The in vitro isolated whole guinea pig brain as a model to study epileptiform activity patterns

Background: Research on ictogenesis is based on the study of activity between seizures and during seizures in animal models of epilepsy (chronic condition) or in in vitro slices obtained from naive non-epileptic brains after treatment with pro-convulsive drugs, manipulations of the extracellular medium and specific stimulation protocols. New method: The in vitro isolated guinea pig brain retains the functional connectivity between brain structures and maintains interactions between neuronal, glial and vascular compartments. It is a close-to in vivo preparation that offers experimental advantages not achieved with the use of other experimental models. Neurophysiological and imaging techniques can be utilized in this preparation to study brain activity during and between seizures induced by pharmacological or functional manipulations. Results: Cellular and network determinants of interictal and ictal discharges that reproduce abnormal patterns observed in human focal epilepsies and the associated changes in extracellular ion and blood brain permeability can be identified and analyzed in the isolated guinea pig brain. Comparison with existing methods: Ictal and interictal patterns recorded in in vitro slices may show substantial differences from seizure activity recorded in vivo due to slicing procedure itself. The isolated guinea pig brain maintained in vitro by arterial perfusion combines the typical facilitated access of in vitro preparations, that are difficult to approach during in vivo experiments, with the preservation of larger neuronal networks. Conclusions: The in vitro whole isolated guinea pig brain preparation offers an unique experimental model to study systemic and neurovascular changes during ictogenesis. Published by Elsevier B.V.