Uncovering communities of pipelines in the task-fMRI analytical space

TL;DR

It is shown that there are subsets of pipelines that give similar results, especially those sharing specific parameters (e.g. number of motion regressors, software packages, etc.).

Abstract

Analytical workflows in functional magnetic resonance imaging are highly flexible with limited best practices as to how to choose a pipeline. While it has been shown that the use of different pipelines might lead to different results, there is still a lack of understanding of the factors that drive these differences and of the stability of these differences across contexts. We use community detection algorithms to explore the pipeline space and assess the stability of pipeline relationships across different contexts. We show that there are subsets of pipelines that give similar results, especially those sharing specific parameters (e.g. number of motion regressors, software packages, etc.). Those pipeline-to-pipeline patterns are stable across groups of participants but not across different tasks. By visualizing the differences between communities, we show that the pipeline space is mainly driven by the size of the activation area in the brain and the scale of statistic values in statistic maps.

Figures (6)

• Figure 1: Workflow of community detection in the pipeline space across different groups of participants and contrasts.
• Figure 2: Adjacency matrix representing the number of times each pair pipelines belong to the same community across different group-level statistic maps of the contrast right hand.
• Figure 3: Mean statistic map across groups of subjects for a representative pipeline of each community for the contrast right-hand. Unthresholded maps (upper) and thresholded maps (lower) with FDR-corrected $p < 0.05$.
• Figure 4: Adjacency matrix representing the number of times each pair pipelines belong to the same community across different group-level statistic maps of the contrast right foot.
• Figure 5: Adjacency matrix representing the mean correlations across groups between statistic maps of each pair pipelines for the contrast right foot. Correlations between statistic maps of pipelines located in community 1 and community 2 are shown in a yellow box. Correlations between statistic maps of pairs pipelines located in community 3 that have a low number of co-occurence in the same community are shown in a blue box.