The cortical activation effect of phonation on a motor task: a functional MRI study.

It is well-known that sound production can affect the motor system. We investigated whether a short, loud phonation affected cortical activation caused by a motor task using functional MRI. Fifteen right-handed healthy subjects were recruited for this study. We compared the cortical activation caused by the performance of a motor task (right hand grasp-release movements) to that caused by the performance of the motor task with phonation("ah" sound). We found that performance of the motor task with phonation resulted in less activation in the primary sensori-motor cortex than did the performance of the motor task alone. It seemed that phonation during the motor task enhanced the efficiency of cortical activation compared to that caused by the motor task alone.