Motion or activity: their role in intra- and inter-subject variation in fMRI

• Published in: NeuroImage (Orlando, Fla.) Vol. 26; no. 3; pp. 960 - 964
• Main Authors: Lund, Torben E., Nørgaard, Minna D., Rostrup, Egill, Rowe, James B., Paulson, Olaf B.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2005; Elsevier Limited
• Subjects: Adult; Brain - physiology; Brain Mapping - methods; Data analysis; Data Interpretation, Statistical; fMRI; Humans; Inter-session variability; Linear Models; Magnetic Resonance Imaging - statistics & numerical data; Models, Neurological; Movement - physiology; Movement artefacts; Psychomotor Performance - physiology; Reproducibility of Results; Semantics; Speech - physiology; Studies; fMRI; Movement artefacts; Inter-session variability
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2005.02.021

Functional MRI (fMRI) carries the potential for non-invasive measurements of brain activity. Typically, what are referred to as activation images are actually thresholded statistical parametric maps. These maps possess large inter-session variability. This is especially problematic when applying fMRI to pre-surgical planning because of a higher requirement for intra-subject precision. The purpose of this study was to investigate the impact of residual movement artefacts on intra-subject and inter-subject variability in the observed fMRI activation. Ten subjects were examined using three different word-generation tasks. Two of the subjects were examined 10 times on 10 different days using the same paradigms. We systematically investigated one approach of correcting for residual movement effects: the inclusion of regressors describing movement-related effects in the design matrix of a General Linear Model (GLM). The data were analysed with and without modeling the residual movement artefacts and the impact on inter-session variance was assessed using F-contrasts. Inclusion of motion parameters in the analysis significantly reduced both the intra-subject as well as the inter-subject-variance.