fEPSPs in CA3 stratum lucidum were induced by stimulation of mossy fibers in acute hippocampal slices. (A) Representative fEPSP traces from slices of 4-8-month-old mice. (B, C) Input/output curves reflecting the change in the fEPSP slope as a function of the fiber volley amplitude from slices obtained at 4-8 (B) or 20 (C) months of age. (D, E) Short-term plasticity assessed by measuring the PPR (second pulse/first pulse) with 50-msec interpulse interval at 4-8 (D) or 20 (E) months of age. 