A "Generalized seizure" corresponds to an ictal manifestation whose initial semeiology indicates, or is consistent with, more than minimal involvement of both cerebral hemispheres. A network is a functionally and anatomically connected set of cortical and subcortical brain regions in which activity in any one part affects activity in all others. A system is a group of independent but interrelated elements (networks) comprising a unified whole.
A considerable amount of evidence supports the existence of specific cortical and subcortical networks in the genesis, expression and control of generalized seizures. Animal and human data suggested that the so-called generalized seizures involve selective networks while sparing others. A greater understanding of those systems and networks, thoroughly debated in this book, will ultimately lead to improved targeted therapies for so-called generalized epilepsies.