Permittivity coupling across brain regions determines seizure recruitment in partial epilepsy.
Brain regions generating seizures in patients with refractory partial epilepsy are referred to as the epileptogenic zone (EZ). During a seizure, paroxysmal activity is not restricted to the EZ, but may recruit other brain regions and propagate activity through large brain networks, which comprise brain regions that are not necessarily epileptogenic. The identification of the EZ is crucial for candidates for neurosurgery and requires unambiguous criteria that evaluate the degree of epileptogenicity of brain regions. To obtain such criteria and investigate the mechanisms of seizure recruitment and propagation, we develop a mathematical framework of coupled neural populations, which can interact via signaling through a slow permittivity variable. The permittivity variable captures effects evolving on slow timescales, including extracellular ionic concentrations and energy metabolism, with time delays of up to seconds as observed clinically. Our analyses provide a set of indices quantifying the degree of epileptogenicity and predict conditions, under which seizures propagate to nonepileptogenic brain regions, explaining the responses to intracerebral electric stimulation in epileptogenic and nonepileptogenic areas. In conjunction, our results provide guidance in the presurgical evaluation of epileptogenicity based on electrographic signatures in intracerebral electroencephalograms.
Aix Marseille Université, Institut de Neurosciences des Systèmes, 13005 Marseille, France and INSERM, UMR 1106, 13005 Marseille, France and timothee.proix@etu.univ-amu.fr viktor.jirsa@univ-amu.fr.
Timothée
T
Proix
Aix Marseille Université, Institut de Neurosciences des Systèmes, 13005 Marseille, France and INSERM, UMR 1106, 13005 Marseille, France and Assistance Publique-Hôpitaux de Marseille, Hôpital de la Timone, Service de Neurophysiologie Clinique, CHU, 13005 Marseille, France.
Fabrice
F
Bartolomei
Aix Marseille Université, Institut de Neurosciences des Systèmes, 13005 Marseille, France and INSERM, UMR 1106, 13005 Marseille, France and Assistance Publique-Hôpitaux de Marseille, Hôpital de la Timone, Service de Neurophysiologie Clinique, CHU, 13005 Marseille, France.
Patrick
P
Chauvel
Aix Marseille Université, Institut de Neurosciences des Systèmes, 13005 Marseille, France and INSERM, UMR 1106, 13005 Marseille, France and.
Christophe
http://orcid.org/0000-0003-3014-1966
C
Bernard
Aix Marseille Université, Institut de Neurosciences des Systèmes, 13005 Marseille, France and INSERM, UMR 1106, 13005 Marseille, France and timothee.proix@etu.univ-amu.fr viktor.jirsa@univ-amu.fr.
Viktor K
VK
Jirsa
D001921:Brain / Q000503:physiopathology*; D058256:Brain Waves; D004828:Epilepsies, Partial / Q000503:physiopathology*; D006801:Humans; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology; D012640:Seizures / Q000503:physiopathology*
Epileptor; connectivity; epilepsy; modeling; seizure propagation; seizure recruitment