Rhythmic brain activities related to singing in humans.

To investigate the motor control related to sound production, we studied cortical rhythmic changes during continuous vocalization such as singing. Magnetoencephalographic (MEG) responses were recorded while subjects spoke in the usual way (speaking), sang (singing), hummed (humming) and imagined (imagining) a popular song. The power of alpha (8-15 Hz), beta (15-30 Hz) and low-gamma (30-60 Hz) frequency bands was changed during and after vocalization (singing, speaking and humming). In the alpha band, the oscillatory changes for singing were most pronounced in the right premotor, bilateral sensorimotor, right secondary somatosensory and bilateral superior parietal areas. The beta oscillation for the singing was also confirmed in the premotor, primary and secondary sensorimotor and superior parietal areas in the left and right hemispheres where were partly activated even for imagined a song (imaging). These regions have been traditionally described as vocalization-related sites. The cortical rhythmic changes were distinct in the singing condition compared with the other vocalizing conditions (speaking and humming) and thus we considered that more concentrated control of the vocal tract, diaphragm and abdominal muscles is responsible. Furthermore, characteristic oscillation in the high-gamma (60-200 Hz) frequency band was found in Broca's area only in the imaging condition and might occur singing rehearsal and storage process in Broca's area.