FV 7 Keeping the beat: stimulus-related neuronal oscillations relate to musical training and performance of polyrhythmic drumming

Abstract

Introduction: When listening to music, one can effortlessly tap or clap along—and continue to do so even after the music stops. This ability is supported by neuronal ensembles in sensory cortices synchronizing their activity to the period of the repeating musical stimulus and sustaining this activity for a brief period despite the cessation of the stimulus. This process of neural entrainment facilitates the prediction of the future behaviour of rhythmic stimuli, even in case of multiple superposed rhythms (polyrhythms). This EEG study investigates the relationship between musical training, neural entrainment strength, and performance in a behavioral task using an auditory polyrhythmic paradigm. Methods: 32-multichannel EEG was recorded from 20 healthy subjects. In each of the 150 trials per subject, 3 bars of a polyrhythm were presented consisting of a simultaneously sounding “duple” (1.16 Hz) and “triple” (1.75 Hz) drumming rhythm. After an additional bar of silence, subjects were requested to complete one of the rhythms in the next bar by striking a drum. The selection of the rhythm was indicated after the bar of silence—requiring subjects to track both rhythms simultaneously during the silent break. EEG activity at the two target frequencies of the polyrhythm was extracted by Fourier transformation and Spatio-Spectral Decomposition (SSD). The resulting best two components for each frequency, together with a measure of individual musical training and experimental time (possibly capturing both fatigue and training effects) were regressed to performance using a random effects within-between (REWB) model. Results: Individual levels of musical training were shown to significantly correlate with the strength of neuronal entrainment as detected by SSD. Additionally, the REWB model showed that the average strength of a subject’s neural entrainment significantly correlated with the average performance of that subject for the duple rhythm but not for the triple rhythm. No significant within-subject effects were seen for either of the rhythms. Discussion and Significance: The study’s findings draw a connection between individual musicality, neuronal entrainment to auditory rhythms, and performance according to these rhythms. On a general scope, this suggests that neuronal oscillations relate to temporal precision and maintenance of rhythmic actions. The causal role of neuronal oscillations with respect to rhythmic behaviour, however, remains a target for future research, e.g., using non-invasive brain stimulation. Further, study of longitudinal effects could provide insight into whether the strength of entrainment represents an individual trait of musical people or a training effect.