R. D. Traub, R. Miles, and J. G. R. Jefferys. New data are starting to shed light on the all-important issue of how epileptic events lasting as long as a seizure might be generated. In at least some cases seizure like events can arise from CA3 alone. In the work described here we show that CA3, especially from the ventral hippocampus, generates seizure like events in slices incubated in bicuculline. CA3 needs the hilus of the dentate area attached for this to work.
Gap junctions can contribute to the production of seizure like events.
Here we outline pharmacological evidence for this in the case of the low-Mg model, again within the CA3 region of hippocampal slices. Again the hilus appears to play a key role, but in these experiments we were able to compensate for the removal of the hilus by treatments that enhance gap junctions. Transition to seizures can also occur in CA1. Here we show how this occurs in slices in the low-Mg model. These fast trains of activity look like tetanically evoked gamma rhythms and appear to depend on depolarising GABA potentials.