Denis Chaimow | Laminar fMRI in the human prefrontal cortex at 7T: A replication study of layer-dependent activity during working memory

High-resolution fMRI is a promising tool to study the cortical basis of cognitive processes non-invasively in human subjects. A recent study (Finn et al. 2019) demonstrated the ability of high-resolution fMRI in humans to measure layer specific effects in the prefrontal cortex. They used vascular space occupancy (VASO) fMRI to measure cortical layer specific cerebral blood volume (CBV) changes during different periods of a delayed-response task in the dorsolateral prefrontal cortex dlPFC. They found that superficial layers were more active during the delay period when working memory items needed to be manipulated (alphabetization of a random letter sequence) compared to mere maintenance (remembering of the original letter sequence). In contrast, deeper layers were more active during the response period. Given its importance for the field of cognitive neuroscience we aim at replicating this seminal study and evaluate the robustness of its results. Moreover, we want to confirm that the reported results are robust with respect to our specific slightly different experimental setup consisting of a different MRI scanner, different version, and parameters of the SS-SI-VASO pulse sequence and differences in institutional constraints like maximal duration of human participant sessions. Lastly, the study by Finn et al. 2019 relied, like most layer fMRI studies to date, on a substantial amount of semi-manual or manual analysis steps including their ROI definition, gray matter segmentation and layer definition. To test whether less manual intervention can lead to comparable results we will limit ourselves to a more automatic analysis approach.