Comparison of Layer-Specific BOLD Responses Across Cortical Depths Using 7T Line-Scanning fMRI

Motivation: To understand the effects of vascular geometry and the layer-specific distributions of gradient-echo (GE) and spin-echo (SE) BOLD. Goal(s): To examine the GE and SE BOLD responses at different cortical layers in the somatosensory cortex. Approach: 1D line-scanning with a finger-tapping task was performed at a resolution of 0.6 x 4 x 4 mm³ to capture BOLD responses across 12 echo lines at four different depths from the pial surface in the somatosensory cortex. Results: Pure SE BOLD responses with low percentage changes were detected across all layers. The pial surface contributed a significantly greater GE BOLD response compared to the deeper layers. Impact: The percentage change of BOLD response depends greatly on both depth from the pial surface and TE. 1D line-scanning can play a crucial role in advancing mesoscopic fMRI resolution (e.g., layer-specific fMRI), potentially surpassing the conventional resolution of 0.8 mm