A tutorial on group effective connectivity analysis, part 1: first level analysis with DCM for fMRI

TL;DR

This tutorial explains the principles, assumptions, and practical steps for applying DCM to fMRI data, focusing on first-level analysis and providing resources for reproducibility.

Contribution

It offers a detailed, accessible guide to DCM for fMRI, clarifying theoretical foundations and practical considerations for researchers.

Findings

Clarifies priors and assumptions in DCM for fMRI

Provides step-by-step instructions for first-level analysis

Includes reproducible analysis data and code

Abstract

Dynamic Causal Modelling (DCM) is the predominant method for inferring effective connectivity from neuroimaging data. In the 15 years since its introduction, the neural models and statistical routines in DCM have developed in parallel, driven by the needs of researchers in cognitive and clinical neuroscience. In this tutorial, we step through an exemplar fMRI analysis in detail, reviewing the current implementation of DCM and demonstrating recent developments in group-level connectivity analysis. In the first part of the tutorial (current paper), we focus on issues specific to DCM for fMRI, unpacking the relevant theory and highlighting practical considerations. In particular, we clarify the assumptions (i.e., priors) used in DCM for fMRI and how to interpret the model parameters. This tutorial is accompanied by all the necessary data and instructions to reproduce the analyses using the SPM software. In the second part (in a companion paper), we move from subject-level to group-level modelling using the Parametric Empirical Bayes framework, and illustrate how to test for commonalities and differences in effective connectivity across subjects, based on imaging data from any modality.