Jahanshahi M, Dirnberger G, Fuller R, Frith C D
Department of Clinical Neurology, Institute of Neurology, The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, United Kingdom.
Neuroimage. 2000 Dec;12(6):713-25. doi: 10.1006/nimg.2000.0647.
Random number generation (RNG) engages a number of executive processes. We used positron emission tomography (PET) to measure regional cerebral blood flow (rCBF) in six volunteers who performed RNG and a control counting (COUNT) task at six rates paced by a tone. This provided a systematic variation of difficulty of RNG. Relative to COUNT, RNG was associated with significant activation of the left dorsolateral prefrontal cortex (DLPFC), the anterior cingulate, the superior parietal cortex bilaterally, the right inferior frontal cortex, and the left and right cerebellar hemispheres. Faster rates of RNG were associated with a significant decrease in regional cerebral blood flow (rCBF) in the left and right DLPFC and the right superior parietal cortex. rCBF in the left DLPFC was significantly and negatively associated with count score 1, a measure of habitual counting during RNG. These results are discussed in relation to the network modulation model of RNG developed on the basis of our previous studies using transcranial magnetic stimulation and dual task paradigms. This suggests that during RNG, suppression of habitual counting is achieved through the modulatory (inhibitory) influence of the left DLPFC over a number associative network distributed in the superior temporal cortex. At faster rates of RNG the synchronization demands of paced RNG result in the breakdown of this modulatory influence, which is evident from decreased rCBF in the left DLPFC and increased habitual counting at faster rates.
随机数生成（RNG）涉及多个执行过程。我们使用正电子发射断层扫描（PET）来测量六名志愿者的局部脑血流量（rCBF），这些志愿者在由音调设定的六种速率下执行RNG和对照计数（COUNT）任务。这提供了RNG难度的系统性变化。相对于COUNT，RNG与左侧背外侧前额叶皮质（DLPFC）、前扣带回、双侧顶上叶皮质、右侧额下回以及左右小脑半球的显著激活相关。更快的RNG速率与左右DLPFC和右侧顶上叶皮质的局部脑血流量（rCBF）显著降低相关。左侧DLPFC的rCBF与计数分数1显著负相关，计数分数1是RNG期间习惯性计数的一种度量。这些结果将结合基于我们之前使用经颅磁刺激和双任务范式的研究开发的RNG网络调制模型进行讨论。这表明在RNG期间，通过左侧DLPFC对分布在颞上叶皮质的数字联想网络的调制（抑制）影响来实现对习惯性计数的抑制。在更快的RNG速率下，有节奏的RNG的同步需求导致这种调制影响的瓦解，这从左侧DLPFC中rCBF的降低和更快速率下习惯性计数的增加中可以明显看出。
