Synchronized Drumming Enhances Activity in the Caudate and Facilitates Prosocial Commitment - If the Rhythm Comes Easily

Abstract

Why does chanting, drumming or dancing together make people feel united? Here we investigate the neural mechanisms underlying interpersonal synchrony and its subsequent effects on prosocial behavior among synchronized individuals. We hypothesized that areas of the brain associated with the processing of reward would be active when individuals experience synchrony during drumming, and that these reward signals would increase prosocial behavior toward this synchronous drum partner. 18 female non-musicians were scanned with functional magnetic resonance imaging while they drummed a rhythm, in alternating blocks, with two different experimenters: one drumming in-synchrony and the other out-of-synchrony relative to the participant. In the last scanning part, which served as the experimental manipulation for the following prosocial behavioral test, one of the experimenters drummed with one half of the participants in-synchrony and with the other out-of-synchrony. After scanning, this experimenter “accidentally” dropped eight pencils, and the number of pencils collected by the participants was used as a measure of prosocial commitment. Results revealed that participants who mastered the novel rhythm easily before scanning showed increased activity in the caudate during synchronous drumming. The same area also responded to monetary reward in a localizer task with the same participants. The activity in the caudate during experiencing synchronous drumming also predicted the number of pencils the participants later collected to help the synchronous experimenter of the manipulation run. In addition, participants collected more pencils to help the experimenter when she had drummed in-synchrony than out-of-synchrony during the manipulation run. By showing an overlap in activated areas during synchronized drumming and monetary reward, our findings suggest that interpersonal synchrony is related to the brain's reward system.

Rhythm in joint action: psychological and neurophysiological mechanisms for real-time interpersonal coordination

“…Inverse models represent transformations from intended action outcomes to the motor commands that produce them. It has been argued that rhythmic interpersonal coordination relies on separate forward and inverse models to simulate one's own and others' actions slightly in advance of their production [11,41,51,52]. On this account, the coupling of 'own' and 'other' internal models in a 'joint' internal model facilitates fluent interpersonal coordination by allowing potential errors in timing to be anticipated and corrected before they occur [41].…”

“…An fMRI study suggested that the influence of synchrony on prosociality relates to caudate activation in the brain's reward system [51]. Reward signals are mediated by release of dopamine and opioids [159], thus neurochemistry could influence the synchrony-affiliation links [160].…”

Cognitive mechanisms for responding to mimicry from others

“…Kokal et al (2011) examined activity in the caudate during a drumming task in which participants experienced a partner drumming in synchrony or asynchrony with them. They found that that ease of drumming was associated with activation in the caudate, a region also active in processing monetary reward.…”

“…There also appear to be shared brain systems in responding to mimicry versus synchronised movement (Kokal et al, 2011;van Baaren et al, 2004;Wiltermuth & Heath, 2009). By definition, mimicry involves movements which match in form, whereas synchrony involves movements which match in time.…”

“…Only one study has measured a mimickee's neural response to mimicry of their postures and body movements (Hogeveen, Chartrand, & Obhi, 2014). However, several other research groups have measured neural activation in response to closely related experiences, including being overtly imitated by a live experimenter or a video stimulus Decety, Chaminade, Grèzes, & Meltzoff, 2002;Guionnet et al, 2012), passively observing a mimicry interaction from the perspective of the mimickee (Kühn et al, 2010), and interactional synchrony driven by another person (Cacioppo et al, 2014;Kokal, Engel, Kirschner, & Keysers, 2011). Here we consider the available data from these different paradigms in order to infer possible neural systems involved in responding to mimicry.…”