Response-selection-related parietal activation during number comparison
Response-selection-related parietal activation during number comparison
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DOI：
10.1162/0898929042568442
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发表时间：
2004-11-01
影响因子：
3.2
通讯作者：
Rushworth, MFS
中科院分区：
文献类型：
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作者：
Göbel, SM;Johansen-Berg, H;Rushworth, MFS
数字比较的神经影像学研究一直发现顶内沟（IPS）的激活。最近，有人提出，IPS的激活随着被比较的数字之间的距离而变化。在数字比较中，数字和参考之间的距离越小，反应时间（RT）越长。然而，右侧或左侧IPS的激活也与注意力和有意选择有关。这是可能的，因此，在这个区域的活动是一个更基本的刺激和反应选择过程与RT的变化的反映。这个功能磁共振成像实验研究的影响，独立于RT的数值距离。此外，激活在数字比较的个位数和两位数的刺激进行了比较。在数字比较数字块期间，受试者必须指出数字是大于还是小于参考数字（5或65）。在控制块，他们被要求执行知觉任务（垂直线存在/不存在）的数字或非数字刺激。数字比较与休息产生了一个大的双边顶叶后额叶网络。然而，没有地区显示更多的激活在数字比较比在控制任务。此外，在比较相隔很小距离的数字时，没有哪个区域比比较相隔很大距离的数字时更活跃，反之亦然。左侧顶叶后额叶网络变化显着偏侧与RT。我们的研究结果表明，幅度和数字距离相关的IPS激活可能很难分开的基本刺激和反应选择过程与RT的变化。与其他参数（如空间）一样，幅度可以在顶叶皮层的反应选择上下文中表示。在这方面，人类IPS中的幅度表示可能与其他非人类灵长类动物中的幅度表示相似。
Neuroimaging studies of number comparison have consistently found activation in the intraparietal sulcus (IPS). Recently, it has been suggested that activations in the IPS vary with the distance between the numbers being compared. In number comparison, the smaller the distance between a number and the reference the longer the reaction time (RT). Activations in the right or left IPS, however, have also been related to attentional and intentional selection. It is possible, therefore, that activity in this region is a reflection of the more basic stimulus and response-selection processes associated with changes in RT. This fMRI experiment investigated the effect of numerical distance independently from RT. In addition, activations during number comparison of single-digit and double-digit stimuli were compared. During number comparison digit blocks, subjects had to indicate whether digits were greater or smaller than a reference ( 5 or 65). In control blocks, they were asked to perform a perceptual task ( vertical line present/absent) on either numerical or nonnumerical stimuli. Number comparison versus rest yielded a large bilateral parietal-posterior frontal network. However, no areas showed more activation during number comparison than during the control tasks. Furthermore, no areas were more active during comparison of numbers separated by a small distance than comparisons of those separated by a large distance or vice versa. A left-lateralized parietal-posterior frontal network varied signifi-lateralized significantly with RT. Our findings suggest that magnitude and numerical-distance-related IPS activations might be difficult to separate from fundamental stimulus and response-selection processes associated with RT changes. As is the case with other parameters, such as space, magnitude may be represented in the context of response selection in the parietal cortex. In this respect, the representation of magnitude in the human IPS may be similar to the representation of magnitude in other nonhuman primates.