Parrots, which are close to humans in learning vocals and imitate sounds than any other species, a new study has found that parrot’s tiny brain is structured differently than the brains of songbirds and hummingbirds, which also exhibit vocal learning.
Mukta Chakraborty, a postdoc in the Jarvis lab, led a project that used the activity of some of the specialized genes to discover that the parrot’s speech center is organized somewhat differently. It has what the researchers call a “song-system-within-a-song-system” in which the area of the brain with different gene activity for producing song has an outer ring of still more differences in gene expression.
Parrots are very social animals, Chakraborty said, and having the ability to quickly pick up “dialects” of parrot speech may account for their super-charged speech center. The ”shell” or outer regions were found to be proportionally larger in the parrot species, which are believed to have the highest vocal, cognitive and social abilities. These species include Amazon parrots, the African Grey and the Blue and Gold Macaw.
Until now, the budgerigar (common pet parakeet) was the only species of parrot whose brain had been probed for the mechanisms of vocal learning.
Published in PLOS ONE, the research paper says brain structures in parrot had gone unrecognized in studies published over the last 34 years and stressed the need to lend insight into the neural mechanisms of human speech.
Mukta Chakraborty said: “This finding opens up a huge avenue of research in parrots, in trying to understand how parrots are processing the information necessary to copy novel sounds and what are the mechanisms that underlie imitation of human speech sounds.”
This team characterized the brains of eight parrot species besides the budgerigar, including conures, cockatiels, lovebirds, two species of Amazon parrots, a blue and gold macaw, a kea and an African Grey parrot. They tried to identify geme expression patterns in all barrot brains with neural tracing experiments in budgerigars.
“It takes significant brain power to process auditory information and produce the movements necessary for mimicking sounds of another species,” Chakraborty said. “The question is, how specialized are these parrot brains, and in what ways? Is it just a select group of specialized genes, or is it some specific projections that we haven’t discovered yet?”
The scientists are especially curious about whether the shells give parrots a greater ability to imitate human speech.”If that’s true, then we’ve answered a big question in our field that people have been wanting to know for many years,” Jarvis said.
This finding is a part of a global project to sequence the complete genomes of all 10,000 species of birds in the next five years, called the Bird 10K Project.
After comparing the entire genomes of 48 species of birds representing every major order of the bird family tree, Jarvis and his colleagues found that vocal learning evolved twice or maybe three times among songbirds, parrots and hummingbirds.
Even more striking is that the set of genes involved in each of those song innovations is remarkably similar to the genes involved in human speaking ability.
Another paper in Science from Duke, led by post-doc Osceola Whitney, Pfenning, Hartemink and Anne West, looked at gene activation in different areas of the brain during singing. This team found activation of 10 percent of the expressed genome during singing, with diverse activation patterns in different song-learning regions of the brain.