© Hiroyuki Ito/Getty ImagesHow does music evoke goosebumps and spine tingles?
With the passing of time comes new technology though, and suitably equipped with modern brain scanning equipment, scientists may now have made some headway.
In the latest effort to understand "the chills", researchers in the US put out a call for music fans who either consistently experienced euphoric sensations on hearing certain tracks, or who hardly ever felt them at all.
"It stemmed from a deep interest in intense, profound emotional responses, in particular those that come from music," said Matthew Sachs, a graduate student at the University of Southern California who conducted the experiments at Harvard University. "I've always been fascinated by how a collection of tones changing over time has the ability to evoke these very strong sensations."
More than 200 people responded to the call and filled out online personality questionnaires. From these, Sachs and others at Harvard and Wesleyan University in Connecticut selected 10 to form a "chill group" and another 10 to form a "no chill" group.
Before having their brains scanned, the 20 volunteers went into the lab with playlists of music they found most pleasurable. The tracks ranged from theLiebestod from Wagner's Tristan and Isolde and Coldplay's Strawberry Swing to Bag Raiders' Shooting Stars and Blue Devils Drum Corps's Constantly Risking Absurdity.
Using a battery of tests, the researchers measured the volunteers' physiological responses to the music they brought in and other tracks chosen to act as controls. The tests allowed the team to confirm that even though all of the participants were self-professed music fans, only half regularly experienced the curious sensation of the chills.
Next, volunteers had their brains monitored using a brain-scanning technique called diffusion tensor imaging (DTI). The procedure shows how connected different regions of the brain are, and so how good the neural communication is between them.
When Sachs looked at the scans from the "chill group" and the "no chill group", he noticed differences in how three key regions of the brain were connected. The brains of people who felt the chills had more nerve fibres running from the auditory cortex, needed for basic hearing ability, to two other regions, namely the anterior insular cortex, involved in processing feelings, and the medial prefrontal cortex, which is thought to monitor emotions and assign values to them.
The work, published in Social, Cognitive and Affective Neuroscience, is at an early stage. But if the results stand up, they may reveal how music can have such a curious effect on human physiology. "The chills is a sensation we get when we're cold. It doesn't really make sense that your hair would stand on end, or that you'd get these goosebumps in response to music," said Sachs.
"We think that the connectivity between the auditory cortex and these other regions is allowing music to have that profound emotional response in these people," he added. "It's very hard to know whether or not this is learned over time, or whether these people naturally had more fibres. All we can say is there are differences that might explain the behaviour we see."
Robert Zatorre, a neuroscientist at the Montreal Neurological Institute at McGill University, said the results were valuable for those hoping to understand music's pleasurable effects in the brain. "Some people seem particularly sensitive to music, showing not only a lot of interest and liking of music, but also displaying physiological responses to music, such as the very pleasurable 'chills'," he said.
That people who feel the chills have stronger connections between the brain's auditory system and areas related to emotions fits well with results from Zatorre's lab. He found that when listening to highly pleasurable music, the auditory system is strongly coupled to the brain's emotion and reward systems. "The two pieces of evidence together indicate that this interaction, between auditory and emotion systems, is the basis for musical pleasure, and that people who get more of a direct "thrill" from music have a stronger connection," he said. Understanding why people feel such intense emotions is one thing. Whether science can ever help musicians to induce the chills remains to be seen.
Comment: Why do only some people get 'aesthetic chills' from listening to music?