Basic NeuroscienceLocal landmark alignment for high-resolution fMRI group studies: Toward a fine cortical investigation of hand movements in human

- We propose the combination of high-resolution fMRI with non-linear registration technique involving explicit anatomical constraint for individual cortex region alignment.
- Precise local anatomical landmark alignment improves functional cluster detection and localization at group level.
- The quality of the registration obtained is assessed by both structural and functional indexes.

Converging evidence conclusively demonstrates the robust relationship between anatomical landmarks and underlying functional organization in primary cortical regions. In consequence, a precise alignment across subjects of such specific individual landmarks should improve the overlap of the corresponding functional areas and thus the detection of active clusters at the group level. In an effort to define a dedicated processing pipeline for a fine non-invasive exploration of the motor cortex in human, we evaluated four recent non-linear registration methods based on anatomical and functional indexes. We used high-resolution functional MRI data to finely reveal the impact of the registration on the cortical assignment of the detected clusters. Our results first demonstrate that the quality of registration strongly affects the statistical significance and the assignment of activated clusters to specific anatomical regions, here in the primary motor area. Our results also illustrate the bias induced by the chosen reference template on the detected clusters. The analysis of the Jacobian of the deformation field informs us about how each method deforms the anatomical structures and functional maps. The methodology we propose, combining high resolution fMRI and non-linear registration method, allows a robust non-invasive exploration of the motor cortex.