DOI: 10.5061/dryad.mc7pd
title: Data from: Task-related effective connectivity reveals that the cortical rich club gates cortex-wide communication

description: Higher cognition may require the globally coordinated integration of
 specialized brain regions into functional networks. A collection of
 structural cortical hubs—referred to as the rich club—has been
 hypothesized to support task-specific functional integration. In the
 present paper, we use a whole-cortex model to estimate directed
 interactions between 68 cortical regions from functional magnetic
 resonance imaging activity for four different tasks (reflecting different
 cognitive domains) and resting state. We analyze the state-dependent input
 and output effective connectivity (EC) of the structural rich club and
 relate these to whole-cortex dynamics and network reconfigurations. We
 find that the cortical rich club exhibits an increase in outgoing EC
 during task performance as compared with rest while incoming connectivity
 remains constant. Increased outgoing connectivity targets a sparse set of
 peripheral regions with specific regions strongly overlapping between
 tasks. At the same time, community detection analyses reveal massive
 reorganizations of interactions among peripheral regions, including those
 serving as target of increased rich club output. This suggests that while
 peripheral regions may play a role in several tasks, their concrete
 interplay might nonetheless be task-specific. Furthermore, we observe that
 whole-cortex dynamics are faster during task as compared with rest. The
 decoupling effects usually accompanying faster dynamics appear to be
 counteracted by the increased rich club outgoing EC. Together our findings
 speak to a gating mechanism of the rich club that supports fast-paced
 information exchange among relevant peripheral regions in a task-specific
 and goal-directed fashion, while constantly listening to the whole
 network.
description: DATA_TASK_3DMOV_HP_CSF_WDBriefly, data comes from five functional runs consisting of a resting-state measurement (eyes closed), four individual task measurements including a visual n-back (n=2) task (Kirchner, 1958), the Eriksen flanker task (Eriksen & Eriksen, 1974), a mental rotation task (Shepard & Metzler, 1971), and a verbal odd-man-out task (Flowers & Robertson, 1985). All runs comprise 192 data points with tasks being continuously performed during this period. For the n-back and flanker task, stimuli were presented at a rate of 0.5 Hz; for the mental rotation and odd-man out tasks they were presented at a rate of 0.25 Hz. Task sequence was counterbalanced across participants with the exception that the resting state functional run was always acquired first to prevent carry-over effects (Grigg & Grady, 2010). The data were acquired using a 3 Tesla Siemens Prisma Fit (upgraded Tim Trio) scanner and a 64-channel head coil. Initial preprocessing was performed using BrainVoyager QX (v2.6; Brain Innovation, Maastricht, the Netherlands). This includes slice scan time correction, 3D-motion correction, high-pass filtering with a frequency cutoff of .01 Hz, and registration of functional and anatomical images. Subsequently, using MATLAB (2013a, The MathWorks,Natick, MA), signals were cleaned by performing wavelet despiking (Patel & Bullmore, 2015) and regressing out a global noise signal given by the first principal component of signals observed within the cerebrospinal fluid of the ventricles. Next, voxels were uniquely assigned to one of the 68 cortical ROIs specified by the DK atlas and an average BOLD time-series was computed for each region as the mean time-series over all voxels of that region.