity among all electrode pairs increased at the onset of both SWD s and myoclonic seizures. Surprisingly, during spikes of both seizure types, S1 led M1 with similar delay times. Myoclonic seizure spikes started more focally than SWD spikes, with a significant majority appearing first only in S1 electrodes, whereas a substantial fraction of SWD spikes were detected first in S1 and at least one M1 electrode. The absolute voltage of myoclonic seizure spikes was significantly higher than that of SWD spikes, and there was a greater relative voltage over M1 during myoclonic seizure spikes than in the first one to two SWD spikes. Significance The leading sites in S1 and similar delay times suggest both SWD s and myoclonic seizures activate overlapping networks in sensorimotor cortex and thus, therapeutically targeting of this network could potentially treat both seizures. Spike focality, absolute voltage, and voltage distribution provide insight into neuronal activation during these two seizure types.