Neurosurgeons have learned how the brain "reads" music
American doctors have managed to determine how the brain decodes melodies, "anticipating" certain notes. According to the researchers, these processes explain why music can make us happy or bring us to tears.
Music perception is measured by several pitch-based parameters: the absolute pitch of notes, the difference in pitch between successive notes, and the expectation of each note given the preceding context. How our brains measure these parameters and how different it is in processing melody versus speech is a very murky area of knowledge, with very little data available.
Scientists from the University of California (USA) decided to clarify the issue and studied how the brain decodes the information encoded in music. Their findings are presented in the journal Science Advances.
In 2017, the same experts studied how the brain processes information about changes in voice pitch, which gives speech meaning and emotionality. The researchers also knew that specialized neurons in the auditory cortex anticipate the next speech sound or phoneme based on what the brain has already learned about words and their context. This is similar to the workings of the T9 system, which anticipates typing on a cell phone.
Neuroscientists hypothesized that a similar group of neurons must exist in our brains to process and predict a particular sound in a melody. The study involved eight subjects who volunteered to have their brain function measured while undergoing epilepsy surgery.
During the surgery, the participants listened to music and then to speech (in English). It turned out that the participants' brains used the same neurons to assess pitch quality in both speech and music. Different groups of nerve cells were responsible for the prediction in speech and music.
This means that the brain's auditory cortex didn't just "search" for notes - it has a specialized set of neurons that can predict which notes will be next in a melody. To do this, the brain uses its knowledge of songs it has already heard - musical patterns.
"When we listen to music, two things happen in our brain: low-level processing of the individual notes of the melody, and then high-level abstract processing of the context of those notes," Edward Chang, M.D., one of the study's authors, told the researchers.
According to the scientists, it is this ability to anticipate and anticipate particular notes in music that explains how it can either make a listener feel optimistic or bring them to tears. This is due to a certain tense expectation that is "resolved" by anticipating sounds. As the researchers suggested, the brain has acquired this ability because it is evolutionarily "sharpened" to anticipate information coming from outside.