Figure 5.

Response enhancement by two-pip stimuli in nonlinear A1 neurons. A, Nonlinear neurons were not responsive to tones (median = 0 spikes/s, gray histogram). However, using two-pip stimuli, we could drive these neurons to a median of 24 spikes/s (black histogram), comparable to the median pure tone response (at BF) of tone-responsive neurons in the awake marmoset. (**p < 0.01; Wilcoxon rank-sum test). B, When we quantified degree of nonlinearity (see Materials and Methods), we observed a median 250% facilitation over the sum of linear components. C, Histograms of precision in frequency and time of the second-order subunits (half-maximal extent). Median spectral and temporal precision were 0.125 oct. and 12.5 ms respectively.