Search bioRxiv⌕ Search

Biology subjects

Curcic, V.

Publications and source records attributed to Curcic, V..

2 recordsLinked to original sources

High-Resolution 3D Mapping of Human Cortical Vasculature

A quantitative description of the three-dimensional organization of the human cortical vasculature at micron scale is critical for understanding the influence of the vascular architecture on cerebral blood flow, neurovascular coupling, neurological disease, and human neuroimaging signals. However, high-resolution volumetric vascular data from human cortex are scarce, as the acquisition relies on postmortem microscopy, and tissue-clearing and whole-mount immunolabeling approaches developed for rodent tissues are less effective in heavily crosslinked, pigment rich fixed human cortex. Here we introduce h-iDISCO+, a workflow that enables whole-mount immunolabeling and high-resolution light-sheet imaging of arteries, capillaries, and veins in long-term formalin fixed human brain tissue. By integrating extended oxidative and photobleaching prior to tissue staining, we achieve uniform sample transparency and full-depth antibody penetration. Applying this workflow to tissue samples from human primary visual cortex, we quantified vessel geometrical properties and vascular density across cortical depth. This approach allows quantitative reconstruction of human cortical vascular networks at micron resolution, enabling volumetric datasets of the human cortical vasculature that were previously unavailable.

neuroscience↗

On the influence of the vascular architecture on Gradient Echo and Spin Echo BOLD fMRI signals across cortical depth: a simulation approach based on realistic 3D vascular networks

GE-BOLD contrast stands out as the predominant technique in functional MRI experiments for its high sensitivity and straightforward implementation. GE-BOLD exhibits rather similar sensitivity to vessels independent of their size at submillimeter resolution studies like those examining cortical columns and laminae. However, the presence of nonspecific macrovascular contributions poses a challenge to accurately isolate neuronal activity. SE-BOLD increases specificity towards small vessels, thereby enhancing its specificity to neuronal activity, due to the effective suppression of extravascular contributions caused by macrovessels with its refocusing pulse. However, even SE-BOLD measurements may not completely remove these macrovascular contributions. By simulating hemodynamic signals across cortical depth, we gain insights into vascular contributions to the laminar BOLD signal. In this study, we employed four realistic 3D vascular models to simulate oxygen saturation states in various vascular compartments, aiming to characterize both intravascular and extravascular contributions to GE and SE signals, and corresponding BOLD signal changes, across cortical depth at 7T. Simulations suggest that SE-BOLD cannot completely reduce the macrovascular contribution near the pial surface. Simulations also show that both the specificity and signal amplitude of BOLD signals at 7T depend on the spatial arrangement of large vessels throughout cortical depth and on the pial surface.

neuroscience↗