Figure 2.

LTD expression is correlated with a reduction in NMDAR activity at both CI-AMPAR and CP-AMPAR synapses, but an increase in CV was observed only at CP-AMPAR synapses. A1, Time course of EPSCs recorded at +40 mV (1 and 4) or -60 mV (2, 3, and 5) from a CI-AMPAR synapse. Traces in the top panels are EPSCs recorded at the time points indicated in the dot plot (bottom). In this series of experiments, philanthotoxin (PhTx; 5 μm) was added at the end of the experiment to confirm the Ca²⁺-permeable nature of the synapse being studied. A2, The mean NMDAR-mediated EPSC (measured at 50 msec after the stimulus artifact indicated by the vertical dotted lines in both A1 and B1) is significantly reduced after LTD expression at CI-AMPAR synapses. A3, The mean NMDAR-EPSC CV is unaltered after LTD expression at CI-AMPAR synapses. B1-B3, Corresponding data from CP-AMPAR synapses arranged as described above for CI-AMPAR synapses. B3, Note that in addition to a reduction in the NMDAR-EPSC amplitude, the NMDAR-EPSC CV was significantly increased after LTD expression. ^**p < 0.01.