Some Neurons in the Brain Selectively Respond Only to Sound of Singing

Scientists on Tuesday announced they had found an unexpected response to singing in the brain, suggesting particular groups of neurons appear to respond selectively to these particular sound.

In a Current Biology journal article, a team of scientists in the United States report that they made their discovery by recording electrical activity in the brains of 15 participants, each of whom had electrodes inserted inside their brains to monitor epileptic seizures before undergoing surgery.

The team recorded electrical activity in response to 165 different sounds, including pieces of instrumental music and speech, then processed them using an algorithm. Combined with results from fMRI brain scans collected from 30 different individuals, they mapped the location of patterns in the brain.

Data gives insight into singing and the brain

“fMRI is one of the workhorses of human cognitive neuroscience, but it is very coarse,” says Dr. Samuel Norman-Haignere, a co-author of the study who is based at the University of Rochester. “Intracranial data is much more precise but has very poor spatial coverage.”

The results, which confirmed previous findings from fMRI scans that some neurons respond only to speech or respond more strongly to music, revealed populations of neurons appear to respond selectively to the sound of singing, with only very weak responses to other types of music or speech alone.

The neurons are located in the superior temporal gyrus

Authors of the study speculated that the “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 song.”

These song-specific neurons appear to be located in the superior temporal gyrus, close to areas previously identified as responding particularly to music or to speech.

“This work suggests there’s a distinction in the brain between instrumental music and vocal music,” Norman-Haignere said.

An even bigger mystery is why we would have such neurons in the first place, however.

“It could have been due to some evolutionary role,” Norman-Haignere said. “Many people think that singing has some important role in the evolution of music.”

Means of survival?

“To be able to distinguish the musical properties of sounds is fundamental for survival,” states Jörg Fachner at Anglia Ruskin University in Cambridge in the UK. “It makes sense that this dispositional ability is wired into our auditory cortex.”

The researchers add work is now under way to understand what it is about singing that these areas of the brain are responding to, such as whether it is pitch and timbre, or melodies and rhythms, while they also hope to explore how such selectivity arose during development or evolution.

First step to understanding singing and the brain

“Our study presents a first step toward answering these longstanding questions,” the study authors said. However, they also raise the possibility of studying the impact of activating areas of the brain related to songs and exploring interactions with other parts of the brain, noting that songs can elicit particular emotions or memories.

“It may also explain why singing a beloved song to a person with dementia may allow responses (even though) the neurodegenerative process has limited the functionality of brain areas,” Fachner said. “This result, along with other neuroimaging-related results of musical memory, may help to explain why songs may help dementia patients.”