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Brains swinging in concert: cortical phase synchronization while playing guitar.

Lindenberger U, Li SC, Gruber W, Müller V - BMC Neurosci (2009)

Bottom Line: By applying synchronization algorithms to intra- and interbrain analyses, we found that phase synchronization both within and between brains increased significantly during the periods of (i) preparatory metronome tempo setting and (ii) coordinated play onset.Presumably, these couplings reflect similarities in the temporal properties of the individuals' percepts and actions.Whether between-brain oscillatory couplings play a causal role in initiating and maintaining interpersonal action coordination needs to be clarified by further research.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Lifespan Psychology, Max Planck Institute for Human Development, Lentzeallee 94, 14195 Berlin, Germany. lindenberger@mpib-berlin.mpg.de

ABSTRACT

Background: Brains interact with the world through actions that are implemented by sensory and motor processes. A substantial part of these interactions consists in synchronized goal-directed actions involving two or more individuals. Hyperscanning techniques for assessing fMRI simultaneously from two individuals have been developed. However, EEG recordings that permit the assessment of synchronized neuronal activities at much higher levels of temporal resolution have not yet been simultaneously assessed in multiple individuals and analyzed in the time-frequency domain. In this study, we simultaneously recorded EEG from the brains of each of eight pairs of guitarists playing a short melody together to explore the extent and the functional significance of synchronized cortical activity in the course of interpersonally coordinated actions.

Results: By applying synchronization algorithms to intra- and interbrain analyses, we found that phase synchronization both within and between brains increased significantly during the periods of (i) preparatory metronome tempo setting and (ii) coordinated play onset. Phase alignment extracted from within-brain dynamics was related to behavioral play onset asynchrony between guitarists.

Conclusion: Our findings show that interpersonally coordinated actions are preceded and accompanied by between-brain oscillatory couplings. Presumably, these couplings reflect similarities in the temporal properties of the individuals' percepts and actions. Whether between-brain oscillatory couplings play a causal role in initiating and maintaining interpersonal action coordination needs to be clarified by further research.

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Phase synchronization within and between brains during the preparatory period of metronome tempo setting. (A) Topological distributions of PLI in a representative pair of guitarists, A and B, at the theta frequency (4.95 Hz) 140 ms after stimulus-onset (second metronome beat). Fronto-central maxima of PLI are shown. (B) Time-frequency diagrams of average PLI for guitarist A and B separately. PLI was averaged across six fronto-central electrodes. Only significant PLI-values (p < 0.01) are highlighted. Time zero is time locked to the second metronome beat. Metronome beats are shown by white arrows. The time course of PLI values at the theta frequency (4.95 Hz) is depicted below the time-frequency diagram. (C) Interbrain synchronization between the two guitarists measured by IPC at the theta frequency (4.95 Hz) 140 ms after stimulus onset. Colored lines indicate synchrony between electrode pairs of the two guitarists, corresponding to significant interbrain synchronization. Only IPC values higher than 0.41 are highlighted. (D) Time-frequency diagram of the average IPC averaged across six electrode pairs. In the left diagram (A -> B), the selected electrode pairs represent phase coherence between one electrode of guitarist A (Cz) to the six fronto-central electrodes of guitarist B. Conversely, the right diagram (B -> A) refers to one electrode of guitarist B and the six fronto-central electrodes of guitarist A. Only significant IPC-values (p < 0.01) are highlighted. The time course of IPC values at the theta frequency (4.95 Hz) is depicted below the time-frequency diagram. SL = significance level.
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Figure 1: Phase synchronization within and between brains during the preparatory period of metronome tempo setting. (A) Topological distributions of PLI in a representative pair of guitarists, A and B, at the theta frequency (4.95 Hz) 140 ms after stimulus-onset (second metronome beat). Fronto-central maxima of PLI are shown. (B) Time-frequency diagrams of average PLI for guitarist A and B separately. PLI was averaged across six fronto-central electrodes. Only significant PLI-values (p < 0.01) are highlighted. Time zero is time locked to the second metronome beat. Metronome beats are shown by white arrows. The time course of PLI values at the theta frequency (4.95 Hz) is depicted below the time-frequency diagram. (C) Interbrain synchronization between the two guitarists measured by IPC at the theta frequency (4.95 Hz) 140 ms after stimulus onset. Colored lines indicate synchrony between electrode pairs of the two guitarists, corresponding to significant interbrain synchronization. Only IPC values higher than 0.41 are highlighted. (D) Time-frequency diagram of the average IPC averaged across six electrode pairs. In the left diagram (A -> B), the selected electrode pairs represent phase coherence between one electrode of guitarist A (Cz) to the six fronto-central electrodes of guitarist B. Conversely, the right diagram (B -> A) refers to one electrode of guitarist B and the six fronto-central electrodes of guitarist A. Only significant IPC-values (p < 0.01) are highlighted. The time course of IPC values at the theta frequency (4.95 Hz) is depicted below the time-frequency diagram. SL = significance level.

