Purpose: Since rhythmical aspects of singing have been neglected up to now our objective was to investigate if it was possible to specify areas concerned with rhythm processing during simple singing.
Methods: In an event-related fMRI experiment we tested 30 healthy non-musicians with rhythm sequences, which had to be repeated as monotonously sung vowel changes with (1) regular groupings, (2) regular groupings and rests, and (3) irregular groupings.
Results: Common activations for all conditions were found in bilateral supplementary motor area, premotor cortex more distinct in the left hemisphere, left cingulate gyrus, and right basal ganglia. Only irregular groupings making the highest demands on attention, working memory, and sequencing capabilities resulted in additional activation of pars orbitalis and insula more distinct in the left hemisphere, as well as bilateral cingulate gyrus, and parietal lobes. Our analyses demonstrated that bilateral pars orbitalis (BA 47), insula, and left cingulate gyrus are core areas whose activity correlates with rhythm complexity.
Conclusions: Rhythm structure is a decisive factor concerning lateralization as well as activation of specific areas during simple singing. This finding suggests a directed use of the singing voice e.g., in order to support language rehabilitation in patients.