MIT study finds neurons in epilepsy patients that only respond to singing

A study by MIT scientists on a group of epilepsy patients discovered that a specific group of neurons in their brains respond only to singing — and not to instrumental music or any other type of sound. The findings of the study were published today in the science journal Current Biology. Scientists are still working to nail down the implications of the study for epilepsy patients, some of whom rely on music as a form of therapy to reduce seizures.

“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,” says Sam Norman-Haignere, the lead author of the study and assistant professor of neuroscience at the University of Rochester Medical Center.

Given how small and specific the study’s sample size is (fifteen people), there’s not much we can conclude from this single study alone. But it will likely advance further studies on the link between neuroscience, epilepsy and music in the future.

The study’s participants were a group of fifteen epilepsy patients, all whom consented to have electrodes implanted in their skull. They were then asked to listen to hundreds of different sounds, both natural and synthesized. Scientists, assisted by fMRI, or functional magnetic resonance imaging, observed how neurons in the auditory cortex of participants reacted to each sound.

Back in 2015, the same researchers used fMRI imaging to identify what they believe are a group of neurons that respond only to music. 

The neurons only elicited mild reactions when hearing the sound of human voices, but fired up at the sound of instrumental or vocal music. In the new study, the researchers found that there was a special subset of neurons right next to the original group that specifically lights up when the brain hears human singing.

“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,” says Norman-Haignere.

The research could also advance our understanding of the link between music and epilepsy. While certain kinds of music can reduce the number of seizures that epilepsy patients suffer from, some rare cases of epilepsy can also be provoked by music. One recent study published in Scientific Reports last year found that listening to 30 seconds of Mozart’s “Sonata for Two Pianos in D Major” helped drive down the neuron activity that causes seizures in epilepsy patients.