Triangulating a Cognitive Control Network Using Diffusion-Weighted Magnetic Resonance Imaging (MRI) and Functional MRI

TLDR

Stopping motor responses relies on the right inferior frontal cortex and a midbrain region corresponding to the subthalamic nucleus. The study tested whether the preSMA mediates conflict detection/resolution within a network linking the preSMA, IFC, and STN. Diffusion‑weighted imaging tractography mapped a white‑matter connection between IFC and STN, while fMRI during a conditional stop‑signal task examined behavioral and neural signatures of conflict‑induced slowing. Greater conflict‑induced slowing produced stronger activation of preSMA, IFC, and STN that matched the tractography‑predicted foci, confirming a right‑hemisphere three‑way functional–anatomical network capable of braking or stopping responses.

Abstract

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.