The Relationship Between Ictal Multi-Unit Activity and the Electrocorticogram

Int J Neural Syst. 2018 Dec;28(10):1850027. doi: 10.1142/S0129065718500272. Epub 2018 Jun 18.

Abstract

During neocortical seizures in patients with epilepsy, microelectrode array recordings from the ictal core show a strong correlation between the fast, cellular spiking activities and the low-frequency component of the potential field, reflected in the electrocorticogram (ECoG). Here, we model the relationship between the cellular spike activity and this low-frequency component as the input and output signals of a linear time invariant system. Our approach is based on the observation that this relationship can be characterized by a so-called sinc function, the unit impulse response of an ideal (brick-wall) filter. Accordingly, using a brick-wall filter, we are able to convert ictal cellular spike inputs into an output that significantly correlates with the observed seizure activity in the ECoG (r = 0.40 - 0.56,p < 0.01) , while ECoG recordings of subsequent seizures within patients also show significant, but lower, correlations (r = 0.10 - 0.30,p < 0.01) . Furthermore, we can produce seizure-like output signals using synthetic spike trains with ictal properties. We propose a possible physiological mechanism to explain the observed properties associated with an ideal filter, and discuss the potential use of our approach for the evaluation of anticonvulsant strategies.

Keywords: Seizure; epilepsy; ideal filter; spike train.

MeSH terms

  • Action Potentials / physiology*
  • Adult
  • Brain / pathology*
  • Brain / physiopathology*
  • Brain Waves / physiology*
  • Electroencephalography
  • Epilepsy / pathology
  • Epilepsy / physiopathology*
  • Female
  • Humans
  • Models, Neurological
  • Neurons / physiology*
  • Nonlinear Dynamics
  • Young Adult