Fig. 3.

Contra-noise suppression persists after a strychnine dose that blocks shock-evoked medial olivocochlear (MOC) suppression. A: in 1 animal, shock-evoked and contra-noise-evoked effects were both measured before and after systemic strychnine (10 mg/kg). Strychnine blocked shock-evoked suppression (filled triangles, mean of 3 runs), leaving only a slow enhancement (open triangles, mean of 2 runs) as described in a prior report (Maison et al. 2007), while producing little effect on contra-noise suppression (filled vs. open circles, mean of 3 runs each). B: mean (±SE) effects of strychnine at 10 mg/kg, as measured 30 min after injection (mean of 59 runs from 39 animals). Mean contra-noise level was 102 dB SPL, ipsilateral f₂ was at 16 kHz, and primary levels were set to produce a DPOAE of 0 dB SPL. Key in A applies to both panels.