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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 novel method of "triangulation" analysis of tractography data, we also found that both the IFC and the STN region are connected with the 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. The preSMA, IFC, and STN region were significantly activated the greater the conflict-induced slowing. Activation corresponded 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.

Original publication

DOI

10.1523/jneurosci.0519-07.2007

Type

Journal article

Journal

The Journal of neuroscience : the official journal of the Society for Neuroscience

Publication Date

04/2007

Volume

27

Pages

3743 - 3752

Addresses

Department of Psychology, University of California San Diego, La Jolla, California 92093, USA. adamaron@ucsd.edu

Keywords

Nerve Net, Humans, Magnetic Resonance Imaging, Diffusion Magnetic Resonance Imaging, Brain Mapping, Photic Stimulation, Cognition, Psychomotor Performance, Reaction Time, Adult, Female, Male