Cortical local and long-range synchronization interplay in human absence seizure initiation.
Brain activity relies on transient, fluctuating interactions between segregated neuronal populations. Synchronization within a single and between distributed neuronal clusters reflects the dynamics of these cooperative patterns. Thus absence epilepsy can be used as a model for integrated, large-scale investigation of the emergence of pathological collective dynamics in the brain. Indeed, spike-wave discharges (SWD) of an absence seizure are thought to reflect abnormal cortical hypersynchronization. In this paper, we address two questions: how and where do SWD arise in the human brain? Therefore, we explored the spatio-temporal dynamics of interactions within and between widely distributed cortical sites using magneto-encephalographic recordings of spontaneous absence seizures. We then extracted, from their time-frequency analysis, local synchronization of cortical sources and long-range synchronization linking distant sites. Our analyses revealed a reproducible sequence of 1) long-range desynchronization, 2) increased local synchronization and 3) increased long-range synchronization. Although both local and long-range synchronization displayed different spatio-temporal profiles, their cortical projection within an initiation time window overlap and reveal a multifocal fronto-central network. These observations contradict the classical view of sudden generalized synchronous activities in absence epilepsy. Furthermore, they suggest that brain states transition may rely on multi-scale processes involving both local and distant interactions.
Amor
Frédérique
F
Laboratoire de Neurosciences Cognitives et Imagerie Cérébrale, CNRS UPR 640, LENA Université Pierre & Marie Curie, Paris VI Hôpital de la Salpêtrière, Paris, France. frederique.amor@gmail.com
Baillet
Sylvain
S
Navarro
Vincent
V
Adam
Claude
C
Martinerie
Jacques
J
Quyen
Michel Le Van
Mle V
D000293:Adolescent; D000328:Adult; D002540:Cerebral Cortex / Q000503:physiopathology*; D003344:Cortical Synchronization; D004832:Epilepsy, Absence / Q000503:physiopathology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D013995:Time