Figure 2.

Possibly dynamical scenario of recurrent episodes as a cycle (a)–(d) in chronic disorders (disease state) vs normal state (e) described in pictorial ‘landscapes’. (a) interictal: stable state where the disease under control; (b) prodrome: when the state escapes over the potential barrier to a relative flat plateau, the transient meta stable state is characterised by a strongly fluctuating and correlated subnetwork (cf. Figure 1); (c) ictal: at a certain point, the episodes manifest in form of a transient excursion that is recovered in (d) postdrome (possibly changed landscape); (e) normal state remains stable because the potential barrier toward the ictal state is too high. (f ) Additional premonitory symptoms such as migraine aura or aura in epilepsy indicates the existence of different plateaus (cf. Figure 3). (g) Chronification of diseased state: landscape changes such that the attack state persists.