Figure 6.

Location and properties of nonlinear neurons in A1. A, Distribution of absolute depth (from dural surface) and relative depth (from first neuron encountered) of nonlinear (black dots) and tone-responsive (gray dots) units. Nonlinear units were located at shallower cortical depths compared with tone-responsive units (histograms of absolute and relative depths are on margins, numbers are medians; *p < 0.05, **p < 0.01, Wilcoxon rank-sum test). This suggested that nonlinear neurons may be localized to superficial cortical layers. B, Distribution of all observed subunits plotted relative to normalized BF. Gray ellipses are locations of statistically significant nonlinear subunits; shading corresponds to the percentage of facilitation. Most subunits were located <0.5 octaves away from BF suggesting a local computation. Most subunits also occurred within 50 ms of the BF pip.