Mean growth functions for the eCAP amplitude in chronic animals.

<p>A. Amplitude of the eCAP (P2-N2 wave) as a function of the injected charges recorded in the same animal from one to five weeks after surgery with the PA strategy. Note that the eCAP amplitude largely decreased from the first to the second week post-surgery. During the subsequent weeks, it did not change significantly (p-values>0.05, paired t-test). B. Average growth function of eCAP amplitudes from all chronic animals (mean ± SEM) for the pulse amplitude (PA, blue) or pulse duration (PD, red) coding strategy. Thresholds (indicated by stars) were defined as the charge levels which triggered a response significantly larger than noise level (paired-t tests p<0.05; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0201771#sec002" target="_blank">Methods</a>). The pulse duration strategy gave a higher threshold but no statistical differences were observed in the slope of the growth function and the level of the saturation plateau.