Improving laminar fMRI specificity by reducing macrovascular bias caused by respiration effects

Motivation: Although fMRI has achieved sub-millimeter spatial resolution especially with ultra-high field (≥7T) scanners, its spatial specificity has not kept pace. Goal(s): This study aims to map and validate the influences of natural respiratory variations on fMRI signals and use it to improve laminar fMRI specificity. Approach: We compare the influences of natural respiratory variations with the patterns induced by deep breath and breath hold tasks and probe their spatial correlation with vascular density. Results: This respiratory variation revealed information can be used to remove macrovascular-dominated voxels, thereby enhance laminar fMRI specificity. Impact: We highlight the significance of natural respiratory variations for improving laminar fMRI specificity. By understanding these variations and their link with vascular density, we can better identify and exclude macrovascular-dominated voxels, marking a notable advancement in high-resolution fMRI specificity.