Supplementary Figure 8: Neural discrimination of songs varied between song types, pupil groups, and AC regions in parallel with differences in spike rate.
From: Emergent tuning for learned vocalizations in auditory cortex
An unbounded neural discrimination metric (d-prime) was computed to measure how accurately single-trial spike trains distinguished among songs of the same species (n = 5 ZF, LF, and BF songs; 10 trials per stimulus). Plots show a difference in d-prime between song types to be consistent with plots of song selectivity. a, In zfZF birds, single neurons in the intermediate, superficial, deep, and secondary regions (n = 113, 111, 186, 140 neurons, respectively) tended to discriminate among ZF songs better than among LF songs. Intermediate-region neurons in lfLF birds also discriminated among ZF songs better than LF songs, but secondary-region neurons performed better to LF songs (n = 98, 33, 123, 37 neurons across AC regions). The difference between groups was significant in the deep region. b, Same as a, but comparing discrimination of ZF versus BF songs in zfZF birds (n = 126, 117, 202, 127 neurons) and zfBF birds (n = 38, 49, 91, 159 neurons). Deep- and secondary-region neurons in zfZF birds discriminated among ZF songs better than BF songs, but there was no difference between song types in zfBF birds. The difference between groups was significant for the deep region. c, Same as a, but comparing discrimination of LF versus BF songs in lfLF birds (n = 135, 40, 153, 120 neurons) and lfBF birds (n = 95, 15, 42, 122 neurons). In lfLF birds, intermediate-region neurons discriminated among BF songs better than LF songs, but secondary-region neurons did better among LF songs. In contrast, intermediate-, deep-, and secondary-region neurons in lfBF birds all discriminated among BF songs better than among LF songs. The difference between groups was signifcant for the deep region. For a-c, the measure of center is the median, box limits show the 25th and 75th percentiles, whiskers extend up to 1.5× the interquartile range beyond the quartiles; and circles show outliers. Colored stars indicate a difference in discrimination between song types within a group (repeated-measures ANOVAs with bird identity as a covariate). Black stars indicate a difference between bird groups (ANOVAs with bird identity as a nested covariate). *P < 0.05, **P < 0.01, ***P < 0.001. d, Correlations between spike rate selectivity and the difference in neural discrimination between song types in zfZF birds (0.25 ≤ all partial r ≤ 0.62, all P < 0.01 across AC regions) and lfLF birds (intermediate, deep, secondary: 0.43 ≤ r ≤ 0.68, P < 0.01). e, Same as d, but showing correlations zfZF birds (0.23 ≤ all partial r ≤ 0.50, all P < 0.02) and zfBF birds (superficial, deep, secondary: 0.45 ≤ r ≤ 0.54, P < 0.001). f, Same as d, but showing correlations in lfLF birds (0.50 ≤ all partial r ≤ 0.63, all P < 0.001) and lfBF birds (intermediate, deep, secondary: 0.33 ≤ r ≤ 0.61, P < 0.05). For d-f, regressions included bird identity as a covariate. Sample sizes are the same as in a-c.
