| Background: Interpersonal movement coordination is an indispensable and important aspect of daily life.Behavioral studies on intrapersonal and interpersonal have found that the difficulty of periodic bimanual coordination movements is mainly influenced by two factors: one is the spatiotemporal complexity of body movements(e.g.,symmetric mode,alternating mode),and the other is the frequency of movements.Complex interactions also exist between these two factors.Therefore,when movement coordination involves two divided nervous systems,which neural activities are involved in the low-level control factors(frequency)and high-level control factors(temporal and spatial characteristics/symmetry,alternation),and which brain regions do they correspond to when they interact? The answer to these questions may show some obvious differences from the coordination movement of intrapersonal controlled by a single nervous system.Some of functional imaging studies have found that the bimanual coordination of individuals under different movement modes(symmetrical,alternating)is closely related to the activity of the supplementary motor area(SMA).When it comes to interpersonal movement coordination,the unique characteristics of linking two independent nervous systems by means of vision makes the activity of the mirror nervous system a key mechanism for interpersonal movement coordination.Methods: In this study,a modified experimental paradigm of interpersonal bimanual coordination was adopted.16 pairs of participants were given symmetrical mode and alternating mode of interpersonal movement coordination tasks at 6 frequencies,and functional near infrared spectroscopy imaging(fNIRS)with a sampling rate of 7.81 Hz was used to monitor the hemodynamic indicators of individuals when they completed different conditional coordination tasks.Results:Firstly,at the behavioral level,the PLV of the symmetric mode was significantly greater than that of the alternate mode at each frequency,indicating that the subjects’ actions in the symmetric mode are more stable than in the alternate mode.In addition,we also found that the PLV at the frequency of 2.7Hz and 3.3Hz was significantly greater than that at the other 5 frequencies for the subjects in the alternate mode.Secondly,Our most important finding was that comparing to alternate mode,the mean [Hb O] of the symmetric mode in the premotor cortex was significantly greater than that in the alternate mode at frequencies of 2.4Hz,2.7Hz and3.3Hz.At the same time,fNIRS data showed the movement in the alternate mode,the mean [Hb O] of ROI-3 at the frequency of 2.4Hz was significantly less than that at1.8Hz and 2.1Hz,and that the mean [Hb O] at the frequency of 2.7Hz and3.0Hz was also significantly less than that at 1.8Hz,while in the symmetric mode,no significant difference was found between different frequencies.And then,for the synchronization between the two brains,the IBS was analyzed by 2(phase)×6(frequency)repeated measurement variance analysis and found that the main effect of the frequency of ROI-1 was significant and at 2.7Hz was significantly lower than other frequencies.Finally,the correlation analysis between nerve and behavior: For ROI-1,IBS and PLV are both negatively correlated,not reaching significant levels,and for [Hb O] of ROI-3,Field-dependent individuals are positively correlated with individual activations in symmetrical and alternating modes,while Field-independent individuals and the activation in each action mode is negatively correlated,none of them reaches a significant level.Conclusion: Interpersonal bimanual coordination involves activity in the premotor areas(premotor cortex,SMA,and frontal eye fields).More oxygen is consumed in these regions in alternating mode as compared to symmetric mode.These regions are also related to the phase transition from alternating mode to symmetric mode at higher frequencies.Otherwise,the inferior parietal lobe also plays an important role in the interpersonal bimanual coordination. |
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