Biology subjects

Bacskai, B.

Publications and source records attributed to Bacskai, B..

4 recordsLinked to original sources

bioRxiv2026

Vessel-Resolved Mapping of Perivascular Spaces Reveals Hierarchical Neurofluid Organization In Vivo

Perivascular spaces (PVS) are central to cerebrospinal fluid (CSF)-interstitial fluid (ISF) exchange in the brain, yet their brain-wide organization and in vivo accessibility remain poorly resolved due to limited spatial resolution and contrast specificity of existing imaging approaches. Prior gadolinium (Gd)-enhanced MRI studies demonstrate global tracer distribution but yield spatially diffuse signals that do not resolve PVS at the level of individual vessels. Here we introduce an ultra-high-resolution dual-contrast MRI framework that enables vessel-resolved mapping of PVS across the whole brain in vivo. This approach combines ultra-high-field imaging, an implantable radiofrequency coil for enhanced local sensitivity, and intraventricular Gd delivery to achieve sufficient contrast and spatial specificity for detecting vessel-associated perivascular signal. Using this framework, we show that PVS are hierarchically organized along vascular trees, extending from major surface arteries into deep cortical and subcortical regions. Signal patterns along arterial branches and junctions indicate that PVS follows vascular topology. Quantitative analysis reveals that only a subset of penetrating vessels ([~]6%) exhibits detectable PVS signal, indicating heterogeneous organization across vascular networks independent of vessel caliber. Widespread detection of PVS, including in the hippocampus, further demonstrates that ventricularly delivered tracers access a distributed, vessel-associated perivascular network in vivo. These results establish an anatomical framework for mapping perivascular transport pathways across the brain, bridging global tracer imaging with vessel-resolved organization, and enabling investigation of how vascular architecture and fluid dynamics shape CSF-ISF exchange.

neuroscience↗

bioRxiv2026

Amyloid plaques drive long-range circuit reorganization in a mouse model of Alzheimer's disease

Amyloid plaques are a pathological hallmark of Alzheimers disease, but how they drive widespread neuronal dysfunction remains unclear. While studies in anesthetized animals show that plaques drive local hyperactivity1,2, it is unknown how this pathology shapes functional hippocampal maps in freely behaving animals. We combined chronic 1-photon calcium imaging, local field potential recordings, and post hoc 2-photon plaque imaging in freely behaving APP/PS1 mice across behavior and sleep to correlate real-time hippocampal activity and place coding with precise plaque topography. Here we show that plaques exert nonlocal, long-range effects on hippocampal activity that depend on plaque size, laminar position, and the animals behavioral state. Place cells, which encode spatial position and are normally uniformly distributed, are preferentially enriched near plaques, revealing an aberrant reorganization of plaque-adjacent neurons into the hippocampal map of space. In longitudinal experiments, pre-existing place cell locations do not predict future plaque sites, whereas hyperactivity during slow-wave sleep weakly predicts future amyloid deposition. These findings identify a mechanism by which amyloid pathology reorganizes brain circuits, degrading the functional architecture of the hippocampus and contributing to widespread dysfunction and cognitive impairment in Alzheimers disease.

neuroscience↗

bioRxiv2024

Loss of spontaneous vasomotion precedes impaired cerebrovascular reactivity and microbleeds in a mouse model of cerebral amyloid angiopathy

BackgroundCerebral amyloid angiopathy (CAA) is a cerebral small vessel disease in which amyloid-{beta} accumulates in vessel walls. CAA is a leading cause of symptomatic lobar intracerebral hemorrhage and an important contributor to age-related cognitive decline. Recent work has suggested that vascular dysfunction may precede symptomatic stages of CAA, and that spontaneous slow oscillations in arteriolar diameter (termed vasomotion), important for amyloid-{beta} clearance, may be impaired in CAA. MethodsTo systematically study the progression of vascular dysfunction in CAA, we used the APP23 mouse model of amyloidosis, which is known to develop spontaneous cerebral microbleeds mimicking human CAA. Using in vivo 2-photon microscopy, we longitudinally imaged unanesthetized APP23 transgenic mice and wildtype littermates from 7 to 14 months of age, tracking amyloid-{beta} accumulation and vasomotion in individual pial arterioles over time. MRI was used in separate groups of 12-, 18-, and 24-month-old APP23 transgenic mice and wildtype littermates to detect microbleeds and to assess cerebral blood flow and cerebrovascular reactivity with pseudo-continuous arterial spin labeling. ResultsWe observed a significant decline in vasomotion with age in APP23 mice, while vasomotion remained unchanged in wildtype mice with age. This decline corresponded in timing to initial vascular amyloid-{beta} deposition ([~]8-10 months of age), although was more strongly correlated with age than with vascular amyloid-{beta} burden in individual arterioles. Declines in vasomotion preceded the development of MRI-visible microbleeds and the loss of smooth muscle actin in arterioles, both of which were observed in APP23 mice by 18 months of age. Additionally, evoked cerebrovascular reactivity was intact in APP23 mice at 12 months of age, but significantly lower in APP23 mice by 24 months of age. ConclusionsOur findings suggest that a decline in spontaneous vasomotion is an early, potentially pre-symptomatic, manifestation of CAA and vascular dysfunction, and a possible future treatment target.

neuroscience↗

bioRxiv2022

Real-time imaging of mitochondrial redox reveals increased mitochondrial oxidative stress associated with amyloid beta aggregates in vivo in a mouse model of Alzheimer's disease

BackgroundReactive oxidative stress is a critical player in the amyloid beta (A{beta}) toxicity that contributes to neurodegeneration in Alzheimers disease (AD). Mitochondrial damage, observed in AD, is one of the main sources of reactive oxygen species. Although A{beta} causes neuronal mitochondria-associated reactive oxidative stress in vitro, this has never been directly observed in the in vivo living brain. Here, we tested whether A{beta} plaques and soluble oligomers induce mitochondrial oxidative stress in surrounding neurons in vivo, and whether the neurotoxic effect can be abrogated using mitochondrial-targeted antioxidants. MethodsWe expressed a genetically encoded fluorescent ratiometric mitochondria-targeted reporter of oxidative stress in mouse models of the disease, and performed intravital multiphoton microscopy of neuronal mitochondria and A{beta} plaques. ResultsFor the first time, we demonstrated by direct observation exacerbated mitochondrial oxidative stress in neurons after both A{beta} plaque deposition and direct application of soluble oligomeric A{beta} onto the brain, and determined the most likely pathological sequence of events leading to oxidative stress in vivo. Oxidative stress could be inhibited by both blocking calcium influx into mitochondria and treating with the mitochondria-targeted antioxidant SS31. ConclusionsConsidering these results, mitochondria-targeted compounds hold promise as neuroprotective drugs for the prevention and/or treatment of AD.

neuroscience↗