Mentions: Synchronization within the brains as measured by PLI during the preparatory period of metronome tempo setting was highest at fronto-central sites (Figure 1A). Averaged PLI values from the six fronto-central electrodes (F3, Fz, F4, C3, Cz, and C4) were calculated in the time-frequency domain for each frequency bin and time lag. Based on the averaged PLI, synchronization within the brains was particularly high in the frequency range between 2 and 10 Hz with the maximum in the theta frequency band (3–7 Hz). This effect was strictly related to the onset of the metronome beats (Figure 1B) and was found practically in all participants (Figure S1). As for synchronization between brains as measured by IPC, coherence was also strongest for fronto-central connections (Figure 1C). Averaged IPC values from the Cz electrode of guitarist A to the six fronto-central electrodes (F3, Fz, F4, C3, Cz, and C4) of guitarist B and vice visa were thus calculated. Based on the averaged IPC, between-brain synchronization was most clearly observable in the frequency range between 3 and 8 Hz, with the maximum being around 5 Hz (Figure 1D). Interbrain phase coherence tended to be stronger in the pairs of guitarists who also showed high synchronization within brains (i.e., pairs 3, 4, and 7 in Figure S1).


Brains swinging in concert: cortical phase synchronization while playing guitar.

Lindenberger U, Li SC, Gruber W, Müller V - BMC Neurosci (2009)

Phase synchronization within and between brains during the preparatory period of metronome tempo setting. (A) Topological distributions of PLI in a representative pair of guitarists, A and B, at the theta frequency (4.95 Hz) 140 ms after stimulus-onset (second metronome beat). Fronto-central maxima of PLI are shown. (B) Time-frequency diagrams of average PLI for guitarist A and B separately. PLI was averaged across six fronto-central electrodes. Only significant PLI-values (p < 0.01) are highlighted. Time zero is time locked to the second metronome beat. Metronome beats are shown by white arrows. The time course of PLI values at the theta frequency (4.95 Hz) is depicted below the time-frequency diagram. (C) Interbrain synchronization between the two guitarists measured by IPC at the theta frequency (4.95 Hz) 140 ms after stimulus onset. Colored lines indicate synchrony between electrode pairs of the two guitarists, corresponding to significant interbrain synchronization. Only IPC values higher than 0.41 are highlighted. (D) Time-frequency diagram of the average IPC averaged across six electrode pairs. In the left diagram (A -> B), the selected electrode pairs represent phase coherence between one electrode of guitarist A (Cz) to the six fronto-central electrodes of guitarist B. Conversely, the right diagram (B -> A) refers to one electrode of guitarist B and the six fronto-central electrodes of guitarist A. Only significant IPC-values (p < 0.01) are highlighted. The time course of IPC values at the theta frequency (4.95 Hz) is depicted below the time-frequency diagram. SL = significance level.
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Related In: Results  -  Collection

