Think back to that moment when you first heard your favorite song. What about it made you stop in your tracks? Was it the incessant buildup, soaring high, filling you with a sense of elation? The flirty high notes, light as wings, bringing a bounce in your step? Or the rumbling base drop, furiously cascading, sending shiver after shiver down your spine?

(For me, it’s this. Brrrrr)

Music moves us, both literally and figuratively. The relationship between music, movement and mood is so fundamental that they’re often described by the same set of words in many languages: we sway to “heart-wrenching” ballads; sprint to “angry” rock n’ roll. The ability to enjoy music across modalities seems to be a unique yet ubiquitous human trait; across the globe people describe intense pleasure from listening to music, grooving to music, exercising to music. What lies at the core of this abstract euphoria? What is it about our perception that allows us to experience all three in unison?

Appraising a musical “high”

I, like many, find myself attracted to bittersweet love tunes after a breakup. As Adele’s laments of broken love engulf my own pain, somehow I experience a paradoxical feeling of relief or even pleasure, perhaps from “letting it out”.

Regardless of what emotions a musical piece conveys, listening to music in and of itself is undeniably pleasurable. Unlike food or sex, music is not intrinsically valuable to the humankind; regardless of what Shakespeare may have lead you to believe, moonlight serenades are not required for survival of our species. Yet, how is music – something so intangible, so “useless”- capable of triggering such profound feelings of euphoria across cultures and generations since prehistoric times?

A few years ago, in an attempt to unravel the mystery, researchers from Montreal monitored the brain’s reward system of volunteers as they listened to music that gave them the “chills”. To visualize changes in the brain, researchers injected the volunteers with a radioactive ligand that binds to receptors of dopamine, a neurotransmitter that mediates the pleasurable effects of natural and drug rewards. As music gradually built up, edging closer and closer to the climax, dopamine flooded the right caudate nucleus, correlating with the listener’s experience of anticipation. At the moment of the “chills”, dopamine rushed out from the synapses of neurons in the right nucleus accumbens (NAc). This intangible mental “high” accompanied a measurable physical response – increased heart rate and sweating, rapid breathing, and a drop in skin temperature – all physical signs of emotional arousal.

It seems rather clear-cut that music feels good because it triggers a dopamine rush. Yet the story, like most of science, is not so simple. Dopamine is released during presentation of the reward, or (as learning occurs) in anticipation of reward. For a familiar piece of music, the theory fits our understanding of pleasure – we squirm at the edge of our seats, anticipating the chills; but how can dopamine release explain our appreciation for previously unheard music?

In a new series of experiments, the same researchers studied how the brain values a newly encountered piece of music. Using an iTunes-like interface, they first played for the volunteers a short clip of an unfamiliar song, and then asked them how much they’re willing to pay ($0, $0.99, $1.29, or $2) to buy the entire tune. Compared to relying on subjective rating, this design allowed researchers to put an objective number on the “value” of music.

The researchers painstakingly screened 126 participants before recruiting 19 people who shared similar musical preferences. This ensured that the same sample clips could be used as stimuli. Then came the hunt for appropriate songs – and it was no easy feat. The songs had to fit two criteria: they have to be “good enough” to entice the participants to buy some of them with their own money; they also had to be unfamiliar to all 19 participants. After putting music recommendation sites (Pandora and Last.fm) to good use, researchers further perfected their music list by consulting local music scores and music blogs; 60 songs were finally chosen.

To monitor changes in the volunteer’s brains as they listened to the samplers, researchers used fMRI, which measures activity through local changes in blood flow. When volunteers encountered a song that they desired, their right NAc lit up (just like in the previous study); the more they were willing to pay for a song, the stronger the activity. The NAc is often associated with “positive” surprise, that is, it activates when you encounter something more rewarding than you originally anticipated.

At the same time, functional connectivity increased between the NAc and brain regions involved in emotional processing and value-guided decision-making, showing that the brain is keeping track of and constantly reappraising new music as it plays. Finally, desirable songs increased connectivity between the NAc and auditory brain areas; the relationship was so strong that the degree of increase could predict the level of desirability for a certain individual.

Together, these results suggest that the NAc responds not only to familiar and pleasurable songs, but also to new songs that “fit” our taste for music. Based on our previous experiences with enjoyable music, we form an understanding of the types of music structures we prefer and generate models of what “good” songs sound like. When we listen to something new, our brain tracks the song and matches it to these internal musical templates – if the song surprises us in an enjoyable way, the reward circuit responds by encoding a sense of pleasure; if not, we experience distaste.

