Neuron
Volume 15, Issue 2, August 1995, Pages 427-434
Journal home page for Neuron

Article
Evidence for silent synapses: Implications for the expression of LTP

https://doi.org/10.1016/0896-6273(95)90046-2Get rights and content
Under an Elsevier user license
open archive

Abstract

Recent work has suggested that some proportion of excitatory synapses on hippocampal CA1 pyramidal cells that express NMDA receptors (NMDARs) may not express functional AMPA receptors (AMPARs), thus making these synapses silent at the resting membrane potential. In agreement with this hypothesis, we demonstrate here that it is possible to stimulate synapses that yield no detectable excitatory postsynaptic currents (EPSCs) when the cell is held at −60 mV; yet at positive holding potentials (+30 to+60 mV), EPSCs can be elicited that are completely blocked by the NMDAR antagonist, D-APV. When these functionally silent synapses are subjected to an LTP induction protocol, EPSCs mediated by AMPARs appear and remain forthe duration of the experiment. This conversion of silent synapses to functional synapses is blocked by D-APV. These results suggest that LTP may involve modification of AMPARs that, prior to LTP, were either not present in the postsynaptic membrane or electrophysiologically silent. This mechanism may account for several experimental results previously attributed to presynaptic changes in quantal content.

Cited by (0)