From babies to adults with no musical training, everyone can tap and move to a beat – whether nodding in time to a symphony, bopping to jazz, or dancing it Gangnam Style. That skill relies on a combination of basic motor processes and higher order cognitive processes, according to a new study. The research could eventually help develop musical rehabilitation techniques for stroke patients or those with Parkinson’s disease.
The ability to find and tap to a musical beat is a complex process and one increasingly under study. “Beat finding is a fascinating phenomenon because it is a spontaneous and perhaps uniquely, human ability,” says Virginia Penhune of Concordia University, a co-author on the new study. “And a strong musical beat can facilitate motor response in people with Parkinson’s disease and stroke,” making it a research-rich field of study.
In the new study, the researchers, led by Shu-Jen Kung of National Yang-Ming University in Taiwan, sought to understand not only the neural processes underlying how people move to a beat but also how they find the beat in the first place. A unique aspect of the study involved using an fMRI scanner while controlling for the background noise present in the scanner. Scanner noise, which is quite loud and rhythmic, has posed a challenge in the past for studies on musical beat.
The participants, all trained musicians, listened to a number of different rhythms that changed continuously throughout the experiment, ranging from metrically simple to very complex. To control for the scanner noise, the researchers played the rhythms in silence and then acquired the MRI data in short bursts following the stimuli. “We also went one step further and made sure that the onset of the scanner noise was precisely timed to the beat of the rhythms,” Penhune says, “so that if people were attending to the noise, even sub-consciously, it would fit with the predicted beat rather than fighting it.”
As reported in the Journal of Cognitive Neuroscience, finding and tapping to the beat recruited overlapping brain regions, including the superior temporal gyrus (STG), premotor cortex, and ventrolateral pre-frontal cortex (VLPFC). The activity in the STG and VLPFC appeared to be important for retrieving, selecting, and maintaining the musical beat. The results differ past work that identified the basal ganglia – a key component of the motor system – to be consistently engaged in musical beat perception. “We did not find such a strong contribution of this region and we are currently engaged in developing new experiments to understand the differential contributions of the basal ganglia and the cortical regions we found to be important in our experiment,” Penhune says.
One of the significant implications for the work is for rehabilitation from stroke and in Parkinson’s disease. Research has found that music with a strong beat or an auditory metronome can improve gait and other aspects of movement in such patients. “However, we do not really know how this might occur,” Penhune says. “A better understanding of how the brain processes musical beat could allow us to better use its effects in rehabilitation.” This line of work is something another co-author, Dr. Joyce Chen, is pursuing in her work at the Centre for Stroke Recovery at the University of Toronto.
The research team is pursuing several follow-up studies, including developing a shorter version of the experiment to test non-musicians and comparing musical and motor abilities in trained dancers versus musicians. They are also starting to look at rhythm and beat perception and production in different types of musicians, including singers and percussionists. “Singers often have a bad reputation in terms of rhythm, while drummers are obviously experts,” Penhune says. “We want to see how the groups compare on basic tasks, and when we ask them to respond either by singing or tapping.”
-Lisa M.P. Munoz
The paper “Interacting Cortical and Basal Ganglia Networks Underlying Finding and Tapping to the Musical Beat,” Shu-Jen Kung, Joyce L. Chen, Robert J. Zatorre, and Virginia B. Penhune, was published online on Nov. 19, 2012 in the Journal of Cognitive Neuroscience.
Media contact: Lisa M.P. Munoz, CNS Public Information Officer,