The pre/post LTP debate.

The pre/post debate involves the question of whether long-term potentiation (LTP) is mediated by enhancement of release, enhancement of postsynaptic receptors, or both. Recent papers have presented evidence for purely postsynaptic or purely presynaptic changes, and a paper by Ahmed and Siegelbam (in this issue of Neuron) suggests a mechanism by which release is enhanced. This debate is increasingly constrained by technical advances that allow central synapses to be studied with increasing precision. A possible of way of reconciling conflicting evidence is suggested.