A new study at University of Pennsylvania took a different look at the way songbirds learn to sing. The study, “Rules and mechanisms for efficient two-stage learning in neural circuits,” in the journal eLife, focused on the way one part of a zebra finch’s brain teaches another part of the brain and adapts its teaching style to the way the brain learns.

The song learning process for zebra finches is similar to that of a musician learning to play a piece on an instrument: the bird hears the song, remembers it, sings it back and continues to adjust its performance of the song until it sounds right. While singing, the bird learns to control its vocal organ, the syrinx, and its respiratory muscles.

“They start out babbling, and then eventually this congeals into trills and phrases and sounds like a song,” said Vijay Balasubramanian, a physics professor in Penn’s School of Arts & Sciences and a lead researcher of the study.

The researchers labeled the two parts of the brain the “tutor” and the “student.” They found that the tutor part of the brain tells the student part of the brain whether the song it produced was good or bad and instructs it on how to improve. Based on the synaptic plasticity rules—the learning rules used by neurons—different types of teaching can be more or less effective.

“Depending on how the neuron changes its strength of connections,” Dr. Balasubramanian said, “the teaching signal coming from another place should be adapted to the area of the brain that’s trying to learn, in such a manner as to help it learn well. In this paper, we worked out good teaching rules, or how the teacher should adapt to the student to teach it well, and used them to try to make some predictions about how learning would work in the song-learning system of the bird.”

The researchers used data compiled by Bence Ölveczky, a professor of organismic and evolutionary biology at Harvard University, from recordings of neurons in different areas of the birds’ brains to create a mathematical framework. They hope their findings can be applied to mammalian brains and cortical networks, which allow learning of motor function.

“Over eons, structures in the brain have adapted to each other to produce function,” Dr. Balasubramanian said. “I suspect it’s just the case that brain areas are adapted to send messages to each other in ways that make themselves work well. I think it’s a new handle or lever for investigation to think about that: How a tutor area of the brain should structure its signals so that a student area can profit from the signal as best as possible given its constraints and its learning rule.”