title: Coalescence of deep and superficial epileptic foci into larger discharge units in adult rat neocortex.
abstract: Epilepsy is a disease of neuronal hyper-synchrony that can involve both neocortical and hippocampal brain regions. While much is known about the network properties of the hippocampus little is known of how epileptic neocortical hyper-synchrony develops. We aimed at characterizing the properties of epileptic discharges of a neocortical epileptic focus. We established a multi-electrode-array method to record the spatial patterns of epileptiform potentials in acute adult rat brain slices evoked by 4-Aminopyridine in the absence of magnesium. Locations of discharges mapped to two anatomical regions over the somatosensory cortex and over the lateral convexity separated by a gap at a location matching the dysgranular zone. Focal epileptiform discharges were recorded in superficial and deep neocortical layers but over superficial layers, they exhibited larger surface areas. They were often independent even when closely spaced to one another but they became progressively coupled resulting in larger zones of coherent discharge. The gradual coupling of multiple, independent, closely spaced, spatially restricted, focal discharges between deep and superficial neocortical layers represents a possible mechanism of the development of an epileptogenic zone.
authors.affiliation: Department of Neurology, University of Utah, Clinical Neuroscience Center, Salt Lake City, UT, United States; George E. Wahlen VA Medical Center, Salt Lake City, UT, United States. Electronic address: ruggero.serafini@yahoo.com.
authors.forename: Ruggero
authors.initials: R
authors.lastname: Serafini
authors.affiliation: Department of Pharmacology, Wayne State University, Detroit, MI, United States.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Andrade
authors.affiliation: Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI, United States; Department of Neurology and Rehabilitation, University of Illinois at Chicago, Chicago, IL, United States.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Loeb
mesh_terms: D015761:4-Aminopyridine; D000818:Animals; D004827:Epilepsy / Q000503:physiopathology*; D004867:Equipment Design; D008275:Magnesium Deficiency; D008839:Microelectrodes; D051381:Rats; D013003:Somatosensory Cortex / Q000503:physiopathology*; D046509:Tissue Culture Techniques
chemical_list: D015761:4-Aminopyridine
keywords: early development of a focus; epileptic discharges; neocortical focus