Perhaps the ICA underestimated this spatial segregation, causing voxels from one network to distort the task-component loadings from the other and masking the contribution of a diffuse

higher-order “g” factor. This objection is highly unlikely for several reasons. First, LY2157299 in vitro while ICA seeks to maximize independence, it does not necessarily derive completely independent components. For example, in the current study, the MDwm and MDr components did show the expected negative correlation across voxels (r = −0.19). Second, such a close conformity between the second-order correlations from the simulated and behavioral models would have been highly unlikely to occur by chance alone if the ICA had failed. Furthermore, if the networks are spatially separable, then it should be possible to take relatively unmixed measures of their task-related activations by examining the centers of each cluster, where there is minimal network overlap. For example, when mean task activation levels were extracted from 5 mm spherical ROIs centered on peak IFO and IFS coordinates within the MDwm and MDr networks bilaterally, a marked double dissociation was evident across tasks. Specifically, there was either strong coactivation of regions or strong activation in one region and virtually no activation in the

other dependent on the task context (Table S5). This is clearly the pattern of results that would be expected if the ROIs were placed exclusively within functionally dissociable and spatially separable networks. Nonetheless, when the 2F simulations see more were rerun based on these IFS and IFO activation levels, the second-order

correlation between the estimated oblique components was not diminished but, rather, formed a precise match to the Internet behavioral data (r = 0.47, SD ± 0.02). Thus, while the contribution of diffuse factors should not be entirely discounted, the results accord particularly closely with the view that the higher-order “g” component is primarily accounted for by cognitive tasks recruiting multiple functionally dissociable brain networks. Indeed, from a phenomenological to perspective, the idea that tasks tend to corecruit multiple functional brain networks makes intuitive sense, as generating a task that depends on any single cognitive process is likely to be rather intractable. Consider a simple working memory task, in which the spatial locations of a sequence of flashes must be observed, maintained, and repeated (spatial span). Even in this simple context, the participant must comprehend the written instructions, otherwise, they may report the correct locations but in the incorrect sequence. More importantly, people often apply chunking strategies when encoding information in short-term memory in order to generate a more efficient memory trace.