LTP of the fEPSPs in CA1 area of hippocampal tissues of wild-type and G-CSF-deficient mice with different types of tetanic stimulations. Administration of 10 trains of four pulses (A), a single 100 Hz stimulation (B), or four trains of 100 Hz repeated at intervals of 5 min (C) produced a rapid and stable potentiation in the amplitude of fEPSP, calculated as a percentage of baseline mean response slope. Arrows show the time of tetanic stimulation. The time points given refer to induction of LTP. Note the significant impairment of LTP induction in G-CSF-deficient mice for all different types of LTP induction.