When we think of dopamine, we tend to associate this ‘happy hormone’ with reward and pleasure. But evidence has shown that dopamine is also heavily involved in learning, memory, and even motivation! (Life hack: a good way to motivate yourself to complete a project is to imagine the happiness you will get after completion.) Indeed, dopamine is beginning to be revealed as more and more crucial to our learning, specifically auditory learning. By examining the way songbirds learn to identify and vocalize songs, we can gain a similar understanding of how humans learn and vocalize words.
Recently, researchers at the University of Massachusetts Amherst looked into the role of dopamine in the auditory learning processes of songbirds. In their previous study, they found that, within the auditory brain of songbirds (that is, the region of the brain responsible for auditory processing), there were neurons that produce estrogen whenever the birds were listening to a bird song. In this new study, when they looked further into these estrogen-producing neurons, they found a type of dopamine receptor, D1R, present. Activating or inhibiting D1R affects these neurons’ abilities to communicate with other neurons. This finding suggests that dopamine is an important factor in the functioning of these neurons, at least in the case of sound-learning processes for songbirds.
The researchers also developed a conditioning test for the songbirds that is reminiscent of the well-known Pavlov’s dog experiment. In their experiment, they isolated twenty songbirds and presented them with a random sound recording followed immediately by a silent video of other birds. Then, they looked into the auditory brains of the birds after this conditioning, and found that many genes in the neurons with D1R had different expression levels than before. This is yet another piece of evidence that dopamine, and the neurons that are affected by dopamine, play a crucial role in remembering sounds.
There remains a lot more to be studied as to how auditory learning works in humans, since both the human brain and the sounds we hear are much more complex. However, these results present many clues regarding how vertebrates as a whole could be learning sounds, including humans.
The first author of the study, Matheus Macedo-Lima, is currently a postdoctoral associate in the Neuroscience and Cognitive Science Program at University of Maryland.
Managing Correspondent: Wei Li
Press Article: Role of dopamine in songbird’s brain plasticity, ScienceDaily.
Original Article: Dopamine D1 Receptor Activation Drives Plasticity in the Songbird Auditory Pallium, Journal of Neuroscience.