Mapping the escape from inhibition.

绘制逃离抑制的图谱。

• 批准号: 8232069
• 负责人: Kevin J. Staley
• 金额: $ 33.55万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8232069
• 关键词: Address; Anatomy; Animals; Area; Brain; Brain Injuries; Calcium; Cells; Characteristics; Color; Complex; Computer Simulation; Convulsants; Data; Development; Elements; Epilepsy; Excitatory Synapse; Failure; Feedback; Figs - dietary; Financial compensation; Fire - disasters; Functional disorder; Genetic; Glutamates; Growth; Health; Homeostasis; Human; Image; Imagery; Imaging Device; In Vitro; Indium; Individual; Injury; Interneurons; Label; Lasers; Location; Maps; Mediating; Mental Depression; Microscopy; Modeling; Mus; Myoepithelial cell; Neurons; Neurotransmitters; Output; Parvalbumins; Pathogenesis; Pathway interactions; Patients; Pattern; Process; Pyramidal Cells; Recovery; Refractory; Runaway; Running; Scanning; Seizures; Slice; Speed; Synapses; Techniques; Testing; Therapeutic Intervention; Time; fluorophore; gamma-Aminobutyric Acid; grasp; in vivo; inhibitory neuron; insight; optogenetics; photoactivation; prevent; ratiometric; response; simulation; synaptic depression; theories; tool

DESCRIPTION (provided by applicant): Feedback inhibition is the process by which activity in principal neurons stimulates interneurons to release the inhibitory neurotransmitter GABA onto the active principal neurons to prevent runaway excitation. Failure of feedback inhibition is thus a critical element in most theories of the pathogenesis of seizures. However, the functional anatomy of feedback inhibition in the normal brain and epileptic focus is unknown. Recent developments in optogenetics and multiphoton microscopy have made it possible to address this question directly. Here we propose to combine channelrhodopsin-mediated photoactivation of targeted pyramidal cells with high-speed multiphoton imaging of the responses in interneurons expressing the calcium fluorophore yellow chameleon 3.6. These techniques will allow us to define the location of the interneurons that are activated by the target pyramidal cell. After brain injury, the loss of principal neurons and interneurons is compensated by sprouting of new synaptic connections. Our computer modeling suggests that the circuit complexity engendered by this sprouting leaves the interneurons vulnerable to activity-induced synaptic depression that permits runaway excitation and seizures. We hypothesize therefore that epileptic circuits will be defined by characteristic changes in the anatomy of feedback inhibition: more principal neurons will share the same interneuron feedback networks, and individual interneurons will be activated by a wider anatomical range of pyramidal cells, so that the anatomical complexity of local feedback circuits will be increased in epileptic foci. We will test this hypothesis directly with the new optogenetic and microscopy tools in vitro using chronically epileptic organotypic slice cultures, and in vivo using chronically epileptic animals. This data will provide a critical new insight into the pathophysiology of epilepsy that we have not been able to acquire despite wonderfully detailed electrophysiological and classical anatomical studies. Testing for characteristic circuit alterations in epilepsy will make possible new classes of therapeutic interventions including pharmacological manipulation of activity-dependent depression, as well as preemptive activation of critical circuit elements.

描述（由申请人提供）：反馈抑制是主要神经元的活动刺激中间神经元将抑制性神经递质 GABA 释放到活跃的主要神经元上以防止失控兴奋的过程。因此，反馈抑制的失败是大多数癫痫发作发病机制理论的关键要素。然而，正常大脑和癫痫病灶中反馈抑制的功能解剖结构尚不清楚。光遗传学和多光子显微镜的最新发展使得直接解决这个问题成为可能。在这里，我们建议将通道视紫红质介导的目标锥体细胞的光激活与表达钙荧光团黄色变色龙 3.6 的中间神经元的反应的高速多光子成像结合起来。这些技术将使我们能够定义由目标锥体细胞激活的中间神经元的位置。脑损伤后，主要神经元和中间神经元的损失可以通过新突触连接的萌发来补偿。我们的计算机模型表明，这种萌芽产生的电路复杂性使中间神经元容易受到活动引起的突触抑制的影响，从而导致失控的兴奋和癫痫发作。因此，我们假设癫痫回路将由反馈抑制解剖学的特征性变化来定义：更多的主要神经元将共享相同的中间神经元反馈网络，并且单个中间神经元将被更广泛的锥体细胞解剖范围激活，从而使解剖学的复杂性癫痫病灶中的局部反馈回路会增加。我们将使用新的光遗传学和显微镜工具直接在体外使用慢性癫痫器官切片培养物以及在体内使用慢性癫痫动物来测试这一假设。这些数据将为癫痫的病理生理学提供重要的新见解，尽管进行了非常详细的电生理学和经典解剖学研究，但我们仍无法获得这一见解。测试癫痫的特征性回路改变将使新型治疗干预措施成为可能，包括对活动依赖性抑郁症的药理学操作，以及先发制人地激活关键回路元件。