In time with rhythms:Beat perception and sensorimotor synchronisation

Music and beat perception are strongly connected to movement, a phenomenon known as sensorimotor synchronisation. Neurophysiologically, simple metronome-like beat sounds entrain neural oscillations, so that the brain oscillates with the same frequency as the beat frequency. The usefulness of being entrained to a beat lies in the increased accuracy of predicting crucial future events (e.g. the next beat). However, in our everyday environment beats rarely occur without being embedded in rhythmical and metrical structures (e.g. music). The present work seeks to examine how more complex rhythmical sounds are creating temporal expectancies and how multiple explicit metrical structures are represented in the brain. Electroencephalogram recordings were obtained while participants listened to beat-sounds varying in metrical complexity (low vs. high) and tempo (fast vs. slow). Their task was to synchronise finger movements to the lowest metrical level beat. We found that high metrical complexity facilitates synchronisation to slower beats. Looking at the frequency spectres of the obtained EEG data, entrained oscillations not only emerged at the lowest metrical level beat frequencies that occurred in every experimental condition, but also at higher metrical level beat frequencies in the high complexity conditions. Being entrained to multiple metrical structures could provide additional temporal information which can be used to improve synchronisation performance. Taken together, results highlight the dynamic, proactive and predictive character of brain functions