At the famous carnival parades in Rio de Janeiro, thousands of people let themselves be infected by the samba rhythms and feel encouraged to dance and celebrate exuberantly. Neuroscientists have now investigated what might be behind this sweeping effect of samba. Brain scans show: Samba music activates brain areas in which rhythm and movement are processed and which are involved in predictions. Important here is the synchronicity with which the musicians play together. If the researchers manipulated the samba recordings in such a way that the percussion was slightly shifted, the music had a much weaker effect. The researchers assume that the observations can also be transferred to other styles of music.
Hundreds of percussionists provide intoxicating rhythms at the carnival in Rio de Janeiro, which send dancers, singers and spectators to the parades into ecstasy. When in high spirits, people experience a strong sense of connection with others and feel the urge to move and dance to the rhythms. In addition to the music, the overall atmosphere in Rio with colorful costumes and partying people undoubtedly plays a role. But even in a laboratory setting, the rhythm of the drums alone can provide the impulse to move to the music.
Samba music in the laboratory
A team led by Annerose Engel from the D’OR Institute for Research and Education in Rio de Janeiro has now investigated what this strong effect of samba music is based on. In cooperation with a recognized master of a samba drum unit in Rio de Janeiro, the researchers created a typical piece of music with nine typical percussion instruments. They then manipulated the interplay of the instrument groups by slightly delaying the snare drums, which set a steady pulse, in relation to the other instruments.
In the first part of the study, twelve subjects heard these recordings – sometimes the original version, sometimes manipulated versions with a shift of 28, 55 or 83 milliseconds. The music was played loud (85 decibels) or very loud (95 decibels). For each recording, they rated how enjoyable they found the music and how strong their “groove feeling” was, that is, the urge to move to it. All subjects were musical themselves and said they liked samba.
Synchronicity encourages dancing
The result: the test persons perceived the original recording, in which the musicians played synchronously, as particularly pleasant and stimulating. In particular, when the music was played very loudly, the subjects felt a clear urge to move to it. However, this only applied if the instruments were playing synchronously. If the snare drum deviated from the common rhythm by just a few milliseconds, the music produced less of a groove feeling. The effect was stronger the better the subject’s sense of rhythm. The researchers had previously collected this using a standardized test.
In addition to the behavioral study, Engel and her colleagues conducted a neurological study in a group of 21 new subjects. These study participants also had previous musical experience. These subjects listened to the Samba recordings while an MRI scanner recorded their brain activity. It turned out that the more synchronously the instruments sounded, the more active was a network in their brain that is responsible for movements and the perception of rhythms: the supplementary motor area, the left premotor cortex and the left frontal gyrus. These brain regions not only come into action during movements, but also when something is to be predicted – a fundamental process of our perception.
groove in the brain
“The activity in the network of these motor-associated regions could be the neuronal basis for the feeling of groove, in particular the pronounced urge to move,” explains Engel. “The more synchronously the instruments play together, the clearer the underlying beat can be captured. This probably simplifies the prediction processes.” The researchers also found a neuronal correlate for the feeling of intense emotions and social connectedness that some participants described when listening to the music: these participants showed increased activity in the subgenual cingulate cortex when the synchronous rhythms were heard – a brain region that processes social bonding, prosocial behavior, and group identification.
The researchers assume that the observations can also be transferred to other styles of music such as jazz or electronic music, as well as to ritual drum music from other cultures. The better the interplay between the instruments, the clearer the pulse – and the stronger the sense of groove that is created. “These findings could also help us in neurorehabilitation,” says Engel. Music therapy is used, among other things, in stroke patients in order to use rhythmic stimulation to train cognitive abilities such as attention and to practice movement sequences again. “Music that promotes a groove experience could be particularly suitable for this,” says Engel.
Source: Max Planck Institute for Human Cognitive and Brain Sciences, Article: Annerose Engel (D’OR Institute for Research and Education, Rio de Janeiro, Brazil) et al., Frontiers in Neuroscience, doi: 10.3389/fnins.2022.779964