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Figure 1: Phase synchronization within and between brains during the preparatory period of metronome tempo setting. (A) Topological distributions of PLI in a representative pair of guitarists, A and B, at the theta frequency (4.95 Hz) 140 ms after stimulus-onset (second metronome beat). Fronto-central maxima of PLI are shown. (B) Time-frequency diagrams of average PLI for guitarist A and B separately. PLI was averaged across six fronto-central electrodes. Only significant PLI-values (p < 0.01) are highlighted. Time zero is time locked to the second metronome beat. Metronome beats are shown by white arrows. The time course of PLI values at the theta frequency (4.95 Hz) is depicted below the time-frequency diagram. (C) Interbrain synchronization between the two guitarists measured by IPC at the theta frequency (4.95 Hz) 140 ms after stimulus onset. Colored lines indicate synchrony between electrode pairs of the two guitarists, corresponding to significant interbrain synchronization. Only IPC values higher than 0.41 are highlighted. (D) Time-frequency diagram of the average IPC averaged across six electrode pairs. In the left diagram (A -> B), the selected electrode pairs represent phase coherence between one electrode of guitarist A (Cz) to the six fronto-central electrodes of guitarist B. Conversely, the right diagram (B -> A) refers to one electrode of guitarist B and the six fronto-central electrodes of guitarist A. Only significant IPC-values (p < 0.01) are highlighted. The time course of IPC values at the theta frequency (4.95 Hz) is depicted below the time-frequency diagram. SL = significance level.
Mentions: Synchronization within the brains as measured by PLI during the preparatory period of metronome tempo setting was highest at fronto-central sites (Figure 1A). Averaged PLI values from the six fronto-central electrodes (F3, Fz, F4, C3, Cz, and C4) were calculated in the time-frequency domain for each frequency bin and time lag. Based on the averaged PLI, synchronization within the brains was particularly high in the frequency range between 2 and 10 Hz with the maximum in the theta frequency band (3–7 Hz). This effect was strictly related to the onset of the metronome beats (Figure 1B) and was found practically in all participants (Figure S1). As for synchronization between brains as measured by IPC, coherence was also strongest for fronto-central connections (Figure 1C). Averaged IPC values from the Cz electrode of guitarist A to the six fronto-central electrodes (F3, Fz, F4, C3, Cz, and C4) of guitarist B and vice visa were thus calculated. Based on the averaged IPC, between-brain synchronization was most clearly observable in the frequency range between 3 and 8 Hz, with the maximum being around 5 Hz (Figure 1D). Interbrain phase coherence tended to be stronger in the pairs of guitarists who also showed high synchronization within brains (i.e., pairs 3, 4, and 7 in Figure S1).

Bottom Line: By applying synchronization algorithms to intra- and interbrain analyses, we found that phase synchronization both within and between brains increased significantly during the periods of (i) preparatory metronome tempo setting and (ii) coordinated play onset.Presumably, these couplings reflect similarities in the temporal properties of the individuals' percepts and actions.Whether between-brain oscillatory couplings play a causal role in initiating and maintaining interpersonal action coordination needs to be clarified by further research.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Lifespan Psychology, Max Planck Institute for Human Development, Lentzeallee 94, 14195 Berlin, Germany. lindenberger@mpib-berlin.mpg.de

ABSTRACT

Background: Brains interact with the world through actions that are implemented by sensory and motor processes. A substantial part of these interactions consists in synchronized goal-directed actions involving two or more individuals. Hyperscanning techniques for assessing fMRI simultaneously from two individuals have been developed. However, EEG recordings that permit the assessment of synchronized neuronal activities at much higher levels of temporal resolution have not yet been simultaneously assessed in multiple individuals and analyzed in the time-frequency domain. In this study, we simultaneously recorded EEG from the brains of each of eight pairs of guitarists playing a short melody together to explore the extent and the functional significance of synchronized cortical activity in the course of interpersonally coordinated actions.

Results: By applying synchronization algorithms to intra- and interbrain analyses, we found that phase synchronization both within and between brains increased significantly during the periods of (i) preparatory metronome tempo setting and (ii) coordinated play onset. Phase alignment extracted from within-brain dynamics was related to behavioral play onset asynchrony between guitarists.

Conclusion: Our findings show that interpersonally coordinated actions are preceded and accompanied by between-brain oscillatory couplings. Presumably, these couplings reflect similarities in the temporal properties of the individuals' percepts and actions. Whether between-brain oscillatory couplings play a causal role in initiating and maintaining interpersonal action coordination needs to be clarified by further research.

Show MeSH