Numerous brain lesion and fMRI studies have linked individual differences in executive abilities and fluid intelligence to brain regions of the fronto-parietal “multiple-demand” (MD) network. Yet, fMRI studies have yielded conflicting evidence as to whether better executive abilities are associated with stronger or weaker MD activations and whether this relationship is restricted to the MD network. Here, in a large-sample (n = 216) fMRI investigation, we found that stronger activity in MD regions – functionally defined in individual participants – was robustly associated with more accurate and faster responses on a spatial working memory task performed in the scanner, as well as fluid intelligence measured independently (n = 114). In line with some prior claims about a relationship between language and fluid intelligence, we also found a weak association between activity in the brain regions of the left fronto-temporal language network during an independent passive reading task, and performance on the working memory task. However, controlling for the level of MD activity abolished this relationship, whereas the MD activity-behavior association remained highly reliable after controlling for the level of activity in the language network. Finally, we demonstrate how unreliable MD activity measures, coupled with small sample sizes, could falsely lead to the opposite, negative, association that has been reported in some prior studies. Taken together, these results demonstrate that a core component of individual differences variance in executive abilities and fluid intelligence is selectively and robustly positively associated with the level of activity in the MD network, a result that aligns well with lesion studies.

许多脑部病变和功能磁共振成像研究已将执行能力和流体智力的个体差异与额顶叶“多重需求”（MD）网络的大脑区域联系起来。然而，关于更好的执行能力是否与更强或更弱的 MD 激活相关，以及这种关系是否仅限于 MD 网络，功能磁共振成像研究得出了相互矛盾的证据。在这里，在一项大样本（n = 216）fMRI调查中，我们发现MD区域的更强活动（在个体参与者中进行功能定义）与扫描仪中执行的空间工作记忆任务的更准确和更快的反应密切相关，以及独立测量的流体智力（n = 114）。与之前关于语言和流体智力之间关系的一些说法一致，我们还发现在独立被动阅读任务期间左额颞叶语言网络的大脑区域的活动与工作记忆任务的表现之间存在微弱的关联。然而，控制 MD 活动水平消除了这种关系，而在控制语言网络的活动水平后，MD 活动-行为关联仍然高度可靠。最后，我们证明了不可靠的 MD 活性测量，加上小样本量，如何可能错误地导致一些先前研究中报告的相反的、负面的关联。总而言之，这些结果表明，执行能力和流体智力个体差异的核心组成部分与 MD 网络的活动水平有选择性地、稳健地正相关，这一结果与病变研究非常吻合。