Samuel M, Williams S C, Leigh P N, Simmons A, Chakraborti S, Andrew C M, Friston K J, Goldstein L H, Brooks D J
MRC Cyclotron Unit, Hammersmith Hospital, London, UK.
Neurology. 1998 Dec;51(6):1567-75. doi: 10.1212/wnl.51.6.1567.
To use functional MRI (fMRI) to study grouped patterns of cerebral activation and the course of hemodynamic responses during performance of two activation tasks (paradigms) using a hand-held joystick to perform movements in a repetitively fixed direction and movements in freely selected random directions.
Evidence from lesion, electrophysiologic, and functional imaging studies implicates prefrontal and mesial frontal cortex in motor preparation and primary motor cortex in motor execution. fMRI can be used to study cerebral activation and has practical advantages over other methods of functional neuroimaging.
We acquired 100 multislice T2*-weighted data sets from five healthy volunteers during performance of each paradigm using conventional fMRI. For each paradigm, rest and movement epochs were alternated every 30 seconds. After coregistration and spatial normalization, we combined the data for group studies. We used statistical parametric mapping to compare the early (first 15 seconds) components of the movement epochs with rest as well as the late (last 15 seconds) components of the movement epochs with rest.
During the early phase of both paradigms, significant activation was present in rostral and caudal mesial premotor cortex. Right prefrontal cortex was significantly activated during the early component of freely selected joystick movements. Activation of rostral supplementary motor area was maintained during the late component of freely selected movements but decreased during repetitively fixed movements. In contrast, significant activation in contralateral sensorimotor cortex was maintained during both early and late components of both paradigms.
fMRI can detect cortical activation. The temporal resolution of fMRI also allows adaptation of blood oxygenation level-dependent (BOLD) contrast signal to be detected in association cortex. However, the level of BOLD contrast signal in primary motor cortex remained significantly elevated throughout task performance.
使用功能磁共振成像（fMRI）研究在两项激活任务（范式）执行过程中大脑激活的分组模式以及血流动力学反应过程。这两项任务分别是使用手持操纵杆在重复固定方向上进行运动，以及在自由选择的随机方向上进行运动。
来自病变、电生理和功能成像研究的证据表明，前额叶和内侧额叶皮质参与运动准备，而初级运动皮质参与运动执行。fMRI可用于研究大脑激活，并且相对于其他功能神经成像方法具有实际优势。
我们在每位健康志愿者执行每种范式的过程中，使用传统fMRI采集了100个多层T2 *加权数据集。对于每种范式，静息期和运动期每30秒交替一次。在进行配准和空间归一化后，我们将数据合并用于组间研究。我们使用统计参数映射来比较运动期的早期（前15秒）成分与静息期，以及运动期的晚期（最后15秒）成分与静息期。
在两种范式的早期阶段，额内侧运动前皮质的嘴侧和尾侧均有显著激活。在自由选择操纵杆运动早期成分期间，右侧前额叶皮质有显著激活。在自由选择运动的晚期成分期间，嘴侧辅助运动区保持激活，但在重复固定运动期间激活减少。相比之下，在两种范式的早期和晚期成分期间，对侧感觉运动皮质均保持显著激活。
fMRI可以检测到皮质激活。fMRI的时间分辨率还允许在联合皮质中检测到与血氧水平依赖（BOLD）对比信号的适应性变化。然而，在整个任务执行过程中，初级运动皮质中的BOLD对比信号水平仍显著升高。
