Maintained saturation of hippocampal long-term potentiation does not disrupt acquisition of the eight-arm radial maze.

The present experiment examined the anterograde effect of bilateral saturation of long-term potentiation (LTP) of the rat perforant path-granule cell response on acquisition of the eight-arm radial maze. To ensure maintained saturation, high-frequency stimulation was applied to the perforant path immediately prior to each trial. LTP did not significantly increase the number of trials required for acquisition of the standard eight-arm radial maze task. Furthermore, the magnitude of LTP did not correlate with the rate of acquisition. LTP also did not significantly affect the number of either working or reference memory errors during subsequent training with only four of the eight arms baited; both control and LTP rats made significantly more reference memory than working memory errors, with the number of both types of errors decreasing as training progressed. These results indicate that prior saturation of LTP within the perforant path-dentate granule cell circuit does not affect acquisition of either the reference or working memory components of the radial maze task. The results are discussed in relation to the role of LTP in acquisition of the eight-arm radial maze.