Basis of executive functions in fine-grained architecture of cortical and subcortical human brain networks

Theoretical models suggest executive functions are supported by both domain-general and domain-specific processes. While some brain imaging studies claim executive tasks recruit a domain-general multiple-demand (MD) brain system, many studies argue the spatially coarse results of traditional imaging methods have blurred fine-grained functionally fractionated domain-specific systems into one. To address this challenge, we scanned participants using the high spatial resolution multimodal MRI approach of the Human Connectome Project while they performed tasks targeting executive demands of updating, shifting and inhibition. The results show that different executive activations overlap, at the single subject level, within MD regions. Critically, each task’s topography shifts within MD regions to form a unique intersection with adjacent fine-grained resting-state networks. In this intersection, the strongest activations arise at neurobiologically defined network borders. Outside cerebral cortex, matching results are seen in circumscribed regions of the caudate nucleus, thalamus and cerebellum. Using precise imaging methods, these results suggest a novel framework whereby partially-specialised networks recruit neighbouring MD areas to generate distinct executive functions.