Fig. 6

FoxP2 expression and individual variation in vocal learning. Scatterplots of the relationship between vocal learning measures and FoxP2 protein expression ratio (MMSt/VSP), fit linearly for each adult age class. FoxP2 expression ratios below 1 indicate lower FoxP2 expression in the vocal learning striatal nucleus, MMSt, relative to the adjacent striatum, VSP. (a) Change in the area of an individual’s acoustic space from the beginning of the vocal learning assay (audio-recording block 1) to the end (audio-recording block 5), where 0 indicates no change in vocal diversity, positive values indicate an increase in vocal diversity, and negative values indicate a decrease in vocal diversity. (b) 1 minus the intersection over union of an individual’s beginning and ending acoustic spaces, where higher values on the y-axis indicate greater vocal plasticity. (c) Intersection over union of an individual’s acoustic space and the combined acoustic space of its flockmates, where higher values indicate greater vocal convergence