(Proceedings of the National Academy of Sciences, 2012) Kramer, M. A.; Truccolo, W.; Eden, U. T.; Lepage, K. Q.; Hochberg, Leigh; Eskandar, Emad; Madsen, Joseph; Lee, Jong; Maheshwari, A.; Halgren, E.; Chu, Catherine; Cash, Sydney
Why seizures spontaneously terminate remains an unanswered fundamental question of epileptology. Here we present evidence that seizures self-terminate via a discontinuous critical transition or bifurcation. We show that human brain electrical activity at various spatial scales exhibits common dynamical signatures of an impending critical transition—slowing, increased correlation, and flickering—in the approach to seizure termination. In contrast, prolonged seizures (status epilepticus) repeatedly approach, but do not cross, the critical transition. To support these results, we implement a computational model that demonstrates that alternative stable attractors, representing the ictal and postictal states, emulate the observed dynamics. These results suggest that self-terminating seizures end through a common dynamical mechanism. This description constrains the specific biophysical mechanisms underlying seizure termination, suggests a dynamical understanding of status epilepticus, and demonstrates an accessible system for studying critical transitions in nature.
