Figure 7.

LAT and MED HVC ablations affect singing differently. A, B, Example spectrograms show that birds omit syllables at POST when LAT HVC is bilaterally damaged, resulting in incomplete motifs. Syllable transition diagrams accompanying each spectrogram show the changes in syllable transition types associated with this deficit. Grayscale represents the relative probabilities of transitions between pairs of motif syllables. At PRE, different proportions of the transitions throughout a day of singing correspond to transitions between pairs of motif syllables. At POST, all transitions now occur between syllables A and B because only those two syllables were sung by these two birds. The omission of motif syllables at POST was characteristic of birds with LAT HVC ablations and was wholesale in 3 of 5 birds in this group. C, D, Example spectrograms and syllable transition diagrams show that birds with bilateral MED HVC damage sing all of their motif syllables at POST, but they intermittently produce their motif syllables out of the canonical order observed at PRE. New and atypical transition types are present at POST (e.g., B-A and A-G at POST in C). Atypical syllable transitions were characteristic of birds with MED HVC ablations, although this deficit was never wholesale: all birds in this group retained the ability to intermittently produce their canonical PRE motif.