May 2, 2008
Baby birds, much like their human counterparts, babble first as they learn to mimic adult birdsong, a new study says which could help explain how humans gain new skills.
"The babbling during song learning exemplifies the ubiquitous exploratory behavior that we often call play but that is essential for trial-and-error learning," said neuroscientist Michale Fee, lead author of the study by the Massachusetts Institute of Technology.
Baby zebra finches warble away with a highly variable song, and practice non-stop until they get it right and can copy the never-ending calls of their parents, the study said.
"This early variability is necessary for learning, so we wanted to determine whether it is produced by an immature adult motor pathway or by some other circuit," Fee said in the study published Thursday in Science.
Past studies on the zebra finch revealed that the tiny songbirds have two separate brain circuits dedicated to song, one for learning and another, called the motor circuit, for actually producing the learned song.
If the first circuit is damaged in any way while the youngster is still in training then it will be unable to learn more and its call will not fully develop.
But if an adult zebra finch, which has already learned to sing, loses capacity of this part of its brain, that will not affect its singing abilities.
The MIT team decided to study what happens if the motor circuit is disabled in baby birds, and surprisingly found that they continued to sing, meaning some other part of the brain produces the babbling.
"This tells us that singing is driven by two different motor circuits at different stages of development," said author Dmitriy Aronov.
Researchers also found that in adult birds, the learning circuit does not atrophy out of lack of use, but rather remains intact and if the motor circuit is disrupted the adults will immediately begin babbling again.
The research could have implications in understanding how humans learn new behavior, Fee said.
"In birds, the exploratory phase ends when learning is complete," he said. "But we humans can always call upon our equivalent of (the learning circuit), the prefrontal cortex, to be innovative and learn new things."