Babies learn to speak by reproducing the sounds they hear from their parents. Birds use a similar principle - for example, finches hum their songs to chicks so that they form the desired acoustic pattern in their memory. Further, having become adults themselves, they will repeat the sounds already to their chicks. Researchers at Texas Southwestern University intervened in this process - and managed to give the finches a false memory of sounds that they had never heard.
For their own purposes, scientists have used a new technology - optogenetics. By spotlighting specific areas in the bird's brain, they stimulated the activity of individual neurons to form new connections between them. And the memory of living beings is a collection of such interneuronal connections. Scientists calculated a map of the location of neurons to encode the memory of a new combination of sounds, and then reproduced this structure in the brain of the experimental bird. And after the operation, she sang a song unknown to her.
Optogenetics is a difficult technology to apply, primarily due to the scarcity of our knowledge of how memories are formed. The new bird song was like a Morse code, a primitive alternation of long and short beeps. Scientists do not yet know how to encode the tonality, pitch and order of sounds, how to make a composition truly complex and beautiful, so that it resembles a real bird song. Work in this direction is just beginning.
Map of avian neurons that were activated during the experiment