Date: April 4, 2017
Source: University of Pennsylvania
Music can be a powerful form of expression. It's especially important for songbirds such as zebra finches, which learn the songs of their fathers in order to court mates.
Until now, scientists have typically thought of the bird's vocal development in terms of how one circuit in the brain learns a song. But a new study by researchers at the University of Pennsylvania investigated how zebra finches learn songs from a different perspective. Instead of looking at how the bird's brain learns a song, they studied how one part of its brain, which they dubbed the "tutor," teaches another part of its brain, the "student."
The researchers found that in order to teach effectively, the tutor must adapt its teaching style to how the student best learns. The study, titled "Rules and mechanisms for efficient two-stage learning in neural circuits," appeared today in the journal eLife.
The research was led by Vijay Balasubramanian, a physics professor in Penn's School of Arts & Sciences, and Tiberiu Tesileanu, a visiting scholar whose main appointment is at the City University of New York Graduate Center. Bence Ölveczky, a professor of organismic and evolutionary biology at Harvard University, also contributed to the study.
One can think of the bird's learning process as a musician learning a piece on the violin: After practicing the song over and over again until it sounds right, playing it becomes second nature to the violinist.
In the case of zebra finches, the bird hears the song, remembers it, sings it back and continues to adjust it over a period of about a month until it sounds right. As the bird sings, it learns to control its syrinx, the animal's vocal organ, and its respiratory muscles.
"They start out babbling, and then eventually this congeals into trills and phrases and sounds like a song," Balasubramanian said.
The key to this learning is that synapses in the brain strengthen or weaken based on one's experiences of the world. Much of the focus in the field has been on learning rules, how these synapses change strength. An example of this is the Hebb rule, which says that two neurons firing coincidentally at the same time will strengthen their synapse.