Vibrantly colored zebra finch males sing to attract a mate. Females display a more muted plumage and do not sing. These difference between the sexes have inspired a great deal of sexual dimorphism research in the species. In the embryo the male zebra finch produces estrogen which is transformed into a testosterone-like hormone in the brain. This difference leads to the development of a song system in the male nervous system but not in the female. Even with the song system in place the male zebra finch must learn to sing. The young bird works on matching his singing to the memory of his father’s song. Most males will sing their father’s song with little variation but they may also incorporate sounds and songs by other males they come in contact with. Because of these attributes (and others) zebra finch males have played an important part in research on learning, memory, and development.

Recent studies have shown that a small fraction (about 7%) of laboratory raised male zebra finches stutter. Stuttering consists of a variant of the birdsong that contains three or more successive repetitions of song syllables, usually the last syllable in a sequence. About half of juvenile male zebra finches learn to reproduce the stuttering when they are tutored by a stutterer whereas the other half resist stuttering despite having a stuttering tutor. The authors of a recent paper (“Altered Auditory BOLD Response to Conspecific Birdsong in Zebra Finches with Stuttered Syllables” published December 23, 2010 in PLoS ONE) asked if there is any alteration in sensory song representation in the brains of birds that stutter.

To investigate, the team used functional magnetic resonance imaging (fMRI) on awake zebra finches presented with songs. All of the subject birds where normal but were tutored by stuttering birds. The tutored subjects fell into two groups; those who mimicked the stuttering and those who did not stutter. They found that the pupils who stuttered showed significantly reduced responses to their tutor’s song and enhanced responses to unfamiliar songs. The results are the first evidence for a neural correlate of song representation in birds that, after learning songs from a stuttering tutor, have a tendency to stutter themselves. It will be interesting to see if stuttering zebra finches can help provide insights into the neurodevelopmental basis of stuttering in general.


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