ESSEC working Group on risk

L'Institut des Actuaires s'associe au Working Group on Risk de l'ESSEC-CREAR pour sa prochaine conférence sur le thème : " A Bayesian general Linear Modeling Approach to Cortical Surface fMRI Data Analysis " par le David BOLIN de University of Gothhenburg et Chalmers Univertisy – (Sweden)

Abstract: Cortical surface fMRI (cs-fMRI) has recently grown in popularity versus traditional volumetric fMRI, as it allows for more meaningful spatial smoothing and is more compatible with the common assumptions of isotropy and stationarity in Bayesian spatial models. However, as no Bayesian spatial model has been proposed for cs-fMRI data, most analyses continue to employ the classical, voxel-wise general linear model (GLM). Here, we propose a Bayesian GLM for cs-fMRI, which employs a class of spatial processes based on stochastic partial differential equations to model latent activation fields. Bayesian inference is performed using integrated nested Laplacian approximations (INLA), which is a computationally efficient alternative to Markov Chain Monte Carlo. To identify regions of activation, we propose an excursions set method based on the joint posterior distribution of the latent fields, which eliminates the need for multiple comparisons correction. Finally, we address a gap in the existing literature by proposing a Bayesian approach for multi-subject analysis. The methods are validated and compared to the classical GLM through simulation studies and a motor task fMRI study from the Human Connectome Project. The proposed Bayesian approach results in smoother activation estimates, more accurate false positive control, and increased power to detect truly active regions.

 A l'initiative du Centre de Recherche sur le Risque de l'ESSEC – CREAR, avec le soutien de l'Institut des Actuaires, du LabEx MME-DII, du Ceressec et du bureau Banque-Finance-Assurance de la Société Française de Statistique, le WG Risk organise environ deux fois par mois des conférences sur le thème des risques. Réunissant professionnels, universitaires et étudiants, et coordonnées par Marie Kratz, Professeure à l'ESSEC, les conférences données par des professionnels ou des académiques sur des sujets d'actualité peuvent être en français ou en anglais. Retrouvez toutes les informations pratiques et les précédentes conférences sur le site de CREAR-ESSEC : http://crear.essec.edu/working-group-on-risk