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导致死亡。这些反应既取决于外部世界，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其周围环境特征的关注程度的影响。先前的研究表明，注意力的增加与皮质中的去兴奋性增加有关，其特征是低振幅，快速振荡，反映了以不同速率发射的神经元群体。较少的注意力与同步状态相关，其特征是高振幅，慢振荡，反映了神经元群体活动的更多相似性。由注意力增加驱动的去兴奋化主要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。相反，去铁化后铁化的机制仍然几乎完全未知。然而，最近的研究表明，这种神经元化可能是由皮质中的非神经元细胞群（星形胶质细胞）主动调节的。如果这是真的，这一发现可能会从根本上改变我们概念化注意力和行为机制的框架。 目前的建议的总体目标是调查是否星形胶质细胞是积极的球员在皮层神经元化后乙酰胆碱（ACh）驱动的注意力增加。为了解决这个问题，我将量化星形胶质细胞的活动，注意力的生物学相关性，以及清醒，头部固定小鼠的初级视觉皮层中的唤醒和胆碱能活动增加期间的皮层状态。在目标1中，我将检验星形胶质细胞通过胆碱能信号机制对增强的唤醒做出反应的假设。在目标2中，我将检验这一假设，即星形胶质细胞的反应是必要的皮质钙化。总之，这一提议将确定乙酰胆碱驱动的注意力增加后星形胶质细胞信号传导的功能。这些结果将使我们能够剖析皮层神经元化的机制，并获得对这种现象的新见解，这对正确的行为表现至关重要。许多疾病，如自闭症和精神分裂症，与受损的皮层状态调节和感觉处理，因此，从这个建议的结果将有进一步的影响，治疗注意力相关的疾病。 UCSF的Poskanzer实验室是进行本提案中概述的实验的理想场所。Poskanzer博士是星形胶质细胞和群体水平活动的体内记录专家，具有成功完成拟议实验所需的技术和概念的广泛知识。此外，我将接受我的共同赞助人斯特赖克博士在皮层生理学和神经调节整合方面的专家培训，他也是解剖乙酰胆碱在注意力相关视觉回路中作用的领导者。最后，我已经组建了一个科学委员会，由该项目几个方面的专家组成，他们将在拟议研究的各个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.