Functional magnetic resonance imaging during pantomiming tool-use gestures

The purpose of this study was to identify the functional fields activated i n relation to gestural movements. Using functional magnetic resonance imagi ng (fMRI), we mapped brain activity in ten right-handed, normal volunteers during activation and control tasks. The activation condition consisted of pantomiming tool-use gestures with either the left hand or right hand, wher eas the control condition comprised repetitive, oppositional movements betw een thumb and index finger. Activated cortical regions were highly laterali zed to the left hemisphere during pantomiming of tool use regardless of han d used. Praxis with either hand commonly activated the superior parietal lo bule, supplementary motor area, premotor area of the left hemisphere, and c erebellar vermis. However, minimal activation occurred in the inferior pari etal lobule, which has been known to be a critical area for praxis generati on. Compared with left-hand praxis, right-hand praxis exhibited additional activation in the left putamen and posterior part of the left inferior temp oral region. Our findings concur with neuropsychological observations that the left hemisphere in right-handers mediates programming and executing ski lled movements and that, within the left hemisphere, praxis is predominantl y subserved by the parietal lobe, supplementary motor area, and premotor ar ea. However, unlike previous lesion studies, the results of our fMRI study suggested that the superior parietal lobule more likely than the inferior p arietal lobule play an important role in gesture production.