Extended Data Fig. 10: Pitch encoding in budgerigar AAC.

a, Schematic of pitch tuning index calculation. b, Pitch tuning in three example neurons from Fig. 4g, presented as binned scatter plots (gray) and averaged firing rates (mean ± SEM) across pitches (green) for all vocal elements (left), only calls (middle), and only warble syllables (right). Blue circles represent baseline firing rates. c, Relative contributions of four acoustic features in GLM models explaining single AAC neuron responses shown for all neurons (left), pitch-tuned neurons (pitch tuning index > 6; middle), and non-tuned neurons (pitch tuning index <6; right), respectively. Boxplot elements: center line, median; box limits, upper and lower quartiles; whiskers, minimum and maximum values excluding outliers. Exact p-values shown within each plot are from Bonferroni-corrected, two-sided Wilcoxon signed-rank tests (n = 220, 112, 108 neurons for each plot, respectively). d, Relationship between decoded and measured pitches across all calls for each budgerigar, shown as binned scatter plots. Linear decoders trained on warble syllables were used to predict pitch in calls. R values represent Pearson correlation between decoded and measured pitches.