ABSTRACT
Fenwick and Brown (1989) adopt a model whereby epileptic seizures are precipitated or inhibited depending upon the relative excitation of groups of neurones in and around the damaged area of brain. Group One (G1) neurones, at the centre of an epileptic focus, are damaged and show continuously abnormal patterns of activity. Surrounding these are Group Two (G2) neurones, which are only partially damaged and function either normally or abnormally in terms of paroxysmal epileptic activity. During a focal seizure, G1 neurones recruit G2 neurones into their abnormal pattern of activity. If G2 neurones then recruit normal neurones into their abnormal firing, the seizure generalises. Fenwick and Brown (ibid.) state that the level of electrophysiological activation of G2 neurones, and of normal brain tissue surrounding the focus, determines whether seizure activity is subsequently inhibited or enhanced. There appears to be a relationship between behavioural, physiological and psychological states and the probability of seizure occurrence such that seizures do not occur in a vacuum (ibid.).
