Multi-brain network, also known as social cooperative network, is formed by multiple animal or human brains, whose changes of functional connectivity in the intra- and inter-brain during construction are unclear at present. To investigate the intra- and inter-brain functional connectivity of pigeons while performing a social cooperation task, we designed an inter-brain synchronization task to train three pigeons to synchronize their neural activities using cross-brain neurofeedback. Then the neural signals of three pigeons were simultaneously recorded by using a hyperscanning approach, and inter-brain synchronization was calculated using the phase-locked value (PLV) online. Finally, the intra- and inter-brain functional connectivity of three pigeons were analyzed. We found that during long-term neurofeedback training, with the increase of the inter-brain synchronization of three pigeons, the intra- and inter-brain functional connectivity also enhance significantly. Moreover, we also found that the above phenomenon relies on the external visual cue. These results suggest that the promotion of social cooperation is the result of the modulation between the intra- and inter-brain, which may be an underlying neural mechanism of the communication and cooperation among individuals in social networks.

多脑网络，又称社会合作网络，是由多个动物或人脑组成，其在构建过程中脑内和脑间功能连接的变化目前尚不清楚。为了研究鸽子在执行社会合作任务时的脑内和脑间功能连通性，我们设计了一个脑间同步任务来训练三只鸽子使用跨脑神经反馈同步它们的神经活动。然后使用超扫描方法同时记录三只鸽子的神经信号，并使用锁相值（PLV）在线计算脑间同步。最后，分析了三只鸽子的脑内和脑间功能连接。我们发现，在长期的神经反馈训练中，随着三只鸽子脑间同步性的增加，脑内和脑间的功能连接也显着增强。此外，我们还发现上述现象依赖于外部视觉线索。这些结果表明，社会合作的促进是大脑内和大脑间调节的结果，这可能是社会网络中个体之间交流与合作的潜在神经机制。