Remote effects of focal hippocampal seizures on neocortical function

项目总结/摘要 癫痫发作对神经系统功能有局部和远程影响。颞叶癫痫是一种常见的 和使人衰弱的神经系统疾病，其特征在于由边缘结构引起的局灶性癫痫发作，包括 海马体有趣的是，局灶性颞叶癫痫发作往往会导致功能缺陷，如受损 意识，这不是预期的局部海马损伤单独。人局灶性颞叶 意识受损的癫痫发作在脑电图（EEG）上显示慢波， 新皮层的脑血流，远离海马体。局灶性癫痫发作的机制 在海马体中引起新皮层功能抑制的原因尚不清楚。我们之前在老鼠身上的研究 局灶性边缘系统癫痫模型再现了人类的发现，并表明皮质下 在癫痫发作期间，觉醒会导致意识受损。重要的是，皮层下唤醒的神经刺激 系统能够恢复癫痫发作期间的皮质功能和行为反应，为癫痫发作提供了希望。 恢复了人类癫痫患者的觉醒因此，我们的中心假设是局灶性边缘系统癫痫发作减少 皮层下觉醒，导致皮层慢波和意识受损。但根本 这些变化的机制尚未确定。我们最近开发了一种新颖的清醒头部固定 局灶性边缘癫痫发作的小鼠模型，提供了独特的机会，研究网络，神经递质 以及与行为相关的神经机制。我们发现，这两个增加抑制和减少 在边缘系统癫痫发作中，兴奋可能与抑制的皮层下唤醒并行。此外，抑郁 多个神经递质系统中的唤醒可能导致皮质功能受损。我们现在计划 利用清醒小鼠模型的优势，采用高场功能磁共振成像技术，遗传学， 编码荧光神经递质传感器，光遗传学，单细胞电生理学和行为 测试以充分研究癫痫发作中唤醒受损的机制。因此，我们的目标是首先 在清醒小鼠模型中研究局灶性边缘系统癫痫发作中唤醒受损的网络机制。 我们将通过功能磁共振成像绘制皮层和皮层下网络，然后进行直接的电生理记录， 模拟和断开实验，以识别关键网络节点。其次，我们将分析 神经递质的变化在抑郁的皮质功能。我们将使用基因编码的荧光指示剂 和光遗传学来确定抑郁症患者中抑制增加和兴奋减少的作用。 皮层下唤醒;并将研究哪些唤醒神经递质有助于受损的皮层功能 和行为。第三，我们将把单个神经元的活动与局灶性边缘癫痫发作中的行为联系起来， 确定的皮层下唤醒神经元的单细胞记录和皮层神经元的全细胞记录。 在清醒模式中，跨这些层次的信息整合将具有重要的转化价值， 指导开发旨在恢复癫痫发作期间和之后的意识的新疗法。

PROJECT SUMMARY / ABSTRACT Seizures have both local and remote effects on nervous system function. Temporal lobe epilepsy is a common and debilitating neurological disorder, characterized by focal seizures arising from limbic structures, including the hippocampus. Interestingly, focal temporal lobe seizures often cause functional deficits such as impaired consciousness, which is not expected from local hippocampal impairment alone. Human focal temporal lobe seizures with impaired consciousness show slow waves on electro-encephalography (EEG) and decreased cerebral blood flow in the neocortex, distant from the hippocampus. The mechanisms by which focal seizures in the hippocampus cause depressed function in the neocortex are not known. Our previous work in a rat model with focal limbic seizures reproduced the human findings and suggested that decreased subcortical arousal produces impaired consciousness during seizures. Importantly, neurostimulation of subcortical arousal systems was capable of restoring cortical function and behavioral responses during seizures, offering hope for restored arousal in human epilepsy. Therefore, our central hypothesis is that focal limbic seizures decrease subcortical arousal, causing cortical slow waves and impaired consciousness. However, the fundamental mechanisms of these changes have not been determined. We recently developed a novel awake head-fixed mouse model of focal limbic seizures, providing unique opportunities to investigate network, neurotransmitter and neuronal mechanisms in relation to behavior. We found that both increased inhibition and decreased excitation may contribute in parallel to depressed subcortical arousal in limbic seizures. In addition, depressed arousal in multiple neurotransmitter systems may contribute to impaired cortical function. We now plan to capitalize on strengths of the awake mouse model to employ techniques including high field fMRI, genetically encoded fluorescent neurotransmitter sensors, optogenetics, single cell electrophysiology and behavioral testing to fully investigate the mechanisms of impaired arousal in seizures. Therefore, our aims are to first investigate the network mechanisms of impaired arousal in focal limbic seizures in the awake mouse model. We will map cortical and subcortical networks by fMRI, followed by direct electrophysiological recordings, stimulation and disconnection experiments to identify key network nodes. Second, we will analyze the neurotransmitter changes in depressed cortical function. We will use genetically encoded fluorescent indicators and optogenetics to determine the roles of increased inhibition and decreased excitation in depressed subcortical arousal; and will investigate which arousal neurotransmitters contribute to impaired cortical function and behavior. Third, we will relate the activity of single neurons to behavior in focal limbic seizures, using juxtacellular recordings of identified subcortical arousal neurons and whole cell recordings of cortical neurons. The integration of information across these levels in the awake model will have important translational value to guide development of new treatments aimed at restoring consciousness during and following seizures.