Although it has yet to be featured in a West End musical, scientists claim to have discovered an unexpected brain response to singing.

According to the researchers, some groupings of neurons appear to respond selectively to the sound of singing.

A group of scientists from the United States, published its findings in the journal Current Biology after recording electrical activity in the brains of 15 people who had electrodes put within their skulls to monitor epileptic convulsions before surgery.

The scientists used an algorithm to evaluate the electrical activity in reaction to 165 various sounds, ranging from instrumental music to speech and sounds like dogs barking.

To map the position of the patterns in the brain, they coupled the results with data from fMRI brain scans previously obtained from 30 other individuals.

The team opted to mix the data from the various ways to overcome their separate limitations and combine their strengths, according to Dr. Samuel Norman-Haignere, a co-author of the paper from the University of Rochester.

“fMRI is one of the workhorses of human cognitive neuroscience, but it is very coarse. Intracranial data is much more precise but has very poor spatial coverage,” he said.

How do neurons respond to singing?

The findings backed up previous fMRI scan findings that some neurons respond just to speech or respond more strongly to music. They did, however, uncover groups of neurons that appear to respond exclusively to the sound of singing, with only mild responses to other types of music or speech.

“These results suggest that representations of music are fractionated into subpopulations selective for different types of music, one of which is specialized for the analysis of the song,” the team writes.

These song-specific neurons appear to be located in the superior temporal gyrus, adjacent to locations previously identified as responding to music or speech in particular.

The song-selective neurons were likely missed in prior studies using fMRI scans alone, according to the authors, because electrodes allow for finer-grained measurements of cell activity.

The researchers say they're now trying to figure out what it is about singing that these brain areas respond to – whether it's pitch and timbre, melodies and rhythms, or something else entirely – as well as how such selectivity arose throughout development or evolution.

“Our study presents a first step toward answering these longstanding questions,” the authors write.

They also highlight the idea of examining the impact of song-related brain activation and exploring relationships with other brain areas, noting that songs can stimulate certain emotions or memories.

Singing voice vs. Speech

Sophie Scott, a professor of cognitive neuroscience at University College London who was not involved in the research, welcomed the study.

“The singing voice is the only musical instrument that almost everyone is born with, so one might expect us to have a rather different relationship with human song, relative to other kinds of music,” she said.

“We know that there are some significant differences between the brain systems that control how we speak and those that control how we sing, so, interestingly, some of these distinctions are also seen when we listen to human songs.”

Dr. Ediz Sohoglu, a cognitive neuroscientist at the University of Sussex, said the findings were striking.

“One of the interesting questions that arise is why the brain has evolved or been shaped by experience to develop such specialized neurons. Why not just use the same neurons in a multi-purpose fashion to process more than one type of sound?” he said.

“One possibility is that having specialized neurons helps a listener to focus on certain sounds in noisy environments. For example, if I am listening to my favorite singer in a concert, I might find it easier to ignore the loud conversation behind me – which would be represented in a different part of my brain.”