April 04, 2009

Brains of Guitarists in Unison Harmonize Too

Iron Maiden guitarists in concert depicting the synchronization of guitarsDuring the 80's, I listened to heavy metal bands like Iron Maiden and Metallica, although I couldn't follow their lyrics always. What used to captivate me in awe was how the guitarists synchronized themselves together so well. It apparently seemed as if only one guitar was playing in the background, which on closer scrutiny revealed the actual truth: it was really a duet. It is only now that scientists are beginning to find the secret behind this 'time and phase synchrony'.

Scientists at the Max Planck Institute for Human Development in Berlin, have shown that musicians playing the same tune have their brains 'coupled' together. They started off experimenting with 8 such musician pairs. They first recorded the brain activity of each
'duetter' by taking their electroencephalographic recordings (EEG). The musicians kept the EEG set-up atop their heads throughout the experiment.

After taking the baseline EEG recordings, the researchers then made the guitarists to listen to metronome beats. Metronome beats are beats of sound that occur periodically and are used to keep track of time. They found that the EEG activities of the players were synchronized to that of the metronome beats. Next, the lead guitarist of the pair had to tap his guitar in a gesture to signal his partner as to when and at what speed they would begin. At this point, the researchers looked at the brainwaves of the guitarists again and found that the EEG of both the guitarists were in synchrony to each other (and no longer to the metronome beats). Curiously, this happened even before the actual performance began. This oscillatory synchronization was found to be especially stronger at the frontal and central electrode sites (of the EEG leads). This may indicate simultaneous firing of the motor and somatosensory neurons.

This experiment also throws light as to how empathy and the 'mirror neuron network' might be working. These inter-personally coordinated behaviors will only result if they happen fast and both the sensory and the motor actions are coordinated. Certainly, there has to be some kind of a feedback between the pair for effective harmonization to occur.

It has been previously seen that in addition to the EEG coupling; magnetoencephalography (MEG; measures the magnetic field around the skull) and electromyography (EMG: measures the muscle activity) related well between neuronal activity of a person to the voluntary activity of the same person. The new finding may help us probe the basis of social interaction but it also poses a question: how do the performers synchronize and through which media? You can find videos of duetting guitarists and the corresponding EEG recordings at Biomedcentral.

P.S. Finally, let me allow to propose 2 mechanisms which may be responsible for this apparent 'phase lock'. Firstly, the performers have a very clear idea about the piece they were about to perform, since they are well rehearsed. Naturally, the guitarists are in tune with the next intermezzo and if they were to strum chord C major, their corresponding motor planning areas would become active. It is known that the motor planning areas become electrically active even before the execution of actual action (1). Secondly, we can also assume that they, being emphatically coupled to the music, get connected across by mirror neurons. The mirror neuron system then does the rest: driving the players in a rapturous synchrony.

ResearchBlogging.orgLindenberger, U., Li, S., Gruber, W., & Müller, V. (2009). Brains swinging in concert: cortical phase synchronization while playing guitar BMC Neuroscience, 10 (1) DOI: 10.1186/1471-2202-10-22 Last modified: Jan 19, 2010
Reference:(1) William F. Ganong, Control of Posture & Movement, 22nd Ed, Review of Medical Physiology, Page: 202

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