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The synapse-bearing nerve terminals of the opener muscle of the crayfish Procambarus were reconstructed using electron micrographs of regions which had been serially sectioned. The branching patterns of the terminals of excitatory and inhibitory axons and the locations and sizes of neuromuscular and axo-axonal synapses were studied. Excitatory and(More)
Using the whole-cell recording technique, we have examined the slow Ca(2+)-activated afterhyperpolarization (AHP) and its underlying current (IAHP) in hippocampal CA1 neurones of brain slices obtained from mature rats. Specifically we have studied the effects of the anion component of various K+ salts commonly used to make the pipette filling solution that(More)
Small amplitude depolarizations (fast prepotentials, spikelets) recorded in mammalian neurons are thought to represent either dendritic action potentials or presynaptic action potentials attenuated by gap junctions. We have used whole-cell recordings in an in vitro calcium-free model of epilepsy to record spikelets from CA1 neurons of the rat hippocampus.(More)
The existence of hippocampal high-frequency electrical activities (greater than 100 Hz) during the progression of seizure episodes in both human and animal experimental models of epilepsy has been well documented (Bragin A, Engel J, Wilson C L, Fried I and Buzsáki G 1999 Hippocampus 9 137-42; Khosravani H, Pinnegar C R, Mitchell J R, Bardakjian B L,(More)
This study presents a model of chronic, recurrent, spontaneous seizures in the intact isolated hippocampal preparation from mice aged P8-P25. Field activity from the CA1 pyramidal cell layer was recorded and recurrent, spontaneous seizure-like events (SLEs) were observed in the presence of low Mg2+ (0.25 mM) artificial cerebrospinal fluid (ACSF). Hippocampi(More)
Gap junctions (gjs) are increasingly recognized as playing a significant role in seizures. We demonstrate that different types of gap junctional blocking agents reduce the duration of evoked seizure-like primary afterdischarges (PADs) in the rat in vitro CA1 hippocampal pyramidal region, following repetitive tetanization of the Schaffer collaterals.(More)
BACKGROUND High-dose opioid therapy can precipitate seizures; however, the mechanism of such a dangerous adverse effect remains poorly understood. The aim of our study was to determine whether the neuroexcitatory activity of high-dose morphine is mediated by selective stimulation of opioid receptors. METHODS Mice hippocampi were resected intact and bathed(More)
We examined the effects of the benzodiazepine antagonist, flumazenil, on epileptiform discharges evoked in the hippocampal CA1 region in vitro. Application of 100 nM flumazenil did not affect normal synaptic responses; however, flumazenil did depress epileptiform discharges induced by 8 mM [K+]o. Epileptiform discharges induced by the GABAA channel(More)
PURPOSE The antiepileptic effects of benzodiazepine-receptor (BZR) agonists have been well documented. Surprisingly, an antiepileptic effect for the BZR antagonist, flumazenil, has also been described, the mechanism of which is unknown. We investigated the effects of nanomolar concentrations of flumazenil and a structurally dissimilar BZR antagonist,(More)