Parrots and songbirds have evolved distinct brain mechanisms, study finds

When humans learn to speak a language, we learn to produce new vocalizations and use them flexibly to communicate, but how the brain achieves this is an important but largely unanswered question, according to Zhilei Zhao, Klarman Fellow in Neurobiology and Behavior in the College of Arts and Sciences (A&S).

To explore this question, Zhao and Cornell’s collaborators compared the brain pathways of songbirds and parrots. The two groups diverged 50 million years ago but both have the capacity for vocal learning. The researchers discovered radically different effects in the brain mechanisms of the two species, providing insight into how the brains of parrots and humans enable continuous and flexible vocal learning.

“The anterior forebrain pathway in parrots is required to produce vocalization with individual signatures” is published in Current biology on December 8 with Zhao as first author.

Songbirds and parrots are a useful comparison because they have distinct evolutionary histories and vocal learning abilities, Zhao said.

Zebra finches, the most studied songbird species, learn a song in the juvenile stage and have little change afterward. This is very different from parrots and humans, who continually learn new vocalizations throughout their lives and produce flexible vocal sequences.

Both songbirds and parrots have two main pathways in the brain: anterior and posterior. In songbirds, these two pathways are known to serve different functions. But the functions they play in parrots remain unknown.

To test whether parrot song systems have similar neural function to songbirds, the researchers temporarily and reversibly inactivated each of the parrots’ neural pathways and found very different effects in parrots and songbirds. .

Songbirds can continue to produce their vocalizations using only the posterior pathway, but in parrots, isolation of this pathway has led to a complete destruction of vocal ability. The experiment showed that parrots need the anterior forebrain pathway to produce learned vocalizations with individual signatures.

These findings suggest that their functions have diverged significantly, even though anatomically they look similar, Zhao said: “In short, to continually learn and vocalize flexibly as humans do, parrots have evolved brain mechanisms distinct from those songbirds.”