Dynamic Orchestration of Brains and Instruments During Free Guitar Improvisation.

Viktor Müller,Ulman Lindenberger

doi:10.3389/fnint.2019.00050

Abstract

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.

Highlights

We describe different situations of connections between guitars and brains here, which together exhibit complex networks with network topology changing in time and reflecting the dynamic orchestration of brains and instruments in guitar duos
The main findings are that such extended hyper-brain networks when playing guitar in duet (1) exhibit different temporal dynamic changes of network strengths, which are oscillatory in nature and have specific temporal structure for different EEG and instrument frequency components, and (2) feature different connectivity and community structures combining different brain regions and frequency components of instrument sounds, which share different, mostly heterogeneous modules
It should be noted that the instrument’s sound is a result of the musician’s behavior, which is based on sensorimotor synchronization and action

Summary

Introduction

As noted by D’Ausilio et al (2015): “Group-level musical coordination can be considered as a microcosm of social interaction.” A recently emerging view in music neuroscience with regard to hyperscanning methods holds that playing music in groups is social and interactive (Keller et al, 2014; Acquadro et al, 2016; Chang et al, 2017), but that it requires strong inter-brain synchronization and specific hyper-brain network activity supporting interpersonal action coordination (Lindenberger et al, 2009; Sänger et al, 2011, 2012, 2013; Müller et al, 2013, 2018b). A recently emerging view in music neuroscience with regard to hyperscanning methods holds that playing music in groups is social and interactive (Keller et al, 2014; Acquadro et al, 2016; Chang et al, 2017), but that it requires strong inter-brain synchronization and specific hyper-brain network activity supporting interpersonal action coordination (Lindenberger et al, 2009; Sänger et al, 2011, 2012, 2013; Müller et al, 2013, 2018b). Little, if anything, is known about the interaction between brain processes or mechanisms implementing interpersonally coordinated behavior when playing music and the instruments used for music production

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Conclusion