The mean intensity ofo activation than the number of activated voxels is a better index to reflect the levels of visuospatial performance.

This study is to identify the more sensitive method to measure the brain activation by the visuospatial performance level by comparing two different methods of measuremtnt (i.e., a method calculating the number of activated voxels and the other, the mean intensity of activated voxels). Sixteen right-handed male college students (mean age 23.2 years) participated in this study and function brain images were scanned with a 3T MRI using the single-shot EPI method during visuospatial performance. There found no brain areas with correlation between the visuospatial performance level and number of activated voxels. However, there found a sifgnificant correlatgion between the visuospatial performance level and the mean intensity of selected activated voxels in the parietal, frontal, and other areas.f In conclusion, the method of meanintensity rather than the one of the number is considered as a better index.