While music has been crucial to culture throughout history, how the brain perceives and appreciates music has remained clouded.
How the Brain Appreciates Music
Now, researchers have come up with an accurate map of what takes place in the cerebral context when a person listens to a melody.
It turns out that the brain does two things at the same time. It follows a note pitch using two neuron sets that also follow a speech pitch. At the same time, it also tries to predict the next notes using a neuron set that is unique to music.
The findings were noted in the "Encoding of melody in the human auditory cortex" study. The study sheds light on long-standing mysteries regarding how the auditory cortex of the brain processes melody.
Edward Chang, MD, neurosurgery chair of UC San Francisco and a member of the Well Institute for Neurosciences, explains that they observed that how a person understands melody is somewhat entwined with how a person understands speech, though some crucial aspects of music stand on their own.
Pitch and Predictions
The first two neuron groups were apparently the same ones that Chang identified back in 2017. These neurons were found to be involved in processing vocal pitch changes that lend emotion and meaning to speech.
However, the third neuron group was devoted solely to melodic tone predictions. They were described in the new study for the first time.
The team of Chang knew that something similar took place for speech, as specialized auditory cortex neurons anticipate the next sound, or phoneme, in speech. This is based on what the brain learned about the words and the context.
The scientists hypothesized that a similar neuron group could exist for melody predictions. The team tested this on eight volunteer participants during their surgical epilepsy workup. They recorded the auditory cortex's direct brain activity as the participants listened to different melodic phrases from Western music. The participants then listened to sentences that were spoken in English.
Their hypothesis was found to be correct, as the recordings revealed that the brains of the participants used the same neurons for assessing pitch quality in both music and speech. However, each mode had unique neurons that were designated for prediction.
This means that the auditory cortex was not just looking for notes. It also had some specialized neurons that were trying to predict the next note using what is already known about melodies.
Chang explains that when a person listens to music, two things happen at the same time. The melody's individual notes go through low-level processing, while high-level processing also takes place for the notes' context.
According to Narayan Sankaran, PhD, a postdoctoral scholar of the lab of Chang and who was the leader of the study, this makes sense as the brains evolved to anticipate further information. Listening to a certain melody could affect emotions as the auditory neurons that process music engage with the brain's emotional centers.
Sankaran explains that composers speak of musical resolution and tension. The ability of the brain to anticipate and expect such musical features shows how it can set an emotional or upbeat mood.
However, there is still a lot of mystery surrounding these connections. Sankaran explains that it is clear how music enriches the intellectual, emotional, and social aspects of lives and could treat different conditions. Sankaran adds that in order to know why music yields such benefits, it is necessary to answer some fundamental questions regarding how music works within the brain.
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