Biology subjects

Mihelic, S. A.

Publications and source records attributed to Mihelic, S. A..

3 recordsLinked to original sources

bioRxiv2023

Microvascular plasticity in stroke recovery: Longitudinal snapshots, network statistical analysis, and dynamics

This research article quantitatively investigates neuro-microvascular network remodeling dynamics following stroke using a novel in vivo two-photon angiography (cubic millimeter volume, weekly snapshots) and high throughput (thousands of connected capillaries) vascular vectorization method. The results suggest distinct temporal patterns of cere-brovascular plasticity, with acute remodeling peaking at one week post-stroke. The network architecture then gradually stabilizes, returning to a new steady state after four weeks. These findings align with previous literature on neuronal plasticity, highlighting the correlation between neuronal and neurovascular remodeling. Quantitative analysis of neurovascular networks using length- and strand-based statistical measures reveals intri-cate changes in network anatomy and topology. The distance and strand-length statistics show significant alterations, with a peak of plasticity observed at one week post-stroke, followed by a gradual return to baseline. The orientation statistic plasticity peaks at two weeks, gradually approaching the (conserved across subjects) stroke signature. The underlying mechanism of the vascular response (angiogenesis vs. tissue deformation), however, is yet unelucidated, requiring network registration advancements. Overall, the combination of two-photon angiography, vectorization, reconstruction/visualization, and statistical analysis enables both qualitative and quantitative assessments of neu-rovascular remodeling dynamics, demonstrating an impactful method for investigating neuro-microvascular network disorders and the therapeutic modes of action thereof. Understanding the timing and nature of neurovascular remodeling allows for optimized interventions, including personalized medicine for stroke rehabilitation. Additionally, the evaluation of pharmaceutical interventions using these tools may facilitate targeted drug development. Furthermore, neurovascular coupling dynamics have implications for neurodegenerative diseases, brain aging, and the field of brain-computer interfaces.

neuroscience↗

bioRxiv2021

An evaluation of resonant scanning as a high-speed imaging technique for two-photon imaging of cortical vasculature

We demonstrate a simple, low-cost two-photon microscope design with both galvo-galvo and resonant-galvo scanning capabilities. We quantify and compare the signal-to-noise ratios and imaging speeds of the galvo-galvo and resonant-galvo scanning modes when used for murine neurovascular imaging. The two scanning modes perform as expected under shot-noise limited detection and are found to achieve comparable signal-to-noise ratios. Resonant-galvo scanning is capable of reaching desired signal-to-noise ratios using less acquisition time when higher excitation power can be used. Given equal excitation power and total pixel dwell time between the two methods, galvo-galvo scanning outperforms resonant-galvo scanning in image quality when detection deviates from being shot-noise limited.

neuroscience↗

bioRxiv2020

Establishing the Effect of Vascular Structure on Laser Speckle Contrast Imagining

Laser Speckle Contrast Imaging (LSCI) is a powerful tool for non-invasive, real-time imaging of blood flow in tissue. However, the effect of tissue geometry on the form of the electric field autocorrelation function and speckle contrast values is yet to be investigated. In this paper, we present an ultrafast forward model for simulating a speckle contrast image with the ability to rapidly update the image for a desired illumination pattern and flow perturbation. We demonstrate the first simulated speckle contrast image and compare it against experimental results. We simulate three mouse-specific cerebral cortex decorrelation time images and implement three different schemes for analyzing the effects of homogenization of vascular structure on correlation decay times. Our results indicate that dissolving structure and assuming homogeneous geometry creates up to ∼ 10x shift in the correlation function decay times and alters its form compared with the case for which the exact geometry is simulated. These effects are more pronounced for point illumination and detection imaging schemes. Further analysis indicates that correlated multiple scattering events, on average, account for 50% of all dynamic scattering events for a detector over a vessel region and 31% that of a detector over parenchyma region, highlighting the significance of accurate modeling of the three-dimensional vascular geometry for accurate blood flow estimates.Competing Interest StatementThe authors have declared no competing interest.View Full Text

bioengineering↗