From some sources, I've read that excitatory postsynaptic potentials (EPSPs) decay over time, which would imply that they aren't abolished by action potentials. However, other sources seem to indicate the opposite (although I may be misunderstanding them). Plus, the classical leaky-integrate-and-fire neuron model implies that EPSPs are abolished by action potentials (although this could well be a simplification). Does the refractory period of an action potential affect its originating EPSP? Or is it a separate phenomenon?
While model neurons like the leaky integrate and fire may use a simplification in which the neuron forgets all previous information when it emits a spike, in a biological neuron, the synapse and the soma are relatively electrically isolated from each other, so the voltage activity of the action potential does not make the synapse "forget" the EPSP. Although see back propagating action potentials for a mechanism for somatic action potentials to affect dendritic processing. (http://www.ncbi.nlm.nih.gov/pubmed/8107777)