Top row (A, B, C): results from imaging experiments using GCaMP6m as calcium indicator. Bottom row (D, E, F): same analyses as in A, B, C above, but using data from GCaMP6f experiments. (A, D) Cumulative probability plots of the difference (in octaves) between each neuron’s BF and the median BF of all neurons of the same FRA class in the same imaging field. Distributions for different FRA classes are plotted separately as colored lines, as in Figure 2C (see legend in A). (B, E) Magnitude of the trial-averaged response at BF and best level, calculated from deconvolved fluorescence traces. Responses were averaged across all neurons in each FRA class, and pooled across imaging fields and ferrets (mean ± SEM). (C, F) Fano Factor values (mean ± SEM) for single-peaked, double-peaked, and complex neurons. The results of t-tests are indicated above the bars in (B, E) (*p < 0.05, **p < 0.01 and *** p < 0.001).