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. 2018 Jan 23;7:e30649. doi: 10.7554/eLife.30649

Figure 2. Overexpression of FoxP2 isoforms affect song learning and/or song variability.

(A) Timeline of experimental procedures relative to critical periods in song development. (B) Schematic illustrates NS-UD or UD-UD experiments performed on adjacent days. (C) The effect size of two hours of UD singing on syllable CV was calculated using the formula (NS-UD)/(NS + UD) after an NS-UD, UD-UD experiment performed at ~60d and 61d as in (B). Overexpression of FoxP2.FL (grey bars; n = 16 syllables; Duration = −0.059 ± 0.029; AM = −0.010 ± 0.028; Entropy = −0.038 ± 0.04) diminishes singing induced variability relative to that seen in GFP-expressing controls (green bars; n = 9 syllables; Duration = −0.128 ± 0.071; AM = −0.065 ± 0.035; Entropy = −0.091 ± 0.034). In contrast, overexpression of FoxP2.10+ (red bars; n = 13 syllables; Duration = 0.070 ± 0.054; AM = 0.088 ± 0.047; Entropy = 0.048 ± 0.029) leads to a singing-induced state of relative invariability. Values and bar heights represent the average effect size for all syllables within the virus construct group ±SEM. * denotes significant result in one-way ANOVA (Duration: F(2,35) = 3.95, p=0.028; AM: F(2,35) = 3.96, p=0.028; Entropy: F(2,35) = 3.63, p=0.037) and Tukey’s HSD post-hoc test (p<0.05). (D) Learning curves plot the relationship between percentage similarity to tutor as a function of time. Animals overexpressing GFP (green; letter ‘B’; n = 7 birds;~65 d similarity = 67.2 ± 6.64%) or FoxP2.10+ (red, letter ‘A’; n = 5 birds;~65 d similarity = 75.8 ± 2%) learn significantly better than those overexpressing FoxP2.FL (grey, letter ‘C’; n = 5 birds;~65 d similarity = 44.3 ± 10.1%). Values are mean ±SEM. Data are binned by day (top panel; bold points represent group mean and shifted smaller points are individual birds) or by individuals (bottom panel). Significantly different groups tested by one-way ANOVA (Bin 1:~40d F(2,11) = 6.06, p=0.016; Bin 3:~55d F(2,13) = 6.04, p=0.014; Bin 4:~60d F(2,14) = 9.94, p=0.002; Bin 5:~65d F(2,14) = 4.76, p=0.026) and Tukey HSD post-hoc test (p<0.05) are denoted by capital and lowercase lettering. (E) Exemplar motifs of a tutor and three of his 65d pupils, each of which was injected with a different viral construct at 30d. These examples illustrate the percent similarity depicted in panel D. (F) Summary of the learning and variability phenotypes observed after virus injection.

Figure 2—source data 1. Contains the effect sizes for each syllable that are presented in (C).
elife-30649-fig2-data1.xlsx (50.1KB, xlsx)
DOI: 10.7554/eLife.30649.010
Figure 2—source data 2. Contains the binned similarity scores presented in the upper plot in (D).
elife-30649-fig2-data2.xlsx (41KB, xlsx)
DOI: 10.7554/eLife.30649.011

Figure 2.

Figure 2—figure supplement 1. Raw acoustic feature variability in the NS-UD and UD-UD conditions by virus group.

Figure 2—figure supplement 1.

The raw acoustic feature CVs transformed by the calculation in Figure 2C show the variability relationship between NS-UD and UD-UD paradigms for all measured acoustic features. For most song features, UD singing drives increases in CV in the GFP group. This effect is blocked or reversed in the FoxP2.FL and FoxP2.10+ groups, respectively. Notably, the songs of FoxP2.10+ animals following 2 hr of UD song were significantly less variable than those after 2 hr of non-singing. Asterisks indicate a significant difference (p<0.05) in a paired resampling test within virus construct. See Materials and methods for more information regarding the transformation of raw data to effect size.