(A) 1-A.3 Steady-state current/voltage curves show that net outward currents grow in three age bins (P1-P5; P6-9; and P10-P16). Small and large currents are evident in all age ranges. (B,D and F) Log-normal plots showing the distribution of maximum conductance (gmax), current threshold (Ithreshold) and latency in three age bins, respectively. Points are color coded to indicate normalized basal position (red to blue gradient), unlabeled cells (gray) and type II neurons (black). Within each age bin, biophysical properties of type I SGN change as a gradient along the NBP scale. The relative dispersion in each distribution is quantified by the CV (coefficient of variation indicated above each distribution) and is not systematically dependent on age. C,E and F Plots of same three features, gmax, current threshold, and latency plotted with age as a continuous variable but with spatial position binned as ‘modiolar-contacting’ (NBP >0; red symbols) and ‘pillar-contacting’ (NBP <= 0, blue symbols). Solid lines in C and E show the best regression fits through modiolar-contacting and pillar-contacting groups . Solid lines in F plot curves defined by the inverting the regression plots in C; .