A good teacher is essential in learning to communicate. Take, for example, the zebra finch. Juveniles of the species learn songs directly from a teacher – usually their father – through a social interaction that keeps them motivated and on task. Young birds that listen to songs through a speaker without face-to-face instruction from a teacher do not learn them nearly as well.
How exactly this social component of song learning works has long been a mystery. But now, researchers at the Okinawa Institute of Science and Technology (OIST) have identified the brain’s circuit that controls it. they reported their findings nature communication,
“This study is the first demonstration of the neural circuitry that is telling these animals what incoming information they need to pay attention to,” says Yoko Yazaki-Sugiyama, associate professor at OIST’s Neural Mechanisms for Critical Period Unit, who research led.
In the wild, zebra finches are surrounded by a variety of sounds, including the songs of other types of birds, says Dr. Yazaki-Sugiyama. “This circuit is activated to indicate that the song, coming from the tutor, is important and needs to be remembered,” she says.
About 20 years ago, scientists studying human babies noticed that they, too, needed a personal guide to learn to recognize vowels in language. Those scientists hypothesized that social interaction attracted learners’ attention.
It is quite logical – if we are attentive, we are learning better. We wanted to understand, is the same true for juvenile birds?”
Dr. Jelena Katic, postdoc in the Nervous System for the Critical Period Unit and first author of the study
The researchers focused on a brain region called the locus coeruleus (LC), which is known to be involved in attention and arousal. Neurons from this brain region project into a higher order auditory area in the brain called the caudomedial nidopallium (NCM). Previous work in his lab suggested that this is where a juvenile’s memories of a teacher’s song are formed in the zebra finches.
“We hypothesized that this LC-NCM circuit may be important, but no one had ever observed it in adolescents,” says Dr. Katic.
Over a few days, the researchers recorded brain activity in these two areas under different conditions: first, while teens, who had never heard a teacher’s song before, listened to it through a speaker; Thereafter, when Kishore interacted with the tutor, he sang to him; And finally, once again listening to the tutor’s song through the speaker.
Both brain regions responded more strongly when the tutor sang than when the youth listened to the recording beforehand. Interestingly, listening to the tutor’s vocals also increased the teen’s response to the later recording. The firing of NCM neurons was time-locked to specific syllables of the tutor’s song, suggesting that these neurons were recording auditory information. But the LC neurons were continuously active while the tutor sang, suggesting that they were responding to vocal communication more than the specific notes they emitted.
And if the researchers disabled the neurons projecting from the LC to the NCM when the tutor sang along with social interaction, the teens were unable to accurately copy their song.
“Imagine NCM neurons receiving multiple inputs from different regions of the brain, including some from auditory regions that convey song notes and prosodytic patterns,” Katic says. “But LC is conveying another type of information – the social context recognizing that the song is important,” Dr. Katic says.
Researchers do not yet know what cues adolescents use to capture this social context. But they speculate that this circuit may be particularly important in development, when an adolescent is forming memories of songs. “If memories are poorly formed, the bird is not going to be able to vocally copy them later,” she says.
Scientists are investigating how this social learning circuit functions – for example, what chemicals it uses and what kinds of information LC neurons capture in order to measure the importance of what the zebra finch hears. . They are also exploring what kinds of cues teens leave that might encourage a tutor to teach them. Pro. “This exchange between the teen and the teacher takes place in two directions,” says Yazaki-Sugiyama.
Okinawa Institute of Science and Technology (OIST) Graduate University
Katic, J., and others. (2022) Neural circuits for social authentication in song learning. nature communication. doi.org/10.1038/s41467-022-32207-1.