Figure 4
Representative sonograms of songs and mean end syllable repetitions before (presurgery) and after (postsurgery) injections. (a) Presurgery song of a control bird Pink 124. (b) Postsurgery song of Pink 124 injected with eGFPhNR2B lentivirus in the motor nidopallium showing no change in song after injections. (c) Presurgery song motif of a bird Green 04. (d) Postsurgery song motif of Green 04 showing end motif syllable stuttering after overexpression of human NR2B in LMAN. Black letters indicate syllable types in song motifs. Sonograms were generated using Avisoft-SASLab Pro software (Avisoft Bioacoustics, Germany). (e) Mean number of end syllable repetitions in control and NR2B groups of birds. (f) Time course of mean end syllable stuttering in birds (n = 8) of the NR2B overexpression group that were injected with the eGFPhNR2B lentivirus in LMAN. Pre indicates end syllable repetitions before injections. Each time point is an average of 10 song bouts; weeks 2–12 were compared to presurgery levels using paired t tests; asterisk represents p value < 0.01. (g) Percentage of motifs (mean ± SE) showing end syllable and introductory note repetitions in birds of the controls and NR2B groups. We used a cut-off of more than 3 repeats of introductory notes at the beginning of each motif of a song bout to be included as repetitions in our analyses for quantification. P values were determined using paired Wilcoxon signed-rank tests.
