Figure 3.
The compressive shape of modulation input-output functions (MIOFs) partially compensates for the attenuation of AM caused by reverberation. A, MIOF from an IC neuron (BF = 4.2 kHz) for fm = 64 Hz, showing RMD (mean ± 2 SD) as a function of stimulus modulation depth. Thick black line indicates least-squares fit with an incomplete beta function (see Materials and Methods). Green cross represents prediction of reverberant RMD from the MIOF. Red dot indicates measured reverberant RMD. B, MIOF from the same neuron plotted in dB. Dashed line with slope of 1 dB/dB represents identity (0 dB neural modulation gain). The neural modulation gain in the reverberant condition (vertical red arrow) is greater than than the neural modulation gain in the anechoic condition (vertical blue arrow). The difference between reverberant and anechoic modulation gains, or neural compensation, results from the compressive shape of the MIOF (average slope: 0.7 dB/dB).