It's been a while (almost 5 years) since I've participating in any sort of writing contest. I applied to the Access to Understanding contest where you have to summarise (abstract out) a scientific article. Curiously, the winning entry did the same article as I did :-)
I did not quite make the shortlist this time... I hope I'm not losing my magic touch! Anyway, here's my take:
Beat it!
I dare you to start listening to “Michael Jackson’s” song “Beat it” and resist its rhythm. Don’t tap your foot. Don’t drum your fingers. Don’t nod your head. It is hard to help it, and even if the beat does not invade your body, it still assails your mind. Our urge drives us to follow the rhythm, something we do effortlessly, almost unconsciously.
We cannot say that this capacity is uniquely human, as anyone surfing YouTube for “dancing parrots” can attest. However, it seems to be fairly rare in the animal kingdom. Clearly, being able to hear the beat helps when we are listening to music and let us to move in synchrony to music, maybe even dance. Importantly, our capacity to perceive and produce a predictable beat might even form the foundations of language itself, structuring the words we hear and the way we speak.
But how does our brain process the beat? Some very ancient brain structures appear to be key to beat perception. These are the basal ganglia, a conglomerate of deep brain structures that is located, you guessed it, at the base of the brain.
The putamen (pronounced pyu-tah-men) is a round subpart of the basal ganglia. It is named after its shape, Latin for the shell or husk of a fruit kernel. Previous studies have shown that this region becomes more active when people are listening to predictable beat sequences than non-beat sequences. However, what is unclear is whether the putamen is involved in finding the beat in the song, or in predicting how the beat will continue once it has been found.
Investigator, musician and TED speaker Jessica Grahn decided to answer this question together with James Rowe. To do so, they used functional Magnetic Resonance Imaging (fMRI). This technique looks at how blood flow increases or decreases as brain regions that become more or less active. People of various musical backgrounds lay in the MRI scanner while listening to different beats. They heard sequences of sounds with either a predictable beat at different speeds, or similar sequences but without a predictable beat. Occasionally, after hearing a sequence, they had to press a button to say how well they could hear the beat.
Grahn and Rowe expected that the putamen predicts a sequence once the beat has been found. If so, the putamen should be more active when the next sequence is either the same, or at least has a similar speed, since the beat prediction does not change. If instead the putamen helps us find the beat, we should expect the opposite. It should become more active when the beat changes speed, as it would have to search again for the correct rhythm.
They found that people could easily distinguish beat and non-beat sequences. The participants clearly felt the beat, even when the speed of the sequences changed. Also, they found that the putamen was more responsive to beat sequences than non-beat sequences. Other brain areas were also activated by beat sequences, such as the supplementary motor area and left premotor cortex. These brain regions often act in concert with the basal ganglia, perhaps forming a conscious movement or body-based representation of the beat.
Non-beat sequences instead activated regions involved in precise timing, like cerebellum, and areas that are involved in difficult mental tasks, like parietal and inferior frontal cortex. These results were in line with Grahn's previous findings.
Critically, they also saw that the putamen was more active when the previous sequence was of a similar speed, compared to when it was faster or slower. This confirmed their suspicion that the putamen was engaged in predicting the beat, rather than finding it.
Curiously, they found that the putamen was similarly active in the first and second half of the experiment. Even though the sound sequences became more and more familiar, this did not change how the putamen reacted to them. Also, their findings were not related to musical expertise. Musical experts with more than 6 years of musical schooling did not engage the putamen any more or less than people with little or no training.
Why does this research matter, you might ask. If understanding our capacity to hear music is not enough, you should know that such research is key to understanding complex motor diseases. For instance, Parkinson’s disease affects the same beat-sensitive structures, the basal ganglia. Besides being unable to move fluidly, patients with Parkinson's also find it difficult to distinguish between different beats. But crucially, rhythm can have healing power. The power of the beat can restore movement to Parkinson's patients, who break free from their motionlessness when they hear music. If we are to beat the odds of brain disease, we'll need all help we can get.
