Fig. 4.

Endogenous release of l-glutamate from the postsynaptic cell induced a depression of unitary IPSCs.A, B, Plot of the peak amplitude of the first IPSCs throughout experiments during which unitary synaptic responses were elicited in pyramidal cells alternatively in control conditions (control) and 900 msec after a conditioning depolarization of the postsynaptic pyramidal cells (conditioning). Insets illustrate the average unitary IPSCs elicited by pairs (A) or trains (B) of APs at different epochs of the experiments. Conditioning protocols with standard intracellular solution (A) or in the presence of QX-314 in the patch pipette (B) induced a decrease of the unitary IPSCs, which was prevented after subsequent addition of CNQX.