Computational modeling demonstrates that encoding and context-dependent retrieval of memories in region CA1 of the hippocampus will be most effective when the phase of strongest entorhinal input (to stratum lacunosum-moleculare) is offset from the phase of maximal induction of long-term potentiation at Schaffer collateral synapses (in stratum radiatum). This would allow entorhinal input to play a role in both retrieval and encoding without engaging LTP during retrieval. Experiments in brain slice preparations of the hippocampal formation tested the relationship between rhythmic input to stratum lacunosum-moleculare and the time of maximal LTP induction at Schaffer collateral synapses in stratum radiatum. Analysis of the data demonstrates a statistically significant difference in the induction of LTP for different time intervals between the end of each four pulse train in s. l-m and the single pulse s. rad stimulation. The time of maximal LTP induction was found to be about 30 msec after the end of lacunosum-moleculare stimulation, consistent with the requirements of the model.