Patients with Parkinson's disease (PD) suffer from gait disturbance that, in some patients, can be improved by rhythmic stimulation. This effect is useful for their rehabilitation, but its physiological mechanism is not yet well understood. The purpose of this study is to investigate brain activation patterns with functional magnetic resonance imaging (fMRI) in patients with PD while they are imaging gait with and without rhythmic stimulation.

The participants were 27 right-handed patients with PD (mean age: 76.3±6.6, 11 male), whose Yahr stages ranged from 2 to 3. They could walk independently, had no cognitive impairment, and could walk more smoothly with rhythmic stimulation than without it. As a control group, we examined 7 healthy 25 right-handed volunteers (mean age: 72.0±5.3, 13 males). The participants were asked to image gait with rhythmic stimulation (beep on 100 beats per minute) or with white noise during the fMRI imaging.

In patients with PD, with rthmic sound, the activation pattern was limited to supplementary motor area (SMA) and precentral lobule, while with white noise, the activation pattern was more widespread, including precuneus as well as SMA and precentral lobule (P<0.001, (uncorrected)). In healthy controls, the activation was limited to SMA and precentral lobule both with rhythmic stimulation and with white noise.

Both SMA and precentral lobule were activated while other regions including precuneus were less activated with rhythmic stimulation in patients with PD. This result may suggest that rhythmic stimulation can suppress the overactivation of precuneus to improve the attention and to correct the motor programs for the gait function in these patients. In this study, we could suggest the mechanism of the immediate effect of gait improvement with rhythmic stimulation.