The idea of music is present in all human societies. While other creatures also display musical behavior, like bird songs, or humpback whale calls, our ability to engage with music sets us apart in the animal kingdom.
A recent study sheds light on how the brain perceives music, revealing that singing triggers distinct neural activity compared to speech or instrumental music.
Scientists, for the first time, have identified a specific type of neuronal cell in the human brain that responds exclusively to singing, not reacting to other musical forms.
These cells, located in the auditory cortex, seem to react to particular combinations of human voices and music, excluding responses to normal speech or music produced by instruments.
Studying the brain isn't a simple task. To gain an accurate understanding of the brain's response to sound, researchers use a technique called cortical electroencephalography (ECoG), placing electrodes inside the skull to record the brain's electrical activity.
ECoG data is more precise than other methods for measuring brain activity. Electrodes, directly on the brain, measure electrical activity, not just blood flow (as done with functional magnetic resonance imaging or fMRI), providing more insight.
Implanting electrodes directly into the brain constitutes an invasive procedure. Researchers collected data for several years from epilepsy patients who had undergone surgery to treat their seizures.
Electrodes were placed inside the scalps of these patients to monitor neural activity before surgery, allowing them to participate in studies recording brain activity during specific tasks.
In this study, participants listened to 165 common sounds during the monitoring period, from cell phone vibrations to pouring liquids, talking, and typing. Among these sounds were vocals with and without background music.
Remarkably, the researchers discovered a unique cluster of neurons responding specifically to singing, distinct from more generalized neural representations of instrumental and speech sounds. They theorized that singing's characteristics create a unique category, necessitating its neurodynamic signature.
Singing is set apart from speech by its melodic pitch contours and rhythmicity. Additionally, it differs from instrumental music through vocal resonance and other speech-specific structures.
The researchers suggested that song-selective neural populations nonlinearly integrate multiple features distinguishing singing from speech, such as melodic intonation and vocal resonance.
The researchers merged their ECoG data with fMRI data from a previous study using the same methodology. This integration provided a more comprehensive understanding of the location of neural activity.
This study enhances neuroscientists' comprehension of how our brains represent music. While questions about how music and songs' selectivity on the nervous system emerged during evolution persist, the new technique of combining ECoG and fMRI data could aid future studies in answering these questions.
