Optogenetic Population Clamp to Study Long-term Plasticity in Vitro

描述（由申请人提供）： 这是一个多学科的_生物工程研究赠款_（BRG）提案，以响应PA-10-009，具有设计驱动和发现驱动的元素。 它基于一个越来越流行的假设，即许多神经系统疾病的进展植根于已经变得适应不良的稳态可塑性。 这些可以被归类为去传入障碍，其中在CNS组织中，破坏性同步群体爆发活动在数天或数周内发展，CNS组织的输入已经被白色损伤、中风或感觉受体或外周神经的损伤大大减少或消除。 群体爆发的低频、高振幅放电可以表现为癫痫发作、慢性疼痛、肌张力障碍、耳鸣或其他致残症状，这取决于神经系统的哪个部分在传入神经阻滞后变得过度兴奋。 药物治疗往往完全无效。 这使得许多人提出了直接的、局部的脑刺激疗法，包括植入电极或经颅磁刺激。 光遗传学提供了一种更加局部化和特定的方式来刺激脑组织，因为它可以使特定的神经细胞类型对特定颜色的光敏感。 聪明的是，光可以激活或沉默目标神经元，努力使异常的神经元正常化。 活动 基于一种成功的闭环方法，在培养的皮层网络中用多电极阵列刺激来抑制神经元样群体爆发，该项目是开发和优化一种闭环光遗传学工具，以获得对稳态可塑性机制的控制，并逆转去传入组织表达同步爆发的趋势。 这种“群体钳”将采用来自多电极阵列基板的细胞外记录作为反馈信号，快速连续地调节彩色光脉冲，选择性地激活和抑制不同的神经元类型，以保持所需的活动水平。 表达群体放电的皮层网络，由于典型的离体制剂的传入神经阻滞，将被夹在不同的活动设置点-天。 稳态反应，如突触强度的变化，将通过细胞内记录和细胞外测量群体活动来监测。 使用腺相关病毒载体针对兴奋性锥体神经元或抑制性中间神经元的光遗传学构建体的组合将在它们充当可操纵稳态可塑性的手柄的能力方面进行比较。 将开发反馈控制算法，使最有效和持久的缓解人口爆发，同时增强网络功能的措施，如复杂的光输入和尖峰输出之间的相互信息。 通过提供一个可访问和可操作的测试床来研究不同的结构和参数，光遗传种群钳将为通过植入光纤采用闭环光刺激的各种神经系统疾病的基因治疗铺平道路。

DESCRIPTION (provided by applicant): This is a multi-disciplinary _Bioengineering Research Grants_ (BRG) proposal in response to PA-10-009, with design-driven and discovery-driven elements. It is based on a hypothesis that is gaining in popularity, that the progression of a number of neurological disorders is rooted in homeostatic plasticity that has become maladaptive. These can be classified as de-afferentation disorders, where disruptive synchronized population bursting activity develops across days or weeks, in CNS tissue whose inputs have been greatly reduced or eliminated by white matter damage, stroke, or damage to sensory receptors or peripheral nerves. Low-frequency, high-amplitude electrical discharges from population bursting can manifest as seizures, chronic pain, dystonia, tinnitus, or other disabling symptoms, depending on which part of the nervous system has become hyper-excitable after deafferentation. Pharmacological treatments are often completely ineffective. This has lead many to propose therapies that involve direct, localized brain stimulation with implanted electrodes or transcranial magnetic stimulation. Optogenetics provides a much more localized and specific way to stimulate brain tissue, because it can render defined neural cell types sensitive to light of specific colors. Wit it, light can either activate or silence targeted neurons in an effort to normalize aberrant neural activity. Based on a successful closed-loop approach to quieting seizure-like population bursting in cultured cortical networks with multi-electrode array stimulation, this project is to develop and optimize a closed-loop optogenetic tool to gain control over homeostatic plasticity mechanisms, and to reverse the tendency of deafferented tissue to express synchronized bursting. This _Population Clamp_ will employ extracellular recording from multi-electrode array substrates as the feedback signal, to rapidly and continuously adjust pulses of colored light, selectively activating and inhibiting different neuron types, to maintain a desired activity level. Cortical networks expressing population discharges due to the deafferentation typical of in vitro preparations will be clamped to different activity set----points for days. Homeostatic responses, such as changes in synaptic strength, will be monitored with intracellular recording and extracellular measures of population activity. Combinations of optogenetic constructs, directed at excitatory pyramidal neurons or inhibitory interneurons using adeno-associated viral vectors, will be compared in terms of their ability to serve as handles by which homeostatic plasticity can be manipulated. Feedback control algorithms will be developed that enable the most effective and enduring remission of population bursting, while enhancing measures of network function, such as the mutual information between complex light input and spiking output. By providing an accessible and manipulable test bed for studying different constructs and parameters, the Optogenetic Population Clamp will pave the way for gene-therapeutic treatments of a variety of neurological disorders that employ closed-loop light stimulation via implanted fiber optics.