It’s a beautiful theory, though still in its infancy. How do we first generate musical templates? How do some songs, neutral or unpleasant when first encountered, manage to grow on us with time? How is music so variable cross cultures, yet universally loved at the same time?

How, as a species, did we develop a love for this beautiful intellectual reward?

Music and movement: synesthesia through emotion

One theory proposes that our cognitive connection to music evolved from a more ancient skill – the ability to express emotion through movements. While seemingly unrelated on the surface, music and physical motion share many spatiotemporal characteristics – speed, rhythm, smoothness – that engage the same brain circuits, particularly ones involved in time-keeping, learning of sequences and motion perception.

In one clever experiment, researchers asked college students to try to express a given emotion by either creating a melody or an animation of a ball bouncing on a computer program. Students had the freedom to adjust five different slider bars, each representing a unique component of the music or movement. The basic qualities were rate, step size and direction. For the melody, these parameters controlled notes per minute, frequency of notes and the rise and fall of pitch; for the animation, they determined how fast and high the ball bounced and the tilt of the ball (“looking” up or down). To spice things up, researchers created two additional factors: jitter allowed students to inject unpredictability into their creation, while smoothness added “spikiness” to the rhythm of the bouncing ball or dissonance to the melody.

After ample time to familiarize themselves with the program, the students fiddled patiently with the bars until they found the perfect representation for five emotions: angry, happy, peaceful, sad, and scared. Incredibly, regardless of which particular emotion represented, both music and movement groups moved the bars into essentially the same general scheme. That is, while the absolute position of the bars differed between groups for each emotion, positions representing “angry” in music was always more similar to those of “angry” in movement, as compared to bars representing “happy”. Remember, the students were free to construct their interpretation of something as abstract as emotion, using two different brain modules – yet the result was highly similar! These data tease us with a tantalizing idea, that music and movement tickles our brain in comparable ways.

If this phenomenon relied on innate brain organization, it should apply to everyone, regardless of cultural influence. Yet music and dance often blossom from a strong cultural foundation, entwined with traditional rituals and ceremonies. Would these results survive across cultures?

In search of an answer, researchers took their experiment to L’ak, a rural village in a sparsely populated province in northeastern Cambodia. Isolated from global influence until the 1990s, the Kreungs, an ethic group in L’ak, boasts a vibrant tribal culture of music and dance. Although unable to completely escape from partial modernization, the Kreungs nevertheless remained relatively na?ve to western culture. The difference in musical expression is especially vast. The Kruengs have no concept of tuning, timbre, scale or any standardization that lies at the heart of western music. Their instruments, such as the single-stringed mem, also generate a different repertoire of sounds – instead of single clear-cut notes, the mem produces sounds similar to that of buzzing insects.

As most Kruengs are text- and computer- illiterate, researcher made several small adjustments to make the task easier: instead of word labels, they used pictures as prompt; they also swapped the computer mouse with real sliders. However, due to the infinite ways to place these sliders, many villagers froze in indecision. To make the task easier, researchers decided to limit each slider to three positions – “low”, “medium” and “high”.

The results were staggering. Despite enormous cultural differences, the villagers positioned the sliders for “happy”, “sad” and “scared” in more or less the same way as the college students, for both music and animation creations. When researchers grouped data for music and movement together, representations of all but one emotion matched. The one outlier was (surprisingly) “angry”, which was more similar to the “scared” prototype constructed with US data. Nevertheless, the two negative emotions still shared individual characteristics, such as fast and downward-directed.

Thus, music and movement share a common structure that the brain processes to express emotions in a similar way. This dynamic coupling seems to be universal, at least for most of the emotions tested, inviting speculations of an evolutionary origin. Perhaps humans first learned to extract emotion through movement (Grok raised his fist – he’s angry); the same areas that process emotionally-relevant changes in rhythm and speed were later recycled for detecting changes in sound, speech, and finally music. Thus, the brain creates a music-movement-emotion triad that is fundamentally inseparable due to their shared neural circuits.

Some evidence supports this nascent theory. Think about the many times you unconsciously bobbed your head, tapped your fingers or matched your steps to a tune. When we groove to the beat, our auditory and motor brain areas synchronize to produce a type of propagating brain wave called beta-oscillations, which parallels an intense feeling of enjoyment.

Ask any exhausted runner who runs with music blasting in their ears – what’s more motivating than matching your footsteps to a perfectly spaced power-up song?

