Researchers create ‘wiring diagram’ for key songbird brain region
UTSW study aims to better understand how human speech develops or goes awry in communication disorders
DALLAS – April 10, 2025 – Much like human beings, songbirds learn how to vocalize from their parents. Males imitate songs from their fathers and then sing to attract mates. Although the circuits that generate human speech are more complicated to decipher, the brains of songbirds offer a viable model for better understanding how humans learn to speak and what goes wrong in communication disorders such as autism.
Todd Roberts, Ph.D., Associate Professor of Neuroscience and an Investigator in the Peter O’Donnell Jr. Brain Institute at UT Southwestern, has devoted his career to the study of songbirds. His latest study, published in eLife, reports the first “wiring diagram” of interconnected circuits in a critical region of the songbird brain, providing important insights into how vocal learning occurs in songbirds that could help researchers develop better models of human speech.
“Learned vocalizations are controlled by a complex of interconnected sensory and motor circuits in the brain, but the details of how these different sensory and motor pathways ‘talk’ to each other has been difficult to ascertain using standard approaches,” said Dr. Roberts, who co-led the study with Massimo Trusel, Ph.D., Instructor of Neuroscience. “This research breaks new ground by providing the first cell-type specific functional mapping of connectivity within core sensory and motor pathways critical for vocal learning.”
Drs. Roberts and Trusel and their colleagues worked with zebra finches, songbirds often kept as pets in the U.S. and the most-studied model species for vocal learning. For decades, researchers have known that an area of the avian brain named “HVC” is critical for birdsong. Damaging this area substantially impairs songbirds’ ability to sing, and removing it blocks song generation. Earlier anatomical studies have shown that the HVC acts like a hub, receiving electrical inputs from four brain regions and sending electrical outputs to three other brain regions. But how these input and output circuits are wired to transfer information through this hub has been unclear.
To shed light on this process, the UTSW researchers used a technique called optogenetic circuit mapping, in which they inserted a gene into targeted neurons, allowing their activity to be controlled by light. By stimulating individual groups of neurons delivering inputs to the HVC and then measuring the electrical activity of outputting neurons, they could see which neurons communicated with one another.
Their findings revealed an unexpectedly high degree of specificity in how input circuits wire with output circuits to transfer information through this hub. Their connectivity mapping of one input pathway, a brain region called the nucleus interfacialis, showed that it communicates with all three groups of output neurons in the HVC. Another input pathway, from a brain region called the nucleus uvaeformis, communicates with just one output pathway in the HVC. A mirror image of such connectivity is displayed by a third input, from a region called the medial magnocellular nucleus, which communicates strongly with the two output pathways neglected by the nucleus uvaeformis. A fourth input pathway, from a region called the nucleus avalanche, communicates strongly with one output pathway and more sparsely with the other two.
Surprisingly, the researchers also found that two of these input pathways directly communicate with each other, revealing a previously unknown connection within this well-studied circuit. The researchers plan to investigate this newfound connection in a future study. They also plan to study how perturbing individual parts of this system affects singing behavior in zebra finches and use this detailed circuit map to build computational models for how these brain regions function in learning and producing vocalizations.
Other UTSW researchers who contributed to this study include Ziran Zhao, B.S., graduate student researcher; Ethan Marks, B.S., Research Technician; and Danyal Alam, Ph.D., a former graduate student in the Roberts Lab.
Dr. Roberts is a Thomas O. Hicks Scholar in Medical Research at UTSW.
This research was supported by grants from the National Institutes of Health (UF1NS115821 and R01NS108424).
About UT Southwestern Medical Center
UT Southwestern, one of the nation’s premier academic medical centers, integrates pioneering biomedical research with exceptional clinical care and education. The institution’s faculty members have received six Nobel Prizes and include 25 members of the National Academy of Sciences, 23 members of the National Academy of Medicine, and 14 Howard Hughes Medical Institute Investigators. The full-time faculty of more than 3,200 is responsible for groundbreaking medical advances and is committed to translating science-driven research quickly to new clinical treatments. UT Southwestern physicians provide care in more than 80 specialties to more than 120,000 hospitalized patients, more than 360,000 emergency room cases, and oversee nearly 5 million outpatient visits a year.