To Tweet or Not to Tweet

By Sam Russell

Have you ever wondered why birds of the same species tweet identical songs? A recent study has connected the levels of dopamine, a neurotransmitter, to the song that a bird sings. A neurotransmitter is a chemical that is released at the end of a nerve cell to send messages to another nerve cell or neuron. Dopamine is an important neurotransmitter that is triggered by rewards and helps encourage a certain behavior or action to be performed. When people eat delicious foods or quench their thirst, there is a spike in dopamine signals.

A baby bird learning to sing is similar to a human baby learning to talk. Baby birds start learning how to sing by babbling. Usually a baby bird will learn from its father, listening and memorizing the song to perfection. How does a bird’s dopamine level help contribute to learning the perfect song? A neuroscientist and his team recently studied this very question.

The Experiment

Jesse Goldberg is a neuroscientist at Cornell University in Ithaca, New York. His interest in connecting dopamine levels and the songs of zebra finches started with an experiment that placed the finches in special chambers that had microphones and speakers to record their songs. After the recordings were made, the songs were played back for the birds to hear.

Tiny recording wires were inserted into the birds' brains to measure the activity of dopamine-making cells. The song of each finch was played back either normally or with a slight change in pitch to detect if there was indeed a change in dopamine levels.  

The Results

Goldberg and his group of researchers found that when the song of each zebra finch was played back normally, the dopamine-making cells showed a small amount of activity. But when the song was played back at a change in pitch, there was a large drop in dopamine. The drop in dopamine levels indicated that the messages were not being transmitted or, in this case, that the song was not going to the brain.

Goldberg hypothesized that the dopamine system (in birds specifically, as well as other animals), is used to help indicate whether an action or signal is correct or not. The results Goldberg and his team found with dopamine spikes and declines based on the zebra finch song playback may help scientists understand how humans learn.