Heterosynaptic depression: a postsynaptic correlate of long-term potentiation

BRIEF trains of electrical stimulation delivered to any one of several hippocampal pathways often result in immediate and long-lasting enhancement of subsequent postsynaptic responses elicited by that pathway1–5. The unusual characteristics of these effects suggest that theories of long-term potentiation (specifically changes in transmitter release by the presynaptic terminal) which have evolved from work on invertebrate and neuromusclar preparations may not be appropriate to explain synaptic plasticity in hippocampus. We report here the results of experiments intended to examine the postsynaptic consequences of repetitive stimulation. We found that potentiation of one afferent tended to depress the target cell's responses to a second test input.