Figure 7.

Frequency tuning curves of ipsilateral CAP reduction produced by contralateral tones at two intensities in an awake and anesthetized chinchilla. The magnitude and extent of the CAP reduction depend on the contralateral stimulus frequency and intensity. In this case, for a 4 kHz ipsilateral tone (48 dB SPL) the greatest CAP reductions were obtained for contralateral frequencies between 3400 and 4000 Hz. As in all other animals, the efferent effect was better tuned and stronger in awake than in anesthetized condition. Awake vs. anesthetized, 68 dB SPL (Mann-Whitney, U₍₃₂₎ = 0.0, T = 392, p < 0.001), 58 dB SPL (Mann-Whitney, U₍₃₂₎ = 0.0, T = 392, p < 0.001); 68 dB SPL vs. 58 dB SPL, awake (Mann-Whitney, U₍₃₂₎ = 45.0, T = 181, p = 0.002), anesthetized (Mann-Whitney, U₍₃₂₎ = 0.0, T = 136, p < 0.001).