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 Penn investigated how a zebra finch learns songs from a different perspective: 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 in the journal eLife.

The research was led by Vijay Balasubramanian, a physics professor in the School of Arts & Sciences, and Tiberiu Teșileanu, a visiting scholar.

The bird’s learning process can be thought of 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 says.

The key to this learning is that synapses in the brain strengthen or weaken based on a bird’s experiences of the world. Much of the focus in the field has been on learning rules, how these synapses change strength.

But often, says Balasubramanian, one bit of the brain has to teach another bit of the brain how to do something. When the student part of the brain is learning how to sing a song, the tutor part has to tell it whether the song it produced was good or bad, and give instructions on how to improve. The researchers decided to focus on these teaching rules.

There are many different learning styles the student playing the violin might have. Some people are auditory learners; others are visual learners. Depending on the style of learning, different kinds of teaching may be more or less effective. The researchers found that the same is true in the brains of songbirds. Based on the synaptic plasticity rules, which are the learning rules used by neurons, different types of teaching rules in the brain will be more effective.

The researchers hope to think about this idea of matched learning and teaching in mammalian brains and cortical networks, which allow learning of motor function. Learning, Balasubramanian says, doesn’t just involve the student. It also involves the teacher. It’s important to understand the roles of both of these areas of the brain.

“Over eons, structures in the brain have adapted to each other to produce function,” he says. “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.”