  There is increasing evidence for specific cortical and subcortical
large-scale human epileptic networks to be involved in the generation, spread,
and termination of not only primary generalized but also focal onset seizures.
The complex dynamics of such networks has been studied with methods of analysis
from graph theory. In addition to investigating network-specific
characteristics, recent studies aim to determine the functional role of single
nodes---such as the epileptic focus---in epileptic brain networks and their
relationship to ictogenesis. Utilizing the concept of betweenness centrality to
assess the importance of network nodes, previous studies reported the epileptic
focus to be of highest importance prior to seizures, which would support the
notion of a network hub that facilitates seizure activity. We performed a
time-resolved analysis of various aspects of node importance in epileptic brain
networks derived from long-term, multi-channel, intracranial
electroencephalographic recordings from an epilepsy patient. Our preliminary
findings indicate that the epileptic focus is not consistently the most
important network node, but node importance may drastically vary over time.
