Event-related potential study of frontal activity during imagination of rhythm.

In 11 healthy volunteers, we used event-related potentials (ERP) to investigate the frontal activity associated with imagining a beat. In imagery sessions, subjects were asked to imagine a rhythm during a silent recording period following a series of guide sounds played at 1 Hz. In control sessions, subjects were asked to imagine a vowel sound ("a") continuously during the silent recording period. In eight subjects, relative negative potentials were recorded during imagery sessions (compared with potentials in control sessions), with timing that was similar to that of the guide sounds. Activity in the left frontal region was more significant than that in other areas during beat imagination. These data indicate that a semantic strategy for simple rhythm imagery might involve temporary phasic activation in the left frontal area, although rhythm production and perception might be generated in the right side, as reported in previous studies.