Transfer between chemical and electrical kindling in the septal-hippocampal system.

We re-investigated the interaction between chemical and electrical kindling in two anatomical locations: the amygdaloid region and the septal-hippocampal complex. Amygdaloid animals were implanted with a chemitrode into the left basolateral amygdala, which could then be stimulated electrically (400 microA, 1 s, 60 Hz, AC) or chemically by injection of carbachol (1 microliter, 2.7 nmol, sterile, isotonic). Septal-hippocampal animals were implanted with an electrode high in the medial septum, a cannula in the dorsal hippocampus. In both groups, half the animals were kindled electrically, and after one week of rest chemical kindling was begun. The other half were kindled chemically first, then electrically. The result differed with the anatomical location. With amygdaloid implants, no significant transfer was observed. In the septal-hippocampal group, by contrast, significant interactions were observed in both directions. These results suggest that chemical and electrical kindling involves similar mechanisms, and that the extent to which transfer occurs reflects the degree to which they share a common chemical anatomy.