To attract a female's attention, a male songbird needs to woo her with his courtship song. However, male songbirds aren't born pre-programmed with this song and have to learn it by mimicking their kinsman's songs, in much the same way us humans learn to speak. Just like us, practice makes perfect, and male songbirds will often practise every morning. But how exactly does practising help? It's a question that interests Stephanie White, a neuroethologist from the University of California Los Angeles, USA: ‘We're interested in how the brain controls behaviour and how behaviour affects the brain.’ In humans, the ability to speak properly relies on two important transcription factors, FOXP1 and FOXP2, which regulate the expression of other genes. It seems that it's the same in birds, as knocking down FoxP2 levels prevents them from accurately copying their tutors' melodies. But is FoxP2 involved after initial learning? From her previous work, White knew that expression of the FoxP2 gene decreased when zebra finches practised their songs, but wondered whether this happened in other birds (p. 3682).
White recruited her graduate student, Qianqian Chen, onto the project and the pair decided to see what happened to FoxP2 levels in Bengalese finches. White explains that these finches were originally bred from white-rumped munia for their colourful plumage: ‘That freed up the male from needing to keep his song recognisable to the female in the wild, to evolving to her preference for more interesting songs.’ Comparing them with zebra finches, which have predictable songs that follow a strict musical ‘score’, White says: ‘Bengalese finches have beautiful phrases [songs] that in the middle can go one way or the other. Their song is less stereotyped and stuck in adulthood, so we wanted to know whether FoxP2 variation would be more dramatic in them because they retain this greater flexibility in their song in adulthood.’
A week before the experiment began, Chen placed her male Bengalese finches into sound-attenuating chambers. On the day of the experiment she woke her birds up at 8 am and let half of them serenade the room as they practised their tunes. To prevent the other half from practising, Chen would keep a close eye on them, distracting them if they looked as if they were about to burst into song. At various time points: 1, 1.5 and 2 h, Chen would then collect brain samples to analyse for FoxP2 expression.
As with zebra finches, the team found that FoxP2 levels in Area X (the brain region involved in song learning) did decline after 1.5 h, confirming that FoxP2 plays an important reinforcing role in perfecting and maintaining courtship songs in birds. However, White recalls that this decline was: ‘Surprisingly not more rapidly nor to any greater degree than in zebra finches. Which left us wondering, had we properly controlled for this bird's behaviour?’ Sure enough, the Bengalese finches weren't as chirpy as their distant zebra finch relatives, and sang half as much during the entire trial. Unfortunately, because of circadian rhythms, the team couldn't extend the trial time, but by extrapolating from their data they think that FoxP2 levels wouldn't go down any further or any faster than in zebra finches, despite the Bengalese finches' substantial musical repertoire. It's clear that FoxP2 is a key player in this cycle of practice and performance and it's likely to be the same for us, as White explains: ‘With these trial and error types of behaviour, you can't just pick them up once, you have to keep them up, and you're basically fine-turning your own levels of genes in the brain.’