Numerous brain imaging studies identified a domain-general or “multiple-demand” (MD) activation pattern accompanying many tasks and may play a core role in cognitive control. Though this finding is well established, the limited spatial localization provided by traditional imaging methods precluded a consensus regarding the precise anatomy, functional differentiation, and connectivity of the MD system. To address these limitations, we used data from 449 subjects from the Human Connectome Project, with the cortex of each individual parcellated using neurobiologically grounded multimodal MRI features. The conjunction of three cognitive contrasts reveals a core of 10 widely distributed MD parcels per hemisphere that are most strongly activated and functionally interconnected, surrounded by a penumbra of 17 additional areas. Outside cerebral cortex, MD activation is most prominent in the caudate and cerebellum. Comparison with canonical resting-state networks shows MD regions concentrated in the fronto-parietal network but also engaging three other networks. MD activations show modest relative task preferences accompanying strong co-recruitment. With distributed anatomical organization, mosaic functional preferences, and strong interconnectivity, we suggest MD regions are well positioned to integrate and assemble the diverse components of cognitive operations. Our precise delineation of MD regions provides a basis for refined analyses of their functions.

AbstractNumerous brain imaging studies identified a domain-general or “multiple-demand” (MD) activation pattern accompanying many tasks and may play a core role in cognitive control. Though this finding is well established, the limited spatial localization provided by traditional imaging methods precluded a consensus regarding the precise anatomy, functional differentiation and connectivity of the MD system. To address these limitations, we used data from 449 subjects from the Human Connectome Project, with cortex of each individual parcellated using neurobiologically grounded multi-modal MRI features. The conjunction of three cognitive contrasts reveals a core of 10 widely distributed MD parcels per hemisphere that are most strongly activated and functionally interconnected, surrounded by a penumbra of 17 additional areas. Outside cerebral cortex, MD activation is most prominent in the caudate and cerebellum. Comparison with canonical resting state networks shows MD regions concentrated in the fronto-parietal network but also engaging three other networks. MD activations show modest relative task preferences accompanying strong co-recruitment. With distributed anatomical organization, mosaic functional preferences, and strong interconnectivity, we suggest MD regions are well positioned to integrate and assemble the diverse components of cognitive operations. Our precise delineation of MD regions provides a basis for refined analyses of their functions.

How does organized cognition arise from distributed brain activity? Recent analyses of fluid intelligence suggest a core process of cognitive focus and integration, organizing the components of a cognitive operation into the required computational structure. A cortical 'multiple-demand' (MD) system is closely linked to fluid intelligence, and recent imaging data define nine specific MD patches distributed across frontal, parietal, and occipitotemporal cortex. Wide cortical distribution, relative functional specialization, and strong connectivity suggest a basis for cognitive integration, matching electrophysiological evidence for binding of cognitive operations to their contents. Though still only in broad outline, these data suggest how distributed brain activity can build complex, organized cognition. Organizing Distributed Brain ActivityOrganized cognition of any kind arises from widely distributed brain activity. An immediate question is how such activity is integrated, allowing just the right cognitive contents to be combined in just the right way for current purposes. Though much is certainly unknown, an outline view of the relevant psychological and physiological mechanisms is beginning to appear. In this opinion article, we describe recent progress towards a whole-brain understanding of cognitive integration.We begin with recent work on the cognitive mechanisms of fluid intelligence (see Glossary). Theoretical accounts of fluid intelligence focus on processes of cognitive control [1-3] and cognitive integration [4] and, based on recent findings, we suggest a synthesis of these two approaches. Results from brain imaging [5-7] and lesion [8] studies relate fluid intelligence to a well-known control network in the brain, which previously we have called the multiple-demand (MD) system [9,10]. We describe recent studies on the detailed anatomy and physiology of MD activity and how they begin to illuminate the physiological underpinning of cognitive control and integration. In broad outline, these findings suggest how distributed brain activity builds organized cognition. We conclude with some of the many questions that this scheme raises for future work. Fluid Intelligence and Attentional IntegrationA fundamental psychometric discovery is positive manifold: to some extent, all tests of different cognitive abilities tend to have positive correlations [11,12], even those that on the surface are dissimilar. In his foundational work, Spearman [11] proposed that some general or g factor contributes to success in any task. If this model is fit to correlational data, novel problemsolving tests turn out to be excellent measures of g, reflecting the fact that, in a diverse task battery, it will be these tests that have the largest average correlations with a wide range of others.Well known examples are matrix problems (Figure 1A) [13,14], series completions [15], etc. The ability measured in such tests has been called 'fluid intelligence'. Later, we consider several possible contributors to positive manifold, but meanw...