Synaptic strength is modified by the temporal coincidence of synaptic inputs without Back-Propagating Action Potentials (BPAP) in CA1 pyramidal neurons. To clarify the interactive mechanisms related to associative LTP without BPAP, local stimulation (paired stimuli) was applied onto the dendrites by using high-speed laser uncaging stimulating equipment. Spatially, when the spatial distance between paired stimuli was less than 10 micrometer, nonlinear amplification in EPSP summation was observed. Temporally, in the time window (-20 to +20ms), supralinear amplification was observed. These results are closely related to the spatiotemporal-characteristic for the associative LTP without BPAP.