Neuronal activities in epileptogenic foci of immature cortex

David A. Prince*, Michael J. Gutnick

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

Extracellular and intracellular recordings were obtained from neurons of penicillin-induced epileptogenic foci of kittens aged 3-16 days in order to examine the electrophysiological properties of neurons which might account for the decreased seizure susceptibility in immature cortex. Surface interictal discharges were associated with depolarizations in neurons; however, synaptic depolarizations and surface interictal discharges were longer in duration and more variable in amplitude in the kitten focus than in the focus of mature cortex. During depolarizations most neurons generated bursts of 1-5 spikes at a frequency of 100/sec or less. This behavior was in marked contrast to that seen in mature neurons of a penicillin focus where stereotyped long bursts of high frequency spike discharge accompany each depolarization shift. Spike potentials were long in duration, perhaps accounting for the relatively low frequency output of most neurons during interictal discharges. Prolonged IPSPs were generated in the cells of the focus, even at times when no epileptiform discharge was noted. IPSP generation did not account for the rapid attenuation of triggered epileptiform discharges and depolarizations which occurred at stimulus intervals of 2.5 sec or longer. Asynchrony of activities in the epileptic neuronal aggregate was evidenced by the occurrence of isolated depolarization shifts in some cells and a marked variability both in the size of cellular depolarizations and in their relationships to the surface discharges. The data suggest that asynchrony of activities in the population reduced capacity for high frequency spike generation, and failure of excitatory electrogenesis at relatively low frequencies all contribute to the decreased seizure susceptibility of immature cortex.

Original languageEnglish
Pages (from-to)455-468
Number of pages14
JournalBrain Research
Volume45
Issue number2
DOIs
StatePublished - 27 Oct 1972
Externally publishedYes

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