Comparison of the short- and long-lasting effects of perforant path kindling on radial maze learning.

The present experiment compared the long-lasting with the short-lasting effects of kindling the perforant path input to the hippocampal formation on the acquisition of two radial maze tasks. Animals in the long-term group were fully kindled (i.e., Stage 5 motor seizures were evoked) prior to a stimulation-free training period. Animals in the short-term group were kindled 30-45 min prior to each learning trial. A third group of animals served as controls and were never kindled. On both 8-arm and 4/8-arm radical maze tasks, learning impairments were apparent only in the short-term group. Thus, the impaired learning is more likely related to the short-term aftereffects of an afterdischarge than to any long-term alterations in the neuronal status of the brain caused by kindling.