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Summary: Behavioral/Systems/Cognitive
Triangulating a Cognitive Control Network Using
Diffusion-Weighted Magnetic Resonance Imaging (MRI)
and Functional MRI
Adam R. Aron,1,2 Tim E. Behrens,3,4 Steve Smith,3 Michael J. Frank,5 and Russell A. Poldrack2
1Department of Psychology, University of California San Diego, La Jolla, California 92093, 2Department of Psychology and Brain Research Institute,
University of California Los Angeles, Los Angeles, California 90095, 3Center for Functional Magnetic Resonance Imaging of the Brain and 4Department of
Experimental Psychology, University of Oxford, Oxford OX3 9DU, United Kingdom, and 5Department of Psychology, University of Arizona, Tucson,
Arizona 85721
The ability to stop motor responses depends critically on the right inferior frontal cortex (IFC) and also engages a midbrain region
consistent with the subthalamic nucleus (STN). Here we used diffusion-weighted imaging (DWI) tractography to show that the IFC and
the STN region are connected via a white matter tract, which could underlie a "hyperdirect" pathway for basal ganglia control. Using a
novelmethodof"triangulation"analysisoftractographydata,wealsofoundthatboththeIFCandtheSTNregionareconnectedwiththe
presupplementary motor area (preSMA). We hypothesized that the preSMA could play a conflict detection/resolution role within a
network between the preSMA, the IFC, and the STN region. A second experiment tested this idea with functional magnetic resonance
imaging (fMRI) using a conditional stop-signal paradigm, enabling examination of behavioral and neural signatures of conflict-induced
slowing.ThepreSMA,IFC,andSTNregionweresignificantlyactivatedthegreatertheconflict-inducedslowing.Activationcorresponded
strongly with spatial foci predicted by the DWI tract analysis, as well as with foci activated by complete response inhibition. The results
illustrate how tractography can reveal connections that are verifiable with fMRI. The results also demonstrate a three-way functional
anatomical network in the right hemisphere that could either brake or completely stop responses.
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