Of mice, birds, and men: the mouse ultrasonic song system has some features similar to humans and song-learning birds.

Humans and song-learning birds communicate acoustically using learned vocalizations. The characteristic features of this social communication behavior include vocal control by forebrain motor areas, a direct cortical projection to brainstem vocal motor neurons, and dependence on auditory feedback to develop and maintain learned vocalizations. These features have so far not been found in closely related primate and avian species that do not learn vocalizations. Male mice produce courtship ultrasonic vocalizations with acoustic features similar to songs of song-learning birds. However, it is assumed that mice lack a forebrain system for vocal modification and that their ultrasonic vocalizations are innate. Here we investigated the mouse song system and discovered that it includes a motor cortex region active during singing, that projects directly to brainstem vocal motor neurons and is necessary for keeping song more stereotyped and on pitch. We also discovered that male mice depend on auditory feedback to maintain some ultrasonic song features, and that sub-strains with differences in their songs can match each other's pitch when cross-housed under competitive social conditions. We conclude that male mice have some limited vocal modification abilities with at least some neuroanatomical features thought to be unique to humans and song-learning birds. To explain our findings, we propose a continuum hypothesis of vocal learning.

Male mice song syntax depends on social contexts and influences female preferences.

In 2005, Holy and Guo advanced the idea that male mice produce ultrasonic vocalizations (USV) with some features similar to courtship songs of songbirds. Since then, studies showed that male mice emit USV songs in different contexts (sexual and other) and possess a multisyllabic repertoire. Debate still exists for and against plasticity in their vocalizations. But the use of a multisyllabic repertoire can increase potential flexibility and information, in how elements are organized and recombined, namely syntax. In many bird species, modulating song syntax has ethological relevance for sexual behavior and mate preferences. In this study we exposed adult male mice to different social contexts and developed a new approach of analyzing their USVs based on songbird syntax analysis. We found that male mice modify their syntax, including specific sequences, length of sequence, repertoire composition, and spectral features, according to stimulus and social context. Males emit longer and simpler syllables and sequences when singing to females, but more complex syllables and sequences in response to fresh female urine. Playback experiments show that the females prefer the complex songs over the simpler ones. We propose the complex songs are to lure females in, whereas the directed simpler sequences are used for direct courtship. These results suggest that although mice have a much more limited ability of song modification, they could still be used as animal models for understanding some vocal communication features that songbirds are used for.

The Diary of Mary McKeon, an Irish American Domestic Servant in Nineteenth Century America

What did young, single, unaccompanied Irish women experience when immigrating to the United States in the late nineteenth century? In this final project, I will explore primary and secondary sources that address their experiences, focusing on a diary written in 1883 by a young Irish domestic servant working in New Haven, Connecticut. Mary McKeon, a sixteen-year-old girl from County Leitrim, Ireland, recorded her experiences as a domestic servant for two different families, as well as her own personal thoughts. Mary wrote down her personal experiences, providing a glimpse of what her life was like both inside and outside of her employer’s home. Though much of my research will show that many young women like Mary would be subjected to prejudice and discrimination due to their lack of understanding middle-class American values, which would give rise to the “Bridget” stereotype of a brutish, ill-mannered and incompetent domestic servant, not all Irish women experienced that discrimination and prejudice. Mary is one example of a domestic servant that was treated kindly by her employers and her story documents a more positive and supportive environment for this newly arrived young, single immigrant. Her diary also reveals her to be a young woman who worked to improve her language skills and her situation. And, through her diary, we get a glimpse of her strategies for ensuring an active social life, including access to courtship and marriage. By analyzing Mary’s diary and sharing my results in this final project, I hope to provide a more comprehensive view into the lives of these young women.