Gymmin’ & Jammn’

For millennia, people have harnessed musical pleasure to push through strenuous or repetitive labor. Prisoners sang as they chipped stones in quarries; farmers whistled as they harvested the fields; women hummed as they scrubbed dirty clothes by the village stream. These days, music is played in fitness studios, often to give clients that extra psychological “pump”.

Why can music help us push through strenuous exercise?

Some scientists believe the effect occurs passively. As mentioned above, music – especially pieces with personal meaning – enhances physical and emotional arousal, it gets the heart pumpin’, sweat pourin’ and dopamine flowin’. Studies in psychology show that music boosts self-esteem and confidence, putting you in “bear mode”. Workout tunes may also act as a distraction, diverting uncomfortable physical sensation to various features in the music instead. Remarkably, contrary to popular belief, slow-paced music may be just as effective, though the data is somewhat controversial.

Others believe that it is our dynamic interaction with music that dampens feelings of tiredness. With music blasting in our ears, we automatically couple physical movements – running, rowing, climbing – to the beat in a subconscious attempt to synchronize pace, tempo and rhythm. Here, we are not passively receiving the benefit of music. Instead, grooving to the tune, we perceive ourselves as “making” music. This in turn generates a sense of pleasure so profound that it transcends sensory modules, damping the feelings of exertion and pain that inevitably accompanies strenuous exercise.

A recent study tried to tease the two hypotheses apart with a rather quirky method dubbed “jymmin”, a mix of “gymmin” and “jammin”. The researchers rigged up three common exercise machines – a tower, a stepper and an ab trainer – to music composition software so that the movements of the machines could create sounds that interactively combined into a musical piece. When using the machines, a person would thus perceive the emerging music as a result of his or her muscle contractions.

Researchers recruited 61 volunteers to try out these peculiar machines. The volunteers were neither professional athletes nor musicians, though some had previous musical training. In groups of three, volunteers picked their favorite machine and worked out in several sessions, each lasting 6 min. In one session, they passively listened to music; in another, they actively made music together. The volunteers were allowed to workout at their chosen pace; after each session, they filled out a questionnaire indicating their perceived physical effort. As they exercised, researchers constantly monitored the force of muscle contraction and the amount of oxygen consumed as objective measures of effort.

For 53 out of the 61 volunteers, their perceived level of physical exertion was lower when they were making the tunes, as opposed to passively listening to a similar musical composition. The pattern of movement also changed: when passively gymmin’, volunteers moved in a highly repetitive manner; when jymmin’, they moved more erratically, often holding the weights for longer periods of time. Although the total force applied to the machine did not differ between the groups, volunteers showed lower oxygen consumption (hence less metabolic effort) in the music-making session. The researchers thus concluded that the act of making music increased the metabolic efficacy of working out; less physiological effort in turn means less perceived exertion.

While certainly an innovative study, several issues linger. When jymmin’, participants naturally settled into an unusual (and unsafe) weight-lifting rhythm, more reflective of the bodily movements of a jazz musician than an athlete. In this sense it’s hard to say how much these results translate into a real-world, structured exercise setting. Since volunteers always worked out in groups of three, it’s also highly possible that social expectations were at play; would you stop if your “bandmates” continued jymmim’ on? Finally, our normal workouts don’t actually utilize music-making instruments; could we really experience an illusion of making music as we move to the beat?

Science is only starting to uncover the ancient marriage between music, movement and mood. It’s a tough area of research, fraught with messy data and difficult interpretations. Yet all this emerging evidence is painting the beginnings of a beautiful picture: at one point during eons of evolution, our brain gained the ability to appraise and deeply value rhythmic strings of notes; hence forth, our emotions and movements became forever entwined with music.

In the past, our ancestors may have used the power of music in rituals to promote bonding within communities. In the future, as we increase our understanding in the evolution and neuroscience of music, its psychological powers may potentially be harnessed as therapy for those with behavioural and psychiatric disorders. Such research is under way.

References:

Sievers B et al. 2013. Music and movement share a dynamic structure that supports universal expressions of emotion. PNAS, 110 (1):70-75

Salimpoor VN et al. 2011. Anatomically distinct dopamine release during anticipation and experience of peak emotion to music. Nature Neuroscience, 14: 257-262

Salimpoor VN et al. 2013. Interactions Between the Nucleus Accumbens and Auditory Cortices Predict Music Reward Value. Science, 340 (6129): 216-219

Fritz TH et al 2013. Musical agency reduces perceived exertion during strenuous physical performance. PNAS, doi:10.1073/pnas.1217252110