Organophosphorus Anticholinesterase-Induced Epileptiform Activity in the Hippocampus
In the study of epileptogenesis, the pharmacological induction of convulsant activity has provided important information regarding the cellular events involved in the production of abnormal electrical discharges. This research approach has benefited from the advent of in vitro central nervous system (CNS) tissue slices and the use of microelectrode recording techniques (Yamamoto, 1972). Synchronous repetitive discharges induced by the drugs examined thus far are the characteristic features of the epileptiform activity recorded in vivo and in vitro. These discharges are considered to be correlated with abnormal interictal electroencephalographic (EEG) recordings (Ayala et al., 1973). The corresponding intracellular event is comprised of a series of action potentials superimposed on an envelope of depolarization. This envelope of depolarization was termed the paroxysmal depolarizing shift (PDS) by Matsumoto and Ajmone Marson (196M) in characterizing penicillin-induced discharges in vivo. Recent studies have shown that the event underlying the drug-induced PDS is a net excitatory response produced by a synchronous synaptic input (Johnston and Brown, 1981; Lebeda et al., 1982).
KeywordsReversal Potential Epileptiform Activity Discharge Frequency Extracellular Recording Inhibitory Synaptic Transmission
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