Neuroscientists hope to learn more about what aspects of singing cause these neurons to respond in this way, building on earlier work investigating the relationship between music and the human brain
There are neurons in the human brain that light up when we hear singing, neuroscientists at Massachusetts Institute of Technology (MIT) have discovered, publishing their results in Current Biology.
Found in the auditory cortex, the part of the brain’s temporal lobe that processes sound, these neurons appear to respond to the specific combination of voice and music, rather than just ordinary speech, or instrumentals with no vocals.
“The work provides evidence for relatively fine-grained segregation of function within the auditory cortex, in a way that aligns with an intuitive distinction within music,” said lead author Dr Samuel Norman-Haignere.
These findings build on a 2015 study from the same team, where they investigated the relationship between music and the brain using functional magnetic resonance imaging (fMRI).
In this earlier research, the brain networks of professional composers were explored during music creation. The researchers found that when creating music, composers subconsciously rewire their brain. The parts they don’t need – the neurons that integrate the visual and motor areas – are put to use on another job. It seems these neurons actually get to work enhancing the connectivity to between the two other areas typically responsible for emotion and imagination, the anterior cingulate cortex (ACC) and the default mode network (DMN) respectively. This suggests that when creating music, a specific brain state is formed that enables composers to integrate musical notes with emotion.
And now this new study takes the research one step further. Using a method called electrocorticography (ECoG), where electrodes are placed inside a person’s skull, the researchers have been able to precisely record the electrical activity that occurs in the brain when listening to music.
“There’s one population of neurons that responds to singing, and then very nearby is another population of neurons that responds broadly to lots of music. At the scale of fMRI, they’re so close that you can’t disentangle them, but with intracranial recordings, we get additional resolution, and that’s what we believe allowed us to pick them apart,” said Norman-Haignere.
In combining this data with that from the previous fMRI study, researchers were able to more accurately pinpoint the locations of these neurons that respond to singing.
The difficulty, however, comes with obtaining data using ECoG. Although accurate, it is an invasive procedure that involves placing electrodes directly onto the exposed surface of the brain via a craniotomy (a surgical incision into the skull), and as such, it’s not one that’s typically employed for brain research.
However, ECoG is used to monitor people with epilepsy prior to surgery, to determine where their seizures are originating. During this window a patient can opt-in to other studies that measure brain activity, such as this one.
Neuroscientists hope to learn more about what aspects of singing cause these neurons to light up. It is also hoped they can investigate how (and when) these brain regions develop, by looking at responses in infants.