Optical Detection of the Pre-seizure State

描述（由申请人提供）：检测“癫痫发作前状态”期间发生的变化的可靠方法可以作为癫痫发作预测的方法，癫痫研究的基准（NIH治愈癫痫会议，2000年和2007年）。我们的初步数据表明，癫痫发作前脑细胞外空间（ECS）的收缩伴随着减少近红外（NIR）光散射检测癫痫发作前的脑电图（EEG）。本申请的目的是确定临床相关癫痫动物模型中癫痫发作前状态的光学特征。本研究的主要目的有三：（1）在体外实验中验证癫痫发作前的光信号可以预测癫痫样活动的假设。我们的初步数据表明，光学相干断层扫描（OCT）衍生的信号先于体外癫痫样活动。在这一目标中，我们将表征的光学变化之前，癫痫样活动在体外海马切片使用同时高分辨率微电极阵列（MEA）和OCT记录。这些实验将充分定义在癫痫发作前状态和体外癫痫样活动期间发生的光学变化。(2)验证癫痫发作前状态的光信号可用于预测体内急性癫痫发作的假设。我们的初步数据表明OCT衍生的反射强度在体内癫痫发作之前降低（Eberle等人，2012年）。在这个目标中，我们将测试通过OCT成像的光学信号检测的能力， 在广泛性和局灶性急性皮质癫痫发作的成熟模型中检测体内癫痫发作前状态。这些实验将验证在不同的癫痫发作模型中癫痫发作前光学变化的存在，并为用光学方法预测体内癫痫发作提供概念验证。(3)验证植入式光纤近红外探针可用于检测癫痫动物癫痫发作前状态的假设。我们的初步数据表明，立体定向植入在小鼠海马的光纤表现出减少近红外反射率在体内急性癫痫发作之前。临床应用的黄金标准是 可靠地检测癫痫动物中的自发性癫痫发作。因此，在这个目的中，我们将我们的新型光纤近红外检测系统应用于一个良好的慢性癫痫动物模型（海马内海人酸模型）。光学检测的灵敏度、特异性和时间过程 将确定慢性自发性癫痫发作之前和期间的NIR反射率变化。这些实验将首次为植入式光纤监测检测癫痫发作的有效性提供原理证明。我们的方法在以下方面是创新的：（i）专注于光学散射变化，而不是像先前研究中那样的吸收变化;（ii） MEA和OCT技术在体外和体内的第一个组合;（iii）使用新的光纤近红外探针，以测量光学变化的深部脑结构之前，癫痫发作在体内首次。拟议的研究是重要的，因为结果将阐明癫痫发作前状态的光学特性，并导致方法来检测前所未有的时空分辨率的局灶性和全身性癫痫发作。

DESCRIPTION (provided by applicant): Reliable means of detecting changes which occur during the "pre-seizure state" could serve as a method of seizure prediction, a benchmark in epilepsy research (NIH Curing Epilepsy Conferences, 2000 and 2007). Our preliminary data indicate pre-seizure constriction in brain extracellular space (ECS) accompanied by reduction in near-infrared (NIR) optical scattering prior to detection of seizure by electroencephalography (EEG). The objective in this application is to determine the optical characteristics of the pre-seizure state in clinically relevant animal models of epilepsy. Three specific aims will be pursued: (1) To test the hypothesis that optical signals of the pre-seizure state can be used to predict epileptiform activity in vitro. Our preliminary data indicate that optical coherence tomography (OCT)-derived signals precede epileptiform activity in vitro. In this Aim, we will characterize the optical changes that occur prior to epileptiform activity in vitro in the hippocampal slice using simultaneous high-resolution microelectrode array (MEA) and OCT recordings. These experiments will fully define the optical changes occurring during the pre-seizure state and during epileptiform activity in vitro. (2) To test the hypothesis that optical signals of the pre-seizure state can be used to predict acute seizures in vivo. Our preliminary data indicate that OCT-derived reflectance intensity decreases prior to seizures in vivo (Eberle et al., 2012). In this Aim, we will test the ability of optical signal detection via OCT imaging to detect the pre-seizure state in vivo in well-established models of generalized and focal acute cortical seizures. These experiments will validate the existence of pre-seizure optical changes in distinct seizure models and provide proof-of-concept for the prediction of seizure onset in vivo with optical methods. (3) To test the hypothesis that implanted fiberoptic NIR probes can be used to detect the pre-seizure state of epileptic animals. Our preliminary data indicate that fiberoptics stereotactically implanted in mouse hippocampus demonstrate reduction in NIR reflectance prior to acute seizures in vivo. The gold standard for clinical application would be to reliably detect a spontaneous seizure in an epileptic animal. Therefore, in this Aim we will apply our novel fiberoptic NIRS detection system to a well-established animal model of chronic epilepsy (intrahippocampal kainic acid model). Sensitivity, specificity, and time course of optical NIR reflectance changes before and during chronic spontaneous seizures will be determined. These experiments will provide proof-of-principle for the efficacy of implanted fiberoptic monitoring to detect epileptic seizures for the first time. Our approach is innovative in (i) focusing on optical scattering changes rather than absorption changes as in prior studies; (ii) the first combination of MEA and OCT technologies in vitro and in vivo; (iii) use of novel fiberoptic NIR probes to measure optical changes in deep brain structures prior to seizures in vivo for the first time. The proposed research is significant because the results will elucidate optical characteristics of the pre-seizure state and lead to methods to detect focal and generalized seizures with unprecedented spatiotemporal resolution.