Spatial memory following damage to hippocampal CA3 pyramidal cells with kainic acid: impairment and recovery with preoperative training.

The behavioral function of an intrinsic component of the hippocampus was investigated. Neurotoxic lesions of the CA3 region of the hippocampus impaired performance of a spatial memory task, and produced both hyperactivity and hyperreactivity to sensory stimulation. Both the magnitude and duration of these behavioral alterations depended on the amount of preoperative training received, and on the extent and locus of the lesion within the CA3 subfield. This study indicates that the CA3 subfield contributes to the performance of aat least three behavioral functions known to be mediated by the hippocampus. In addition, the lack of enduring deficits in the behavioral tests in which preoperative training was received suggests that, after loss of the CA3 subfield, some mechanism for recovery of function occurs within the hippocampus.