Singing in the Brain: Neural Responses to Vocal Music

Vocal music such as rock, opera, or choral music can be uniquely compelling—so much so, in fact, that researchers recently asked whether distinctive brain responses can be found in listeners. Their new results, published in Current Biology and authored by Sam Norman-Haigere and others (2022), pinpoint groups of neurons that react to singing in preference to other music or sounds.

The research team observed neural responses to sounds using a method called electrocorticography (ECoG), which allows precise measures of brain activity by placing electrodes directly on the brain’s surface. This method allows the localization of neuronal populations that respond more to singing than to instrumental music or other sounds like spoken words, toilet flushing, or traffic. They combined this with brain imaging by functional MRI to determine the location of these responses.

Recording directly from the brain surface has been used to help guide the surgical treatment of epilepsy after less invasive methods have been tried. The 15 patients studied in this research gave their informed consent to the research as an optional adjunct to the recordings given to guide treatment.

Responses to 165 different sounds were recorded from the surface of the temporal lobe, in or near where responses to simple sounds as well as words and music have been found. Their study identified neuronal populations that responded to vocal music rather than or more than to instrumental music or other sounds.

“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,” said Sophie Scott, a professor of cognitive neuroscience at University College London, in an interview with the Guardian's Nicola Davis. “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 it’s very interesting that some of these distinctions are also seen when we listen to human song.”

Earlier studies asked why music in general, whether vocal or instrumental, can be so enjoyable to so many, more in some listeners than others. There are many possible answers—going back to the ancient Greeks, when the philosopher Plato suggested that music has a direct effect on the soul and Pythagoras described how the sounds of vibrating strings obey mathematical rules and channel "the music of the spheres."

More recent scientific approaches range from the sound frequencies that produce harmony or dissonance to the responses of the nervous system, as discussed in Daniel Levitin's book This is Your Brain on Music: The Science of a Human Obsession. Some neuroscientists focus on connections in the brain—especially between regions that respond to the sound of music and regions that respond to pleasure.

To explore such connections, an MIT-Harvard research team of Sachs and others (2016) devised a scale to identify people who reported strong responses to their favorite music—such as a sense of awe, chills, or goosebumps—with music non-responders. Could there be a neural basis for these differences? The authors focused on brain regions, such as those in the prefrontal cortex and nucleus accumbens, known to respond to pleasurable rewards like food, sex, and drugs, with links to positive social communication as well.

The strength of such connections, described as connectivity, was based on a method known as Diffraction Tensor Imaging (DTI). In their study of 20 individuals, after controlling for other variables, they found that music responders, compared to non-responders, had enhanced connections via nerve fibers between their temporal lobe regions sensitive to music and other sounds, and the regions sensitive to pleasure.

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Music is found in every culture, affecting our emotions, intellect, and psychology. "Together, the present results may inform scientific as well as philosophical theories on the evolutionary origins of human aesthetics, specifically of music: perhaps one of the reasons why music is a cross-culturally indispensable artifact is that it appeals directly through an auditory channel to emotional and social processing centers of the human brain," the authors wrote. As they suggested, music may have evolved as a way of sharing in an activity that enhanced social connections and helped to heighten as well as regulate emotions.