Functional brain imaging shows many specializations in the human brain. At the same time, it reveals something unexpected – a specific set of regions in the frontal and parietal cortex, active for many different kinds of cognitive demand. We call this multiple-demand or MD cortex. The network was originally defined using predominantly PET data:
[Duncan and Owen, 2000] [Duncan, 2006]
The definition of the MD system has been further refined using fMRI data from seven different tasks of varying demand, described in the publication:
Fedorenko, E., Duncan, J., & Kanwisher, N. (in press). Language-selective and Domain-general Regions Lie Side by Side within Broca's Area. Current Biology.
The full unthresholded volume can be downloaded in Nifti format from this link.
The units are t-statistics from contrasts that isolate cogntive demand, averaged across the seven tasks. The figure below shows the main foci of the multiple demand system when this volume is thresholded at a value of t>1.5.