Singing mice show signs of learning
"We are claiming that mice have limited versions of the brain and behavior traits for vocal learning that are found in humans for learning speech and in birds for learning song," said Duke neurobiologist Erich Jarvis, who oversaw the study. The results appear Oct. 10 in PLOS ONE and are further described in a review article in Brain and Language.
The discovery contradicts scientists' 60-year-old assumption that mice do not have vocal learning traits at all. "If we're not wrong, these findings will be a big boost to scientists studying diseases like autism and anxiety disorders," said Jarvis, who is a Howard Hughes Medical Institute investigator. "The researchers who use mouse models of the vocal communication effects of these diseases will finally know the brain system that controls the mice's vocalizations."
Jarvis acknowledged that the findings are controversial because they contradict scientists' long-held assumption about mice vocalizations. His research suggests the vocal communication pathways in mice brains are more similar to those in human brains than to sound-making circuits in the brains of chimpanzees and other non-human primates. The results also contradict two recent studies suggesting mice do not match pitch or have deafness-induced vocalization changes.
Singing Mice Show Signs of Learning | Duke Today
Male mice may learn to match other males' ultrasonic squeaks to get the girls. Credit: iStock.
In the study, funded by HHMI, NSF and NIH, Arriaga first used gene expression markers, which lit up neurons in the motor cortex of the mice's brain as they sang. Arriaga then damaged these song-specific neurons in the motor cortex and observed that the mice couldn’t keep their songs on pitch or repeat them as consistently, which also happened when the mice became deaf.
This image shows the motor cortex neurons that directly project to the brainstem and ultimately control the larynx of male mice. Credit: Gustavo Arriaga and Erich Jarvis, Duke.
PLOS ONE: Of Mice, Birds, and Men: The Mouse Ultrasonic Song System Has Some Features Similar to Humans and Song-Learning Birds
Figure 1. Brain systems for vocalization in birds and mammals.
A, Typical ultrasonic song segment (sonogram) of a male B6D2F1/J (BxD) mouse produced in response to presentation of female urine. Multiple distinct syllables (letters) are produced in long sequences (sometimes over 30 sec), but only 1 second is shown so that the frequency contours and nonlinearities of individual units can be resolved. The sonogram was generated from Audio S1.
Audio S1.
Example of a normal adult BxD mouse song (audio corresponds to sonogram of USVs in Figure 1A ).
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Duke Institute for Brain Sciences - Jarvis, Erich - Ph.D. | Duke Institute for Brain Sciences | Brain Research
Erich Jarvis, Ph.D.
Associate Professor; Howard Hughes Medical Institute InvestigatorNeurobiology, School of MedicineDIBS FacultyResearch Description
Our goal is to understanding the molecular mechanisms that construct, modify, and maintain neural circuits for vocal learning. Vocal learning is the ability to modify or imitate the acoustic structure and sequence of vocalizations and is a critical behavioral substrate for spoken language. Studying these mechanisms requires that we compare the genes, vocal behavior, and associated brain pathways of the few rare groups that have vocal learning with the vast majority of species that do not. [...]
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