How practice improves zebra finch’s singing performance

July 7th, 2009 - 5:36 pm ICT by ANI  

Washington, July 7 (ANI): A study on zebra finches conducted by neuroscientists at the Massachusetts Institute of Technology (MIT) has shed some light on how practice improves performance.

The researchers say that studying the chirps of zebra finches helped them determine that as these tiny songbirds fine-tune their songs, their brains initially store improvements in one brain pathway, before transferring this learned information to the motor pathway for long-term storage.

They believe that their findings may further scientists’ understanding of the complicated circuitry of the basal ganglia, brain structures that play a key role in learning and habit formation in humans.

The basal ganglia are also linked to disorders like Parkinson’s disease, obsessive-compulsive disorder and drug addiction.

“Birds provide a great system to study the fundamental mechanisms of how the basal ganglia contributes to learning. Our results support the idea that the basal ganglia are the gateway through which newly acquired information affects our actions,” said senior author Michale Fee, an investigator in the McGovern Institute for Brain Research at MIT.

The researchers point out that young zebra finches learn to sing by mimicking their fathers, whose song contains multiple syllables in a particular sequence.

Like the babbling of human babies, young birds initially produce a disorganized stream of tones, but after practicing thousands of times they master the syllables and rhythms of their father’s song.

Studies conducted in the past have identified two distinct brain circuits that contribute to this behaviour in zebra flinches.

A motor pathway is responsible for producing the song, and a separate pathway is essential for learning to imitate the father. The learning pathway, called the anterior forebrain pathway (AFP), has similarities to basal ganglia circuits in humans.

“For this study, we wanted to know how these two pathways work together as the bird is learning. So we trained the birds to learn a new variation in their song and then we inactivated the AFP circuit to see how it was contributing to the learning,” said first author Aaron Andalman, a graduate student in Fee’s lab.

With a view to training the birds, the research team monitored their singing and delivered white noise whenever a bird sang a particular syllable at a lower pitch than usual.

“The bird hears this unexpected noise, thinks it made a ‘mistake’, and on future attempts gradually adjusts the pitch of that syllable upward to avoid repeating that error. Over many days we can train the bird to move the pitch of the syllable up and down the musical scale,” Fee said.

On a particular day, after four hours of training in which the birds learned to raise the pitch, the researchers temporarily inactivated the AFP with a drug. The pitch immediately slipped back to where it had been at the start of that day’s training session - suggesting that the recently learned changes were stored within the AFP.

The research group, however, observed that over the course of 24 hours, the brain had transferred the newly learned information from the AFP to the motor pathway. The motor pathway was storing all of the accumulated pitch changes from previous training sessions. (ANI)

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