Interaction between paired-pulse facilitation and long-term potentiation of minimal excitatory postsynaptic potentials in rat hippocampal slices: A patch-clamp study

Long-term potentiation is an experimental paradigm used to study synaptic plasticity and memory mechanisms. One similarity between long-term potentiation and memory is the existence of several distinct phases. However, our preliminary quantal analysis did not reveal essential differences in expression mechanisms of the early (0.5–1 h) periods after tetanus. Calculations of partial correlations and regression analysis indicated that positive correlation between potentiation magnitude and initial (pretetanic) paired-pulse facilitation tended to increase in the late potentiation phase (1.5–2.5 h post-tetanus) indicating that different mechanisms are involved in the early (0.5 h post-tetanus) and the late phase of long-term potentiation. The findings are compatible with involvement of presynaptic mechanisms in both the early and late phases of long-term potentiation. However, the results suggest that contribution of changes in release probability and in effective number of transmitter releas