Figure 2.

Depression of GABAergic transmission. (A) Upper, Superimposed traces showing the monosynaptic GABAergic PSC elicited on its own (thin line) or after a high-frequency burst delivered via the distal electrode (thick line). The depression (1) is abolished by addition of DNQX to the perfusion solution (2). Lower, Proximal PSC amplitude plotted against time for the same experiment. APV and GYKI52466 were present throughout, to block NMDA and AMPA receptors. The traces in A were obtained by averaging 10 records under each condition, at the times indicated. Horizontal lines indicate the average amplitudes of the test and conditioned PSC before and during DNQX perfusion. Picrotoxin (100 μM) abolished the PSC, indicating that it was mediated by GABA_A receptors. (B) Average of 11 experiments. The PSC amplitudes were normalized to set the average amplitude of the unconditioned response to 100%. Each point shows the average of 2–4 successive trials. DNQX completely abolished the depression of inhibition.