Targeting specific cortical microcircuit components to enhance functional recover

描述(申请人提供)：在美国2005年至2050年期间估计的2.2万亿美元中风相关成本中，有很大一部分与脑损伤后恢复期的护理成本有关，而这反过来又与残疾水平高度相关。这些数字表明改善中风后神经康复的紧迫性，特别是因为目前还没有药物可用，也没有任何药物正在研制中，以促进中风后的功能恢复。直到最近，很少有研究关注卒中后功能恢复的基本机制和潜在的改善。我们实验室以前的发现，以及一些有希望的人类数据表明，兴奋性/抑制性皮质环路之间的失衡是中风后功能恢复的主要障碍。我们将使用中风的小鼠模型来研究如何改善损伤后脑刺激的结果。将使用一种新的中风模型在小鼠的运动皮质中诱导光血栓形成中风，该模型是为在清醒的自由运动动物中诱导局灶性缺血而开发的。我们将测试这一假设，即对受影响的皮质微回路的高度特异性成分的调制将在中风后的功能恢复方面提供最佳结果。四个不同的转基因小鼠品系将被用来对梗塞周围区域或对侧大脑半球相当的皮质区域的兴奋性和抑制性皮质微回路进行特定的光遗传操作。1)在梗死区刺激皮质锥体细胞，以测试兴奋回路的刺激效果；2)在梗死区抑制GABA能细胞的活动，以减少我们实验室先前所观察到的卒中后增强的抑制作用，以阻断功能恢复的途径；3)刺激梗死区周围的胶质细胞，以测试胶质细胞活性受损和继发性GABA摄取减少是否有助于所观察到的抑制作用的增强和随之而来的延迟的功能恢复；4)在梗塞的对侧，GABA能细胞将被刺激，以抑制健康运动皮质的输出，这可能起到降低患侧活动的作用。在卒中诱导后的5天内，每天进行1小时的光刺激，基于非侵入性的、但非特异性的人类大脑模拟方案。除了更传统的小鼠功能运动恢复测量方法外，我们还将使用一种新的自动测量方法来测量小鼠在空气支持的球体上的运动，这种测量方法可以比以前使用的运动恢复测量方法进行更好的量化。通过在卒中诱导、刺激治疗和结果度量方面引入新的方法，该项目解决了与美国和世界范围内卒中的巨大经济和健康负担相关的科学问题。该项目还将确定在临床实践中促进康复的具体目标系统，以实现中风患者更健康的生活和更早的功能恢复。 公共卫生相关性：中风是全球慢性残疾的主要原因，据估计，从2005年到2050年，它给美国造成了2.2万亿美元的损失。这笔钱的很大一部分 与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，特别是在没有药物可用的情况下，也没有任何药物正在筹备中以促进中风后的功能恢复。在人类身上进行的促进中风后恢复的实验方法包括无创和高度非特异性的大脑模拟。我们将使用中风的小鼠模型来研究如何改善中风后脑刺激的结果。我们将测试光刺激(或抑制)受损皮质微回路中特定元素的活动，以找出对中风恢复最有效的干预措施。通过在中风研究中引入新的方法，该项目将解决与美国和世界范围内中风的巨大健康和经济负担有关的科学问题。该项目将确定未来可以转化为临床实践的特定目标系统，以实现中风患者更好、更快的功能恢复。

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. PUBLIC HEALTH RELEVANCE: Stroke is the major cause of chronic disability worldwide and it is estimated to cost the U.S. $2.2 trillion between 2005 to 2050. A large portion of this amount pertains to the cost of care during the recovery period, which in turn is highly correlated with th 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. Experimental approaches in humans geared to facilitate post-stroke recovery include non-invasive and highly non-specific brain simulation. We will use a mouse model of stroke to examine how we can improve on the outcome of brain stimulation after stroke. Optical stimulation (or dampening) of the activities of specific elements of injured cortical microcircuits will be tested to find out the most effective intervention for stroke recovery. By introducing novel approaches in stroke research, the project will addresses scientific questions related to the enormous health and economical burdens of stroke in both the US and worldwide. The project will identify specific target systems that can be translated in the future into clinical practice, to accomplish a better and speedier recovery of function in stroke victims.