Their songs have less structure each morning and regain their complexity each afternoon. This daily pattern of variation is important for song learningbirds that have the greatest variation early in development are the ones that ultimately learn the best.
"We now have a new model for how this works," said Margoliash. "At night, the auditory information that the bird was exposed to during the day is reactivated, [carried by the spontaneous activity of neurons], changing the structure of the neural networks. These changes interact with changes during the day as birds listen to tutor songs and practice singing." The authors suggest that reactivation of sensory information at night might be a general mechanism for learning a new skill.
In previous work, Margoliash and his team identified places in the brain where nighttime activity is reactivated. In adult birds, individual cells spontaneously emitted patterns of bursts during sleep that were very similar to the burst patterns emitted when the bird sang during the day.
In the current study, the University team was able, for the first time, to look at juvenile zebra finches. Using microelectrodes, the team observed changes in neuronal activity during sleep in a region of the young zebra finch brain involved in singingthe acropalium (RA).
Shank and Margoliash first looked at the effects of exposing birds to different tutor songs. They then extended that work to the role of auditory feedback in driving learning. They wanted to see whether changes in the brain brought on during sleep after exposure to a new song were reinforced by practice as well as daytime listening. They theorized that
|Contact: William Harms|
University of Chicago