Effects of kainic acid microinfusions on hippocampal type 2 RSA (theta)

This study investigated the effects of bilateral, selective lesions of subfield CA3, produced by intrahippocampal administration of kainic acid, on the generation of hippocampal type 2 RSA. Within 4 weeks of lesioning, animals were anesthetized with urethane and microelectrode depth profiles were performed throughout the dorsal-ventral extent of the hippocampus. In control animals, spontaneous and stimulation-induced RSA was present at the amplitude maxima in stratum oriens of the CA1 and at the level of the hippocampal fissure. Animals that received intrahippocampal microinfusions of kainic acid showed a significant reduction of RSA amplitude at both the stratum oriens and fissure regions. These results suggest that the CA3 subfield may play an important role in the production of type 2 RSA.