Fig. 5.

Nonobvious change in song structure by ablation of HVC_(X) neurons in adults. (A) Representative spectrogram of birds that were ablated in HVC_(X) neurons in adults. The white bars represent the motif structure of songs. (B) Example of the extent of HVC_(X) ablation in an ablated adult (with 76.9% ablation) as shown in A and C. NTS (red) and DAPI (blue). (C) Syllable sequence and acoustic stability before and after ablation of HVC_(X) neurons. Sequential patterns are shown as SSMs and acoustics as a scatter density plot of syllable duration vs. mean FM (n = 150 syllables). (D) No effect of HVC_(X) ablation on the song motif index of adult zebra finches. Each point corresponds to an individual bird. (E) No effect of HVC_(X) ablation on syllable acoustics measured by the K–L distance of syllable scatter density plots (duration vs. mean FM) between preinjection and postinjection time points (n = 3 controls, n = 4 ablated birds; Student’s t test: n.s., P > 0.05). (F) Pre–post change in motif duration between control and HVC_(X)-ablated birds (Student’s t test: n.s., P > 0.05). (G) Example of an FF trajectory of a syllable in preinjection (Top Left) and 2 wk postinjection (Top Right) of songs from an HVC_(X)-ablated adult, expressed as raw frequency traces (Middle) and percent deviation from the within-rendition mean (Bottom). The blue and red lines indicate each rendition and the mean across renditions, respectively. (H) Pre–post changes in within- and cross-rendition syllable variability in FF between control and HVC_(X)-ablated birds (Student’s t test: n.s., P > 0.05). Mean + SEM for all graphs.