title: Very large fMRI study using the IMAGEN database: sensitivity-specificity and population effect modeling in relation to the underlying anatomy.
abstract: In this paper we investigate the use of classical fMRI Random Effect (RFX) group statistics when analyzing a very large cohort and the possible improvement brought from anatomical information. Using 1326 subjects from the IMAGEN study, we first give a global picture of the evolution of the group effect t-value from a simple face-watching contrast with increasing cohort size. We obtain a wide activated pattern, far from being limited to the reasonably expected brain areas, illustrating the difference between statistical significance and practical significance. This motivates us to inject tissue-probability information into the group estimation, we model the BOLD contrast using a matter-weighted mixture of Gaussians and compare it to the common, single-Gaussian model. In both cases, the model parameters are estimated per-voxel for one subgroup, and the likelihood of both models is computed on a second, separate subgroup to reflect model generalization capacity. Various group sizes are tested, and significance is asserted using a 10-fold cross-validation scheme. We conclude that adding matter information consistently improves the quantitative analysis of BOLD responses in some areas of the brain, particularly those where accurate inter-subject registration remains challenging.
authors.affiliation: Neurospin, Commissariat à l'Energie Atomique, Gif-sur-Yvette, France. benjamin.thyreau@gmail.com
authors.forename: Benjamin
authors.initials: B
authors.lastname: Thyreau
authors.forename: Yannick
authors.initials: Y
authors.lastname: Schwartz
authors.forename: Bertrand
authors.initials: B
authors.lastname: Thirion
authors.forename: Vincent
authors.initials: V
authors.lastname: Frouin
authors.forename: Eva
authors.initials: E
authors.lastname: Loth
authors.forename: Sabine
authors.initials: S
authors.lastname: Vollstädt-Klein
authors.forename: Tomas
authors.initials: T
authors.lastname: Paus
authors.forename: Eric
authors.initials: E
authors.lastname: Artiges
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Conrod
authors.forename: Gunter
authors.initials: G
authors.lastname: Schumann
authors.forename: Robert
authors.initials: R
authors.lastname: Whelan
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Poline
mesh_terms: D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D001931:Brain Mapping / Q000379:methods*; D016208:Databases, Factual; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008959:Models, Neurological; D015233:Models, Statistical; D016011:Normal Distribution; D010100:Oxygen / Q000097:blood; D011153:Population; D015203:Reproducibility of Results
chemical_list: D010100:Oxygen