A study of multi-site brain dynamics during limbic seizures

Neuronal populations in the brain achieve levels of synchronous electrophysiological activity as a consequence of both normal brain functions as well as during pathological states such as in epileptic seizures. Understanding the nature of this synchrony and the dynamics of neuronal oscillators in the brain is a critical component towards decoding such complex behaviors. We have sought to achieve a more in-depth understanding of the dynamics underlying the evolution of seizures in limbic epilepsy by analyzing recordings of local field potentials from three subcortical nuclei that are part of the circuit of Papez in a kainic acid rat model of temporal lobe epilepsy using the empirical mode decomposition technique. The empirical mode decomposition allows for an adaptive and nonlinear decomposition of the local field potentials into a series of finite oscillatory components. We calculated the frequencies, power, and measures of phase synchrony of these oscillatory components as seizures evolve in the brain and discovered patterns of phase synchrony that varies between the different stages of the seizures.