Part of sparrow's brain massively expands in preparation for mating

When it’s time to find a mate, the parts of songbird brains that are responsible for singing get bigger — and then shrink down again at the end of the season. But none do it quite like the Gambel’s white-crowned sparrow (Zonotrichia leucophrys gambelii). In males of the species, a brain area called the HVC nearly doubles in size, expanding from 100,000 neurons to 170,000. How the bird pulls off this feat is still a mystery — but it might one day point to ways of treating anomalies in the human brain.