Effects of increase in membrane potential, membrane conductance, and noise on neuronal responsiveness. A, Depolarization of the membrane potential with the intracellular injection of current results in a leftward shift in the input-output response, a decrease in latency, and a decrease in jitter of spike responses. B, Increasing the background membrane conductance (with the dynamic clamp system) from 0 to 40 nS results in a shift of the input-output relation to the right, an increase in latency, and an increase in spike jitter. C, Increases in the variance of the membrane potential (noise) result in a change in the slope and a “smoothing” of the input-output relation. There is also a decrease in spike latency and jitter for lower-amplitude artificial EPSPs. noise 0, No additional noise (although the baseline conductance for the noise is active); noise 1, increases in the SD of both g_e and g_i to 1 nS; noise 2, increase of these SDs to 2 nS.