NMDA Antagonists differentiate epileptogenesis from seizure expression in an in vitro model

Article Abstract:

In order to understand the nature of human epilepsy (seizures), it is important to understand the basic electrical state in which they occur. In epilepsy, abnormal electrical activity in one area of the brain can be propagated to surrounding normal brain cells and networks. A model of seizure development and propagation has been developed using slices of an area deep within the brain, the hippocampus. The slices of rat brain are incubated in appropriate solutions to which test chemicals can be administered. The seizure-like activity is induced by electrical stimulation (induction of electrographic seizure or EGS), and is found to spread to surrounding areas. The pattern of the EGS has been found to resemble those of epileptic seizures that occur in humans. Once invoked, the seizure-like behavior may continue for the life of the slice preparations. This study examines the role of specific cell receptors for N-methyl-d-aspartate (NMDA) and finds that the addition of chemicals which counteract NMDA (antagonists) can prevent the progressive development of an epileptic area of the slices. However, the addition of these antagonists failed to prevent the EGSs which were already initiated. The study suggests an important distinction between the conditions necessary to establish an epileptic condition (epileptogenesis) and those which may be necessary to continue it (seizure expression). This also points to a distinction between the drugs which act to prevent the establishment of a focus (antiepileptogenic drugs) and those which prevent seizure expression (anticonvulsant agents).

Causes of, Epilepsy, Spasms, Spasm, Methyl aspartate, N-methyl-D-aspartate

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Long-term potentiation in the CA1 hippocampus

Article Abstract:

Electrophysiology provides little insight into the processes underlying synaptic transmission and long-term potentiation (LTP) in the CA1 hippocampus. Studies of synaptic transmission and LTP in the hippocampus between single presynaptic neurons are evaluated.

Neural transmission, Synaptic transmission

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How does the brain organize memories?

Article Abstract:

Research on memory loss caused by brain lesions has provided new data on the role of the hippocampus in episodic and semantic memory. A model of complementary memory functions involving the cerebral cortex, parahippocampal region and hippocampus is described.

Physiological aspects, Brain, Memory, Localization (Brain function), Brain damage

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