Functional imaging of hippocampal layers using VASO on the Next Generation (NexGen) 7T

Motivation: Imaging hippocampal activity is challenging due to its anatomical location deep in the brain, high physiological noise, and sensitivity to individual vasculature. Goal(s): Optimize the VASO imaging sequence on the NexGen 7T scanner at sub-millimeter resolution to assess layer-specific VASO patterns using an established autobiographical memory task. Approach: Measure activation of the right hippocampus in three subjects, and compare layer profiles based on VASO and BOLD from the same acquisition, per hippocampal subfield. Results: Hippocampal VASO activation was observed in all subjects. Depth-related differences between VASO and BOLD were in line with lesser venous bias in VASO. Impact: Hippocampal fMRI using VASO contrast allows mapping layer function with high accuracy, made possible by optimization for the NexGen 7T scanner. Spatial accuracy and venous biases are a central concern for studies developing mechanistic models for hippocampal circuits.