55: A Spatially-aware Hyperalignment Method Using a Penalized Orthogonal Procrustes Approach

Music City Center 

Functional magnetic resonance imaging (fMRI) plays a crucial role in investigating the human brain's responses to stimuli. Addressing a key challenge that individuals differ in their brain's underlying functional topography, the Hyperalignment method aligns functional brain representations across individuals by projecting neural responses into a shared high-dimensional space. Through the orthogonal Procrustes transformation, one can search on the Stiefel manifold and determine the optimal rotation for aligning images to a common template. However, unconstrained optimization disregards natural topological structure and may result in highly variable loadings for adjacent brain locations in the estimated projection, potentially causing location flips for distant voxels in extreme cases. To address this issue, we propose a spatially-aware Hyperalignment model that incorporates penalties to encourage smoothness in the projection. By constraining nearby voxel loadings, our approach restricts the search space on the Stiefel manifold leading to a more spatially coherent alignment. We illustrate the benefits of the methods through simulations and application to data from fMRI experiments.

fMRI

Hyperalignment

Penalized Procrustes

Spatial Regularization 

Section on Statistics in Imaging