Honey G D, Bullmore E T, Sharma T
Section of Cognitive Psychopharmacology, King's College, London, United Kingdom.
Neuroimage. 2000 Nov;12(5):495-503. doi: 10.1006/nimg.2000.0624.
We used multislice functional magnetic resonance imaging (fMRI) to investigate the association between behavioral and neurophysiological measures of working memory task performance in 20 right-handed male healthy volunteers. Images were acquired over a 5-min period at 1.5 Tesla. We used a periodic design, alternating 30-s blocks of the "n-back" working memory task with 30-s blocks of a sensorimotor control task to activate verbal working memory systems. The power of functional response to the task was estimated by sinusoidal regression at each voxel. The relationship between power of fMRI response and mean reaction time over all 11 working memory trials was explored by multiple regression, with age and mean reaction time to the control task as covariates, at voxel and regional levels of analysis. All subjects were able to perform the n-back task accurately. A spatially distributed network was activated, including dorsolateral prefrontal cortex, inferior frontal gyrus, lateral premotor cortex, and supplementary motor area (SMA) in the frontal lobes. More posteriorly, there were major foci of activation in parietal and occipitoparietal cortex, precuneus, lingual, and fusiform gyri of the ventral occipital lobe, inferior temporal gyrus, and cerebellum. The power of functional response was positively correlated with reaction time in bilateral posterior parietal cortex (Talairach coordinates in x, y, z (mm) 35, -44, 37 and -32, -56, 42), indicating that subjects who found the task difficult, and responded with a slower reaction time, tended to activate these regions more powerfully. One interpretation of this regionally specific relationship between prolonged reaction time and increased power of posterior parietal activation is consistent with prior studies identifying similar areas of parietal cortex as the site of the phonological storage function in verbal working memory.
我们使用多层功能磁共振成像（fMRI）来研究20名右利手男性健康志愿者工作记忆任务表现的行为学与神经生理学指标之间的关联。在1.5特斯拉的磁场强度下，于5分钟内采集图像。我们采用周期性设计，将“n-back”工作记忆任务的30秒时段与感觉运动控制任务的30秒时段交替进行，以激活言语工作记忆系统。通过对每个体素进行正弦回归来估计对任务的功能反应功率。在体素和区域分析水平上，采用多元回归方法，以年龄和对控制任务的平均反应时间作为协变量，探讨fMRI反应功率与所有11次工作记忆试验的平均反应时间之间的关系。所有受试者均能准确完成n-back任务。激活了一个空间分布网络，包括额叶的背外侧前额叶皮质、额下回、外侧运动前皮质和辅助运动区（SMA）。更靠后的区域，在顶叶和枕顶叶皮质、楔前叶、枕叶腹侧的舌回和梭状回、颞下回以及小脑中存在主要激活灶。双侧后顶叶皮质（Talairach坐标x、y、z（毫米）为35, -44, 37和-32, -56, 42）的功能反应功率与反应时间呈正相关，这表明觉得任务困难且反应时间较慢的受试者往往会更强烈地激活这些区域。反应时间延长与后顶叶激活功率增加之间这种区域特异性关系的一种解释与先前的研究一致，这些研究将顶叶皮质的类似区域确定为言语工作记忆中语音存储功能的部位。
