Optimized signal saturation for fast functional line-scanning of cortical layers

Layer-dependent fMRI is typically performed at sampling rates below 1 Hz and voxel sizes of 0.7-0.9 mm3 containing signal from multiple anatomical layers. Line-scanning can enhance spatial resolution to 0.2-0.4 mm while maintaining sub-second TR. It is therefore an ideal method to study temporal evolution of BOLD responses across cortical layers. However, current saturation schemes for human line-scanning suffer from broad saturation profiles that lead to signal contamination of BOLD responses from adjacent areas. We implemented line-scanning in humans with sharp line-profiles of 3 mm. Using this method, we show that cortical layers of M1 have unique BOLD time courses.