Targeting specific cortical microcircuit components to enhance functional recover

描述（由申请人提供）：2005 年至 2050 年间，美国估计的 2.2 万亿美元中风相关费用，其中很大一部分与脑外伤后恢复期的护理费用有关，而这又与残疾程度高度相关。这些数字表明改善中风后神经康复的紧迫性，特别是因为没有可用的药物，也没有任何药物正在研发中，以促进中风后的功能恢复。直到最近，只有少数研究关注中风后功能恢复的基本机制和潜在改善。我们实验室之前的研究结果以及一些有关中风康复患者非侵入性脑刺激的有希望的人体数据表明，兴奋性/抑制性皮层回路之间的不平衡是中风后功能恢复的主要障碍。我们将使用中风小鼠模型来研究如何改善损伤后大脑刺激的结果。光血栓性中风将在小鼠的运动皮层中诱导，使用一种新的中风模型，该模型是为在清醒的自由活动的动物中诱导局灶性缺血而开发的。我们将测试以下假设：对受影响的皮质微电路的高度特异性成分进行调节将为中风后的功能恢复提供最佳结果。四种不同的转基因小鼠品系将用于对梗塞周围区域或对侧半球的等效皮质区域的兴奋性和抑制性皮质微电路进行特定的光遗传学操作。 1）刺激梗塞周围区皮质锥体细胞，测试同侧刺激兴奋性回路的效果； 2) 抑制性 GABA 能细胞的活性将在梗塞周围区域受到抑制，以减少中风后观察到的增强的抑制作用，我们的实验室之前表明，这会阻碍功能恢复的路径； 3) 刺激梗死周围的神经胶质细胞，以测试受损的神经胶质细胞活性和继发性减少的 GABA 摄取是否可能导致观察到的抑制增强和随后的功能恢复延迟； 4) 在梗塞的对侧，GABA能细胞将受到刺激，抑制健康运动皮层的输出，这可能会降低病变侧的活动。中风诱导后，将根据人类受试者非侵入性但非特异性的大脑模拟方案，每天进行 1 小时的光刺激，持续 5 天。除了更传统的小鼠功能性运动恢复测量之外，我们还将使用一种新颖的自动测量方法来测量小鼠在空气支撑球体上的运动，与以前使用的运动恢复测量相比，该测量可以得到更好的量化。通过引入中风诱导、刺激治疗和结果指标的新方法，该项目解决了与美国和全球中风巨大经济和健康负担相关的科学问题。该项目还将确定促进临床实践康复的具体目标系统，从而使中风患者过上更健康的生活并尽早恢复功能。

DESCRIPTION (provided by applicant): A large portion of the estimated $2.2 trillion stroke-related costs estimated in the U.S. between 2005 and 2050 pertains to the cost of care during the recovery period after the brain trauma, which in turn is highly correlated with the level of disability. These figures point to the urgency of improving post stroke neurorehabilitation, particularly since there are no drugs available, nor are there any in the pipeline, to facilitate functional recovery after stroke. Until recently, only few studies focused on the basic mechanisms and potential improvement of post stroke functional recovery. Previous findings from our laboratory, and some promising human data about non-invasive brain stimulation in recovering stroke patients, point to an imbalance between excitatory/inhibitory cortical circuits as a major obstacle in post stroke functional recovery. We will use a mouse model of stroke to examine how the outcome of brain stimulation after the injury can be improved. Photothrombotic stroke will be induced in the motor cortices of mice using a novel stroke model developed for focal ischemia induction in awake freely moving animals. We will test the hypothesis that the modulation of a highly specific component of the affected cortical microcircuits will provide the best outcome on functional recovery after stroke. Four different transgenic mouse lines will be used for specific optogenetic manipulations of excitatory and inhibitory cortical microcircuits in the peri-infarct region, or in the equivalent cortical area on the contralateral hemisphere. 1) Cortical pyramidal cells will be stimulated in the peri-infarct zone to test the effects of ipsilesonal stimulation of excitatory circuits; 2) The activity of inhibitory GABAergic cells will be suppresse in the peri-infarct zone to reduce the enhanced inhibition observed after stroke, previously shown by our lab to obstruct the path to functional recovery; 3) Peri-infarct glial cells will be stimulated to test whether impaired glial activity and a secondarily reduced GABA uptake may contribute to the observed enhancement in inhibition and the ensuing delayed functional recovery; 4) Contralateral to the infarct, GABAergic cells will be stimulated to dampen the output of the healthy motor cortex which may act to lower the activity of the lesioned side. Optical stimulation will be carried out for 5 days after stroke induction in daily 1-hour sessions, based o protocols of non-invasive, but non-specific brain simulation in human subjects. In addition to more traditional measures of functional motor recovery in mice, we will use a novel automated measurement of the mouse's movements on an air-supported sphere, which can be subjected to better quantification than previously used measures of motor recovery. By introducing novel approaches in stroke induction, stimulation therapy, and outcome metrics, the project addresses scientific questions related to the enormous economical and health burdens of stroke in both the U.S. and worldwide. The project will also identify specific target systems for promoting rehabilitation in the clinical practice, to result in a healthier life and an earlier functional reovery of stroke victims.