Functional MRI of the supplementary motor area: comparison of motor and sensory tasks.

PURPOSE

The purpose of this work was to assess the activation of the supplementary motor area (SMA) during simple motor, complex motor, hot sensory, and touch sensory tasks.

METHOD

Functional MRI (fMRI) was performed in eight right-handed healthy volunteers. There were four tasks: simple motor, complex motor, hot sensory, and touch sensory. The number of pixels and the average percentage change of signal intensity in the activated SMA were obtained during the four tasks and then compared.

RESULTS

The SMA was consistently activated on fMRI during both motor and sensory tasks. The average number of activated pixels during the complex motor task was more than the number during the hot sensory task, but the difference was not statistically significant. The average number of activated pixels during the complex motor task was greater than during the simple motor task. The average number of activated pixels during the hot sensory task was greater than during the touch sensory task. The average percentage change of signal intensity was statistically significant between the simple motor and the complex motor task. The average percentage change of signal intensity was not statistically significant between the complex motor and the hot sensory task.

CONCLUSION

The SMA is activated in both motor and sensory tasks. The degree of activation of the SMA differs according to the type of task.