Figure 3.

Firing rate vs. sound intensity functions after ouabain treatment show elevated thresholds and enhanced gain. (A) Average rate-level functions of all significantly responsive sites (see “Materials and Methods” Section) in the two experimental groups, in response to broadband chirp stimuli. Sp/s = spikes per second. Error bars are mean ± SEM. (B) Minimum thresholds are significantly elevated in the ouabain-treated group (p = 3.75 × 10⁻⁴; Wilcoxon rank sum test; horizontal lines = median). Error bars are median ± interquartile range. (C) The slope of the initial rising segment of rate level functions is significantly enhanced in the ouabain treated group, indicating increased gain (measured as the increase in spiking rate per 5 dB step, p = 0.007, unpaired t-test). Error bars are mean ± standard deviation. (D) Mean probability of correct classification by level in both groups, determined by a peristimulus time histogram (PSTH)-based Euclidean distance classifier (see “Materials and Methods” Section). Classification is considered “correct” within a ±5 dB range. The probability of assigning the correct sound level by chance is indicated by the dashed gray line. Error bars are mean ± SEM. (E) Confusion matrices of level classification in sham (left) and ouabain treated (right) groups, averaged across individual multi-unit sites, with PSTHs binned at 10 ms resolution.