Male Songbirds Ardently Practice Their Songs Leading Up to Mating Season
The male songbird attracts its female mate through the use of his song. However, before the bird becomes sexually active, it will painstakingly practice its song, adjusting the pitch of some notes, and making certain changes. Their goal is to produce the same song as their father through trial and error. This leads to the bird singing the same tune over and over again, hundreds of times per day. For one bird, the Bengalese finch, this process of honing the perfect song takes 50 days of practice, beginning at the age of 40 days and ending at 90 days. At this point, the male Bengalese finch finally considers himself ready to serenade the females.
A new study from researchers at the University of California, San Francisco (UCSF) examines this process in the finch’s brain. They understood that accomplishing the feat of creating the perfect tune requires the brain to receive and process large quantities of information regarding its singing performance. Then this data must be used to precisely control the complex vocal actions which allow the bird to make the necessary modifications to pitch and song pattern.
The UCSF scientists found a key brain structure that acts as a learning hub where information is received about the song, and direction is given on how to improve it. However, this learning hub does not directly control the action. The scientists believe this insight can be used in developing new ways to treat neurological disorders in humans which impair movements, such as Huntington's and Parkinson's disease.
The key "smart" brain structure is known as the basal ganglia, a cluster of interconnected brain regions dedicated to motor control and learning.
Once a basic, frequently repeated skill is learned, such as typing or throwing a baseball, or for the birds, singing, control of that activity is carried out by the motor pathway. This is the basic part of the nervous system that transmits signals from the brain to the muscles.
But when the basic routine has to change, like trying to throw a knuckleball, or for a bird to sing a different tune, the basal ganglia must be involved. It provides feedback which allows improvement through trial and error.
To prove this theory, the scientists blocked the output of a key basal ganglia circuit in the finches. They observed that the finches were not able to change their tune, even after an unpleasant noise was added to certain notes through use of an audio-reading computer. The bird just couldn’t change or show signs of learning. Once the basal ganglia was unblocked, the finches changed their tune right away.
"It's as if a golfer went to the driving range and was terrible, hitting the ball into the trees all day and not getting any better," said Jonathan Charlesworth, a recent graduate of UCSF's neuroscience PhD program and the first author of the new paper. "Then, at the end of the day, you throw a switch and all of a sudden you're hitting the fairway like you're Tiger Woods."
This study has been published in the journal, Nature
Bird image via Shutterstock