Miniscope in vivo imaging of cumulative traumatic brain injury

项目总结/摘要 在美国，每年有数百万人遭受创伤性脑损伤（TBI）， 医疗保健和社会成本每年超过450亿美元。轻度TBI（mTBI）占75%以上， 所有TBI，许多人持续一个以上。mTBI患者报告脑震荡后综合征（PCS） 包括睡眠障碍（失眠，白天嗜睡），躯体症状（头晕，头痛， 视力模糊），认知问题（记忆，执行功能），和情绪问题（焦虑，抑郁， 易激惹、抑制解除）。对于许多人来说，PCS是短暂的，仍然有10-25%的人报告持续的PCS症状。的 mTBI后神秘的PCS症状表现和持续性促使研究动态反应 将急性神经生理学与行为功能联系起来。调查小组在体内提炼了 评价脑血流量（CBF）和血液的微型显微镜（微型镜）成像方法 脑屏障（BBB）的通透性在不受限制的，行为小鼠。新的初步数据利用了 微型摄像头头帽导致撞击加速度（重量下降）闭合性头部损伤。推动这一提议的数据 显示在视野内的实质中荧光葡聚糖的立即积累。强度 这种方法消除了长时间成像过程中的麻醉， 限制，并锁定到基板上，用于单通道、宽视野、荧光的重复成像。第一 随着时间的推移，TBI对神经生理学（CBF，BBB渗透性，睡眠）的累积影响可以回归到 神经行为障碍本提案检验的假设是， mTBI对CBF和BBB渗透性的影响促进创伤后睡眠并预测神经损伤。 准备雄性和雌性小鼠用于通过颅窗和附接的基板进行微型镜成像。 底板头帽在闭头冲击加速度TBI中代替头盔。15秒的过渡， 微型内窥镜用腹膜内葡聚糖（40-2000 kDa）在血管系统中显示CBF和BBB渗透性， 薄壁组织。mTBI的累积效应通过每天两次、每天 或者一周内每隔一天目标1监测不同时间间隔的mTBI对 脑血流与创伤后睡眠和亚急性行为表现的关系目标2量化了 葡聚糖外渗与创伤后睡眠和亚急性神经功能表现。神经功能结局 包括焦虑（旷场）、空间记忆（新物体位置）和躯体感觉疼痛（机械性 痛觉过敏）。每天两次损伤可能显示CBF、BBB渗透性和睡眠效应的时间总和， 在两次受伤之间的恢复时间较长。微型显微镜成像与 闭合性颅脑损伤可以推动未来对TBI的生理扰动和临床管理的研究。

Project Summary/Abstract In the United States, millions of people sustain a traumatic brain injury (TBI) each year carrying individual, healthcare, and societal costs greater than $45 billion annually. Mild TBI (mTBI) accounts for more than 75% of all TBIs, with many individuals sustaining more than one. mTBI patients report post-concussion syndrome (PCS) symptoms that include sleep disorders (insomnia, daytime sleepiness), somatic symptoms (dizziness, headache, blurred vision), cognitive complaints (memory, executive function), and emotional problems (anxiety, depression, irritability, disinhibition). For many, PCS is transient, and still 10-25% report persistent PCS symptoms. The enigmatic PCS symptom presentation and persistence after mTBI urges investigation into dynamic responses in the brain that tie acute neurophysiology to behavioral function. The investigative team has refined in vivo imaging methods of miniaturized microscopes (miniscopes) to evaluate cerebral blood flow (CBF) and blood brain barrier (BBB) permeability in the unrestrained, behaving mouse. New preliminary data leverage the miniscope headcap to induce impact acceleration (weight drop) closed head injury. The data driving this proposal show immediate accumulation of fluorescent dextrans in the parenchyma within the field of view. The strength of this approach eliminates anesthesia during long-duration imaging, permits naturalistic behavior without head restraint, and locks into a baseplate for repeated imaging of single channel, wide-field, fluorescence. For the first time, the cumulative effects of TBI on neurophysiology (CBF, BBB permeability, sleep) can be regressed toward neurobehavioral impairments. The present proposal tests the hypothesis that the cumulative effects of mTBI on CBF and BBB permeability promote post-traumatic sleep and predict neurological impairments. Male and female mice are prepared for miniscope imaging through a cranial window and attached baseplate. The baseplate headcap substitutes for a helmet in closed-head impact acceleration TBI. With a 15 sec transition, miniscopes visualize CBF and BBB permeability with intraperitoneal dextrans (40-2000 kDa) in vasculature and parenchyma, respectively. The cumulative effects of mTBI are assessed with impacts delivered twice daily, daily, or every other day for a week. Aim 1 monitors the cumulative effects of mTBI with varying temporal spacing on CBF concurrent with post-traumatic sleep and subacute behavioral performance. Aim 2 quantifies the extent of dextran extravasation with post-traumatic sleep and subacute neurological performance. Neurological outcomes include anxiety (open field), spatial memory (novel object location), and somatosensory pain (mechanical hyperalgesia). Twice daily injuries likely show temporal summation of CBF, BBB permeability, and sleep effects, which are recovered with longer recovery times between injuries. The integration of miniscope imaging and closed head injury can propel future studies on physiological perturbations and clinical management of TBI.