Biology subjects

Bertolo, A.

Publications and source records attributed to Bertolo, A..

3 recordsLinked to original sources

bioRxiv2024

Transcranial Brain-Wide Functional Ultrasound and Ultrasound Localization Microscopy in Mice using Multilinear Probes

Functional ultrasound imaging (fUS) and ultrasound localization microscopy (ULM) are advanced ultrasound imaging modalities for assessing both functional and anatomical characteristics of the brain. However, the application of these techniques at a whole-brain scale has been limited by technological challenges. While conventional linear acoustic probes provide a narrow 2D field of view and matrix probes lack sufficient sensitivity for 3D transcranial fUS, multilinear probes have been developed to combine high sensitivity to blood flow with fast 3D acquisitions. In this study, we present a novel approach the combined implementation of transcranial whole-brain fUS and ULM in mice using a motorized multilinear probe. This technique provides high-resolution, non-invasive imaging of neurovascular dynamics across the entire brain. Our findings reveal a significant correlation between absolute cerebral blood volume ({Delta}CBV) increases and microbubble velocity, indicating vessel-level dependency of the evoked response. However, the lack of correlation with relative CBV (rCBV) suggests that fUS cannot distinguish functional responses alterations across different arterial vascular compartments. This methodology holds promise for advancing our understanding of neurovascular coupling and could be applied in brain disease diagnostics and therapeutic monitoring.

neuroscience↗

bioRxiv2023

Leptomeningeal collaterals regulate reperfusion in ischemic stroke

Recanalization is the mainstay of ischemic stroke treatment. However, even with timely clot removal, many stroke patients recover poorly. Leptomeningeal collaterals (LMCs) are pial anastomotic vessels with yet unknown functions. Utilizing a thrombin-based mouse model of stroke and the gold standard fibrinolytic treatment rt-PA, we here show that LMCs play a critical role in preserving vascular function in ischemic territories. We applied laser speckle contrast imaging, ultrafast ultrasound, and two-photon microscopy, to show that after thrombolysis, LMCs allow for gradual reperfusion resulting in small infarcts. On the contrary, in mice with poor LMCs, distal segments of recanalized arteries collapse and deleterious hyperemia causes hemorrhage and mortality. Accordingly, in stroke patients with poor collaterals undergoing thrombectomy, rapid reperfusion resulted in hemorrhagic transformation and unfavorable recovery. Thus, we identify LMCs as key components regulating reperfusion after stroke. Future therapeutic interventions should aim to enhance collateral function, allowing for gradual reperfusion of ischemic tissues after stroke.

neuroscience↗

bioRxiv2022

Specific and non-uniform brain states during cold perception in mice

The quest to decode the complex supraspinal mechanisms that integrate cutaneous thermal information in the central system is still ongoing. The dorsal horn of the spinal cord is the first hub that encodes thermal input which is then transmitted to brain regions via the spinothalamic and thalamo-cortical pathways. So far, our knowledge about the strength of the interplay between the brain regions during thermal processing is limited. To address this question, we imaged the brains of awake and freely-moving mice using Functional Ultrasound imaging during plantar exposure to constant and varying temperatures. Our study, a synchronous large field investigation of mice brains reveals for the first time the brain states and the specific dynamic interplay between key regions involved in thermal processing. Our study reveals: i) a dichotomy in the response of the somato-motor-cingulate cortices and the hypothalamus, which was never described before, due to the lack of appropriate tools to study such regions with both good spatial and temporal resolutions. ii) We infer that cingulate areas may be involved in the affective responses to temperature changes. iii) Colder temperatures (ramped down) reinforces the disconnection between the somato-motor-cingulate and hypothalamus networks. iv) Finally, we also confirm the existence in the mouse brain of a dynamic brain mode characterized by low cognitive strength, described previously only in non-human primates and humans. The present study points towards the existence of a common hub between somato-motor and cingulate regions, whereas hypothalamus functions are related to a secondary network.

neuroscience↗