Everyone is familiar with the concept of “warming up” before doing some kind of practiced task. For example, a guitar player may play a few scales before a concert, or a golfer may take a few practice swings before stepping up to the tee. Surprisingly, a recent study has shown that songbirds also warm up before singing!
The Zebra finch is a songbird native to central Australia and parts of Indonesia. Neuroscientists have used these cute little guys for years to study vocal learning. Female zebra finches typically have muted grey coloring and a bright orange beak. Males, have brightly colored cheek feathers and colorful patterns on their chest and wings. When male zebra finches reach puberty, they learn a song that they will use to attract mates! Normally, young male zebra finches learn their song from an older male “tutor.” This makes zebra finches a great animal model of vocal learning for neuroscientist! Zebra finch song consists of a stereotyped repeated phrase, called a motif. A motif is similar to a word, in that it can be broken down into smaller syllables and notes. However, unlike humans that learn thousands of words, male zebra finches learn to sing a single motif used to attract mates. The birds repeat their motif in quick succession, called bouts. But before beginning their song, the zebra finch might sing a few simple notes that are different from those in the motif. These are called “introductory notes,” because they precede the bout.
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The purpose of these introductory notes has long been open to speculation, but a study published in Current Biology has found evidence that these notes help the bird warm up their vocal organ and their brain before beginning their song! The number of introductory notes before a bout can vary, and interestingly, the number does not correlate with the length of the subsequent bout. Rather the number of introductory notes correlates with the amount of time since the last bout! Just like the guitar player who hasn’t played in a while may take more time to warm up, the longer it has been since the last time the bird sang, the more warming up it needs to prepare. The quality of each introductory note before a bout starts off poor, but gets better as the bird leads up to the onset of the first motif. The last note before the first motif is very consistent across multiple renditions, suggesting that it is used as a cue signaling that the bird is ready to sing.
The same thing happens in the brain, in a region called HVC, which is responsible for sequencing and timing notes. The neural firing pattern in HVC is always the same during the last introductory note before the first motif. This suggests that the bird is getting his brain, as well as his muscles, ready to sing! This is especially important when the male sings directly to a female (rather than by himself), because the female will judge the male’s attractiveness based on his singing. When singing directly to a female, the male sings more introductory notes before each bout, and ramps himself up by reducing the duration of the gaps between successive introductory note.
These findings suggest that learned behaviors, like zebra finch song, might require some initial practice to achieve the neural state needed for performance. This phenomenon in songbirds likely shares some of the neural basis with learned activities in humans, as well as in other animals. So before your next performance, take a lesson from the birds, and warm up your brain!
Rajan R. & Doupe A. (2013). Behavioral and Neural Signatures of Readiness to Initiate a Learned Motor Sequence, Current Biology, 23 (1) 87-93. DOI: 10.1016/j.cub.2012.11.040
Escrito por Michael C. Condro, Ph.D.
Special thanks to Jon Heston for the birdsong example.