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PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1995-1-24
pubmed:abstractText
To find general principles in the cellular mechanisms of epileptogenesis, one must analyze experimental epilepsy models and determine what exists in common between them. We consider here afterdischarges in hippocampal slices induced using either (1) GABAA blockade (e.g. with bicuculline), (2) a bathing solution lacking Mg2+ ions (low Mg-induced epilepsy), or (3) 4-aminopyridine (4AP). By 'afterdischarge' we mean an event that lasts hundreds of milliseconds or more, involving the synchronous firing of all the neurons in a population, shaped into a long initial burst and a series of one or more secondary bursts, and terminating in a prolonged afterhyperpolarization (AHP). We propose that the following features exists in common between these three experimental epilepsies: (1) recurrent excitatory synaptic connections; (2) sustained dendritic synaptic excitation, mediated by either AMPA or NMDA receptors, or both; (3) an intrinsic cellular response to sustained excitation, consisting of rhythmical dendritic bursts, primarily mediated by Ca spikes. In conclusion, if the picture outlined here proves correct, then the stereotypic appearance of epileptic afterdischarges--consisting of synchronized population bursts in series, whatever the network alteration leading to seizures--does indeed reflect a common set of mechanisms. The mechanisms cannot, apparently, be formulated in simple terms of this receptor or that receptor. Rather, we suggest, the recurrent excitatory synapses are able, under diverse circumstances, collectively to produce sustained dendritic conductances in neuronal populations. Pyramidal neurons, by virtue of their normal intrinsic membrane properties, respond to such sustained conductances with rhythmical bursts. The recurrent synapses, in a dual role, serve to maintain the synchrony of these bursts, and so shape the activity into a synchronized oscillation.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:issn
0079-6123
pubmed:author
pubmed:issnType
Print
pubmed:volume
102
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
383-94
pubmed:dateRevised
2009-9-29
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Are there unifying principles underlying the generation of epileptic afterdischarges in vitro?
pubmed:affiliation
IBM, T.J. Watson Research Center, Yorktown Heights, NY 10598.
pubmed:publicationType
Journal Article, In Vitro, Review, Research Support, Non-U.S. Gov't