Fig. 7.

Depression in the presence of CPPG. Trains of 30 stimuli at 5 or 10 Hz were applied at intervals of ≈45 sec. After four to five examples of depression in control conditions were obtained, 300 μm CPPG was perfused into the slice.A, I₀ andI_ss for each train were normalized to the corresponding average values of the control group and plotted as a function of the number of trains. Note that, after 300 μmCPPG was applied (indicated by the solid bar),I_ss was increased to 1.25-fold over control, whereas I₀ was unaffected (n = 4 cells). B, For a single cell the average depression under control conditions (n= 4 trains; open symbols) is superimposed on the average depression in the presence of 300 μm CPPG (n = 4 trains; closed symbols). Note that I₀ is unchanged, whereas the decrement in EPSC amplitude induced by depression (I_d) is slightly reduced by 300 μm CPPG.