Fig. 7.
Depolarization-induced changes in G in low vs. high input conductance cells. A: examples of shift in G with depolarization. Upper cell (gray trace) is from low end of input conductance range (0.5 μS), whereas lower cell (black trace) is at high end of input conductance range (1.86 μS). Although both cells exhibit similar shifts in G at low frequencies, they diverge dramatically as frequency increases. B: comparison of relative I-V curvature at 12.5 vs. 125 Hz. In 9 cells where 2 protocols were run close to the threshold voltage, the normalized I-V curvature (i.e., ΔG/ΔV/GN) was determined and compared at 12.5 and 125 Hz. As shown, there is a relatively larger downward I-V curvature in lower conductance cells at lower frequencies compared with higher input conductance cells, which have larger downward I-V curvature at higher frequencies.