Saturday, October 13, 2012

A new vocal learner found?

'Singing' male mouse.
In a recent study by Timothy Holy and Zhongsheng Guo (Washington University) it was suggested that male mice produce vocalizations that are songlike, in the sense that they have a melodic structure, sequential and repetitive use of ‘syllables’ (as opposed to what can be called ‘calls’) that are combined in a non-random fashion with repeated motifs. And all this in the ultrasonic domain.

Example of a male adult mouse song (from Arriaga et al, 2012).

This discovery opened the question of whether mice share any behavioral and neural mechanisms for song production and learning with the set of rare vocal learning species, which includes three groups of birds (songbirds, parrots, hummingbirds) and several groups of mammals (humans, cetaceans [dolphins and whales], bats, elephants, and pinnipeds [sea lions and seals]).

In a study that appeared in PLoS ONE two days ago, co-authored by Gustavo Arriaga, Eric Zhou and Erich Jarvis (Duke University), it was shown that a motor cortex region in mice is active during singing, and that it projects directly to brainstem vocal motor neurons that is necessary for keeping song more stereotyped and on pitch.

The Jarvis research team also discovered that the 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.

It was concluded 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. In short: vocal learning seems not so much a species-specific characteristic, present in three groups of birds and several groups of mammals, but more likely to be a continuum.

ResearchBlogging.orgHoly TE, & Guo Z (2005). Ultrasonic songs of male mice. PLoS biology, 3 (12) PMID: 16248680

ResearchBlogging.orgArriaga, G., Zhou, E. P., & Jarvis, E. D. (2012). Of Mice, Birds, and Men: The Mouse Ultrasonic Song-system Has Some Features SImilar to Humans and Song-Learning Birds PLoS ONE, 7 (10) : 10.1371/journal.pone.0046610

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