Figure 3. Gradual and variable recovery of auditory processing following a massive, bilateral loss of cochlear afferent nerve fibers can be predicted from early changes in inhibitory strength.
Plotting conventions follow Figure 2. (A) Ouabain was applied bilaterally to the round window membrane. (B) Mean ± SEM ABR thresholds were substantially elevated 30 days after ouabain application (left) but DPOAE thresholds were unaffected, indicating normal outer hair cell function (middle). ABR wave1b was virtually eliminated after ouabain (right). Darker and lighter shading represent measurements from mice that recovered cortical sound thresholds versus mice that did not, respectively. (C–D) Rasters document changes in noise-evoked spiking and laser-induced inhibition, respectively, from single A1 RS units recorded over a 53-day period from a mouse that eventually recovered function (C) and a mouse that did not recover function (D). (E–H) Mean ± SEM noise-evoked thresholds (E), rate-level function gain (F), spontaneous firing rate (G) and inhibition strength (H) for all units recorded from three mice that recovered (top row, n = 156), three mice that did not recover (middle row, n = 169) or three mice that underwent a sham surgery (bottom row, n = 156). Asterisks = post-hoc pairwise comparison between identified groups (B) or to baseline value (E–H) p<0.05 after correcting for multiple comparisons.
Figure 3—figure supplement 1. ABR wave 1 amplitude scales with the degree of auditory nerve damage, but does not vary systematically between mice that recover cortical sound thresholds versus those that do not.
