  Inferring strength and direction of interactions from electroencephalographic
(EEG) recordings is of crucial importance to improve our understanding of
dynamical interdependencies underlying various physiologic and pathophysiologic
conditions in the human epileptic brain. We here use approaches from symbolic
analysis to investigate---in a time-resolved manner---weighted and directed,
short- to long-ranged interactions between various brain regions constituting
the epileptic network. Our observations point to complex spatial-temporal
interdependencies underlying the epileptic process and their role in the
generation of epileptic seizures, despite the massive reduction of the complex
information content of multi-day, multi-channel EEG recordings through
symbolisation. We discuss limitations and potential future improvements of this
approach.
