Playing music in ensemble requires enhanced sensorimotor coordination and the non-verbal communication of musicians that need to coordinate their actions precisely with those of others. As shown in our previous studies on guitar duets, and also on a guitar quartet, intra- and inter-brain synchronization plays an essential role during such interaction. At the same time, sensorimotor coordination as an essential part of this interaction requires being in sync with the auditory signals coming from the played instruments. In this study, using acoustic recordings of guitar playing and electroencephalographic (EEG) recordings of brain activity from guitarists playing in duet, we aimed to explore whether the musicians' brain activity synchronized with instrument sounds produced during guitar playing. To do so, we established an analytical method based on phase synchronization between time-frequency transformed guitar signals and raw EEG signals. Given phase synchronization, or coupling between guitar and brain signals, we constructed so-called extended hyper-brain networks comprising all possible interactions between two guitars and two brains. Applying a graph-theoretical approach to these networks assessed across time, we present dynamic changes of coupling strengths or dynamic orchestration of brains and instruments during free guitar improvisation for the first time. We also show that these dynamic network topology changes are oscillatory in nature and are characterized by specific spectral peaks, indicating the temporal structure in the synchronization patterns between guitars and brains. Moreover, extended hyper-brain networks exhibit specific modular organization varying in time, and binding each time, different parts of the network into the modules, which were mostly heterogeneous (i.e., comprising signals from different instruments and brains or parts of them). This suggests that the method capturing synchronization between instruments and brains when playing music provides crucial information about the underlying mechanisms. We conclude that this method may be an indispensable tool in the investigation of social interaction, music therapy, and rehabilitation dynamics.

中文翻译：

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免费吉他即兴演奏期间大脑和乐器的动态编排。

在合奏中播放音乐需要增强感觉运动协调性，以及需要与其他人精确协调其行为的音乐家的非语言交流。如我们先前关于吉他二重奏和吉他四重奏的研究所示，在这种交互过程中，大脑内部和大脑之间的同步起着至关重要的作用。同时，感觉运动协调作为这种相互作用的重要部分，需要与来自演奏乐器的听觉信号同步。在这项研究中，我们使用吉他演奏的声音记录和吉他演奏者在二重奏中进行的脑活动的脑电图（EEG）记录，我们旨在探讨音乐家的大脑活动是否与吉他演奏过程中产生的乐器声音同步。为此，我们建立了一种基于时频变换的吉它信号和原始EEG信号之间的相位同步的分析方法。给定相位同步或吉他与大脑信号之间的耦合，我们构建了所谓的扩展超大脑网络，该网络包括两个吉他和两个大脑之间的所有可能的相互作用。将图论方法应用于跨时间评估的这些网络，我们首次展示了免费吉他即兴演奏期间耦合强度的动态变化或大脑和乐器的动态编排。我们还表明，这些动态网络拓扑结构的变化本质上是振荡的，并且具有特定的频谱峰值，表明吉他和大脑之间的同步模式具有时间结构。此外，扩展的超脑网络表现出随时间变化的特定模块化组织，并且每次都将网络的不同部分绑定到模块中，这些模块大部分是异构的（即，包含来自不同仪器和大脑或其中一部分的信号）。这表明在演奏音乐时捕获乐器和大脑之间的同步的方法可提供有关潜在机制的关键信息。我们得出的结论是，这种方法可能是社交互动，音乐疗法和康复动力学研究中必不可少的工具。这表明在演奏音乐时捕获乐器和大脑之间的同步的方法可提供有关潜在机制的关键信息。我们得出的结论是，这种方法可能是社交互动，音乐疗法和康复动力学研究中必不可少的工具。这表明在演奏音乐时捕获乐器和大脑之间的同步的方法可提供有关潜在机制的关键信息。我们得出的结论是，这种方法可能是社交互动，音乐疗法和康复动力学研究中必不可少的工具。