Laminar fMRI of the human hippocampus: Accounting for physiological fluctuations and vasculature

Motivation: Laminar fMRI of the human hippocampus is challenging and not easy to interpret due to differences in the direction of venous drainage. Goal(s): Acquire robust and reproducible single-subject laminar fMRI responses using GRE-BOLD. Approach: An autobiographical memory task was used at 7 T to elicit hippocampal activation in two subjects each scanned twice. We quantified subregion-specific cortical depth-dependent activation after accounting for physiological signal fluctuations. Results: We show that laminar profiles differ between subjects but are to a high degree reproducible within subjects and that these profiles were consistent with previous findings at lower spatial resolution. Impact: Our results show that for laminar fMRI of deeper brain areas, physiological fluctuations need to be corrected to obtain reproducible data. The consistent difference between subjects indicate that subject-specific vasculature needs to be considered.