Figure 2.

Facilitation of excitation and polysynaptic inhibition in juvenile rats. A, Example excitatory (black) and inhibitory (blue) conductances recorded in a CA3 PC in response to granule cell stimulation. For illustrative purposes, the excitatory conductance has been multiplied by −1. The red trace is the calculated linear sum of the excitatory and inhibitory traces. B, Because in a subset of neurons no IPSCs were detected in response to stimulus 1, the excitatory (black circles) and inhibitory (blue squares) charge transfers in response to each stimulus were normalized (Norm) to the response to stimulus 5 and then plotted against stimulus number. C, The ratio of excitatory charge transfer to inhibitory charge transfer, E/I ratio, was calculated for each cell and plotted as a function of stimulus number (gray open circles). Error bars, SEM. D, Plot of the time difference between the onset of the EPSC and the onset of the IPSC. E, The peak amplitude of the excitatory (inward) current was measured from the calculated sum of the EPSC and IPSC (red trace in A). All amplitudes were normalized to the amplitude in response to stimulus 5. Open symbols, individual cells; closed symbols, average ± SEM.