Investigating the role of acetylcholine-induced astrocyte activity on local cortical state

动物对外界刺激的反应对其生存至关重要；对威胁性刺激不采取行动可能会导致死亡。这些反应既依赖于外部世界，也取决于动物的内部大脑状态，而内部大脑状态本身又受到动物对周围特征的注意程度的影响。以前的工作表明，注意力的增加与皮质的去同步性增加有关，皮层的去同步性的特征是低幅度、快速的振荡，反映出以不同速率放电的神经元群体。注意力较少与同步状态有关，同步状态的特征是高幅度、慢振荡，反映出神经元群体活动的更多相似性。注意力增加导致的去同步化很大程度上是由于神经调节输入，包括从基底前脑到皮质的胆碱能驱动增加。相比之下，去同步化后再同步化的潜在机制几乎完全未知。然而，最近的工作表明，这种再同步化可能受到皮质中非神经元细胞群(星形胶质细胞)的积极调控。如果这是真的，这一发现可能会从根本上改变我们对注意力和行为机制进行概念化的框架。本研究的总体目标是研究在乙酰胆碱(ACh)引起的注意力增加后，星形胶质细胞是否是皮质再同步化的活跃参与者。为了解决这一问题，我将量化星形胶质细胞的活动，注意的生物相关性，以及在觉醒和头部固定小鼠初级视觉皮质胆碱能活动增加期间的皮质状态。在目标1中，我将测试星形胶质细胞通过胆碱能信号机制对觉醒增加做出反应的假设。在目标2中，我将验证这样的假设，即星形胶质细胞的反应对于大脑皮层的再同步是必要的。总而言之，这一提议将决定ACh引起的注意力增加后星形胶质细胞信号的功能。这些结果将使我们能够剖析皮质再同步化的机制，并对这一现象获得新的见解，这对正常的行为表现至关重要。许多障碍，如自闭症和精神分裂症，都与皮质状态调节和感觉处理受损有关，因此这一提议的结果将对治疗注意力相关障碍产生进一步的影响。加州大学旧金山分校的Poskanzer实验室是进行这项提议中概述的实验的理想场所。波斯坎泽博士是在体记录星形细胞和种群水平活动的专家，对成功完成拟议的实验所需的技术和概念有广泛的了解。此外，我还将从我的共同赞助人之一史崔克博士那里接受皮质生理学和神经调节整合方面的专家培训，他也是剖析ACh在与注意力相关的视觉回路中的作用的领导者。最后，我已经组建了一个科学委员会，由该项目的几个方面的专家组成，他们将在拟议研究的所有方面提供出色的科学支持。

An animal's response to external stimuli is critical to its survival; inaction to threatening stimuli could result in death. These responses are dependent on both the external world and the internal brain state of the animal, which itself is influenced by how attentive that animal is to features in its surroundings. Previous work has shown that increased attention is associated with increased desynchrony in the cortex, which is characterized by low-amplitude, fast oscillations reflective of populations of neurons firing at different rates. Less attention is associated with a synchronized state, characterized by high-amplitude, slow oscillations that reflect more similarity in neuronal population activity. The desynchronization driven by increases in attention are largely due to neuromodulatory input, including increased cholinergic drive to the cortex from the basal forebrain. In contrast, the mechanisms underlying resynchronization after desynchronization remain almost completely unknown. Recent work, however, suggests that this resynchronization may be actively regulated by non-neuronal cell populations (astrocytes) in cortex. If true, this finding could fundamentally alter the framework with which we conceptualize mechanisms of attention and behavior. The overall goal of the current proposal is to investigate whether astrocytes are active players in cortical resynchronization following acetylcholine (ACh)-driven increases in attention. To address this, I will quantify astrocyte activity, biological correlates of attention, and cortical state during periods of increased arousal and cholinergic activity in the primary visual cortex of awake, head-fixed mice. In Aim 1, I will test the hypothesis that astrocytes respond to increased arousal via cholinergic signaling mechanisms. In Aim 2, I will test the hypothesis that this astrocyte response is necessary for cortical resynchronization. Together, this proposal will determine the function of astrocyte signaling following ACh-driven increases in attention. These results will allow us to dissect the mechanisms of cortical resynchronization, and gain novel insight into this phenomenon that is critical for proper behavioral performance. Many disorders, such as autism and schizophrenia, are associated with impaired cortical state regulation and sensory processing, and thus results from this proposal will have further implications for treating attention-related disorders. The Poskanzer lab at UCSF is an ideal place to carry out the experiments outlined in this proposal. Dr. Poskanzer is an expert in in vivo recording of astrocytic and population-level activity, with extensive knowledge of the techniques and concepts necessary for successful completion of the proposed experiments. Additionally, I will receive expert training in cortical physiology and neuromodulatory integration from my Co-Sponsor Dr. Stryker, who has also been a leader in dissecting the role of ACh in attention-related visual circuits. Lastly, I have assembled a Scientific Committee with experts in several aspects of the project, and they will provide excellent scientific support during all aspects of the proposed research.