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Abstract:
Background and aims
Music making in groups is a key example of dynamic cooperative behavior and, more fundamentally, a form of sensorimotor coupling. As a novel approach to explore neural correlates of dynamic cooperation and leader-follower relationships, we present a functional MRI (FMRI) study of sensorimotor synchronization (SMS) finger tapping with an adaptive “virtual partner”.
Methods
Sixteen healthy, right handed individuals with paced finger tapping experience participated in two FMRI experiments. In experiment 1, subjects tapped in synchrony with a “virtual partner” programmed to maintain the overall pulse (leader) while still adapting its timing to reduce asynchronies between human taps and computer tones. The degree to which the virtual partner adapted the pacing signal was varied across five conditions of phase correction (ranging from non-adaptive to completely adaptive). In experiment 2, the “virtual partner” adapted both with phase and five levels of period correction (follower) forcing the human partner to lead and maintain the overall pulse. Following each task block, subjective ratings of “influence over the pulse” and “difficulty” were acquired.
Results
Behavioural tapping data replicate findings from previous SMS studies. Imaging data from both experiments reveal activation of the anterior insula during conditions where the human participant had more influence over the pulse. TPJ activity is observed in a contrast of overly adaptive (“unhelpful”) vs. partially adaptive (“helpful”) cooperation in experiment 1 and in a contrast of complete vs. no period correction in experiment 2. ROI analyses further characterize this activation and correlations with subjective ratings substantiate our theory that identified activation is related generally to social interaction/cooperation and more specifically to an increased sense of agency.
Conclusions
This adaptively-paced tapping task represents a model with which to study the dynamic, cooperative relationship experienced when playing music in a group as well as shared or specific neural activation within contexts where the human participant either followed or led in the synchronizing partnership. In particular, we report activation of areas implicated in cooperation and agency during conditions in which the human participant had most influence over the pulse and when the virtual partner’s adaptive nature impedes synchronisation thus perturbing the subject's sense of agency.
