de Jong B M, Willemsen A T, Paans A M
Department of Neurology, University Hospital Groningen, Groningen, 9700 RB, The Netherlands.
Neuroimage. 1999 Mar;9(3):290-7. doi: 10.1006/nimg.1998.0410.
By using positron emission tomography, we aimed to identify cerebral foci of neuronal activation associated with the initiation of a specific motor program. To that end, a state of repeatedly alternating in- and antiphase of bimanual flexion and extension movements was compared with similar movement responses except phase changing. This comparison provided the opportunity to eliminate confounding effects of attention and simple movements. Change between the two bimanual motor programs was related with activation at the posterior border of the left angular gyrus, the right precuneus, and the right premotor and right medial prefrontal cortex. In a subsequent experiment, with attention and random movements as additional variables, activation at the posterior border of the left angular gyrus was found at the same significance level. This posterior parietal activation may indicate an equivalence with the coding of intention in monkey posterior parietal cortex. Lesion of the left posterior parietal cortex in human gives rise to left-right disorientation and ideomotor apraxia. Our results may support the view that these symptoms reflect the inability to transpose a motor plan to the representation of a personal body scheme. Activation of the right premotor and right medial prefrontal cortex was related both to the change between motor programs and to the condition with strictly regular movement in which no additional responses were made to randomly presented signals. This is consistent with the concept that motor preparation is associated with both the selection of internally instructed movements and the suppression of irrelevant environmental stimuli.
通过使用正电子发射断层扫描技术，我们旨在确定与特定运动程序启动相关的神经元激活的脑区。为此，我们将双手反复交替进行屈伸运动的同相和反相状态与除相位变化外的类似运动反应进行了比较。这种比较提供了消除注意力和简单运动混杂效应的机会。两种双手运动程序之间的变化与左侧角回后缘、右侧楔前叶以及右侧运动前区和右侧内侧前额叶皮质的激活有关。在随后的实验中，将注意力和随机运动作为额外变量，发现左侧角回后缘的激活具有相同的显著水平。这种顶叶后部激活可能表明与猴子顶叶后部皮质中意图编码相当。人类左侧顶叶后部皮质受损会导致左右定向障碍和观念运动性失用症。我们的结果可能支持这样一种观点，即这些症状反映了无法将运动计划转化为个人身体图式的表征。右侧运动前区和右侧内侧前额叶皮质的激活既与运动程序之间的变化有关，也与严格规则运动的条件有关，在这种条件下，对随机呈现的信号不做额外反应。这与运动准备与内部指令运动的选择以及无关环境刺激的抑制都相关的概念是一致的。
