A team of researchers at the Massachusetts Institute of Technology in the United States has successfully identified neurons in the human brain that respond exclusively to singing, rather than other forms of music.
The study revealed that neurons located in the auditory cortex of the brain respond when a person listens to a mix of melodies and sounds, but do not react to sounds or music in isolation. Researchers assert that these cells become active when engaged with songs, although precise understanding of their function requires further study and investigation.
Sam Norman-Haigner, a neuroscience professor at the University of Rochester Medical Center in New York and a former graduate student at MIT, states that this study demonstrates a subtle difference in the functions of the cells within the human auditory cortex.
The researchers relied on a previous study from 2015 that explored the functions of neurons within the auditory cortex using functional magnetic resonance imaging (fMRI). At that time, the research team found neurons that react to music sounds and measured electrical signals on the brain's surface to obtain more precise information.
Norman-Haigner explains, "There is a group of neurons that respond to singing, alongside other neural groups that respond to music in general. When using fMRI, these groups appear highly intertwined, making separation difficult, but after conducting intracranial recordings, we could observe with much higher precision, and I believe this allowed us to distinguish the different categories of neurons within the brain."
In the framework of the new study published in the scientific journal *Current Biology*, the researchers utilized a new technique known as "electrocorticography" which enables the recording of electrical activities of brain cells by placing electrodes inside the head. This method can measure brain electrical activity with greater precision compared to fMRI, which detects blood flow in the brain to infer neuronal activity.
It is known that electrocorticography is not considered a conventional imaging technique for the human brain as it falls under surgical procedures and is often used to monitor patients with epilepsy facing surgery for seizure treatment. Patients are observed over several days to help doctors determine where seizures originate in the brain. During this stage, participants, with their consent, took part in tests measuring brain signals while performing specific tasks.
The MIT research team collected data from 15 patients over several years, aiming to utilize this information to identify cells that respond to songs in the brain. During the study, researchers exposed patients to 165 sounds that had previously been used in the fMRI experiment.
The experiments indicated that some electrodes within patients' auditory cortex picked up electrical signals, whereas others did not show responses when listening to the sounds. The researchers were able to use a statistical analysis system to pinpoint the locations of the neurons emitting these responses based on the positions of the implanted electrodes.
Norman-Haigner expressed in statements reported by the website *SciTech Daily*, a scientific research platform, that "when we applied this method to the available data, we determined where the neurons that respond to songs are located." He emphasized, "We did not expect to reach these findings, but this is what justifies scientific experiments – discovering new things you had not thought of in the first place."
The researchers indicate that the area responding to song sounds in the brain is located at the top of the temporal lobe, near regions associated with language and music. They hope to learn which types of songs excite these neurons and to determine if children have specific regions in their brains for recognizing different types of music and singing, in an effort to define the period during which these cells develop throughout various stages of human growth.
