Physiology and structure of prefrontal projections to memory and motor circuits

描述(申请人提供)：本项目的目标是了解前额叶执行控制记忆和运动信息的细胞通路基础，以便利用过去的事件来指导未来的行动。内侧前额前扣带回皮质(ACC)由于其与内侧颞叶内嗅核(EC)和运动前皮质(PMC)的强相互联系，被认为是“长期记忆”和“运动计划”系统之间的接口。ACC协调EC和PMC内的活动，从而控制信息流，这两个组织具有独特的解剖电路和独特的网络振荡动力学。行政协调委员会如何监管这两个领域在很大程度上是未知的。虽然许多神经调节剂影响皮质网络动力学，但由于乙酰胆碱(ACh)在学习和记忆中的关键作用，本项目将重点关注它。这个项目的总体假设是，ACC向EC和PMC的投射神经元具有独特的内在、突触和胆碱能神经调节特性，这些特性是它们对突触后靶点的不同控制的基础。梅达拉博士将通过将神经解剖学追踪、体外全细胞膜片钳记录和成年恒河猴切片中逆行标记神经元的细胞内填充相结合的方法来验证这一假设。将使用高分辨率激光扫描共聚焦成像和填充树突的电子显微镜对从中获得记录的神经元进行结构分析。这个项目将导致更好地理解前额叶皮质微电路和潜在的学习和记忆系统执行控制的机制，以及在抑郁症和其他情绪和焦虑障碍中对背景和目标导向行动的错误归因。到目前为止，梅达拉博士的研究一直致力于利用轨迹追踪和电子显微镜技术，了解灵长类前额叶皮质功能专门化的结构突触途径基础。这个拟议的项目将利用梅达拉博士在神经解剖学方面的经验，结合目前在电生理技术方面的培训，在詹妮弗·卢布克博士的指导下，解决前额叶电路中的一些悬而未决的问题。卢布克博士是灵长类动物全细胞膜片钳体外切片记录技术方面为数不多的世界专家之一。该项目还将受益于合作者艾伦·彼得斯博士(著名的电子显微镜和皮质超微结构专家)和道格拉斯·罗森博士(灵长类神经解剖学专家)的支持。Michael Hasselmo博士和Howard Eichenbaum博士将担任该项目的顾问；他们在学习和记忆以及边缘和皮质系统的胆碱能调节方面的专业知识在这些实验的实施过程中将是无价的。在指导阶段，研究重点将集中在ACC投射神经元对EC和PMC的固有、放电和共振特性，以及ACh对它们的调制。在独立阶段，研究将利用双膜片钳记录和双向路径追踪技术研究兴奋性和抑制性突触反应的胆碱能调制、这些投射神经元上的突触结构，以及ACC内EC和PMC相互作用的通路。拟议研究的工作将为Medalla博士提供高质量出版物的数据，以及制定R01竞争申请的初步数据，这将集中在对前额叶皮质微电路结构和功能的进一步研究上。拟议研究中的工作将在波士顿大学进行，这是一所在神经科学领域拥有丰富的多学科研究历史的机构。特别是，医学院的解剖和神经生物学系是一个合作的科学环境，在灵长类大脑的结构和功能方面的开创性工作有着悠久的历史。这项计划中的主要实验将在位于医学院埃文斯生物医学研究中心中心的Luebke实验室进行，该实验室完全配备了在急性和器官型皮质切片和组织细胞培养中进行准备和电生理记录的设备。拟议实验的其他方面将与Rosene实验室合作进行，以进行灵长类脑外科和组织处理，并与彼得斯实验室合作进行电子显微镜下的组织检查。拟议研究的共聚焦成像将在生命科学与工程大楼的生物成像核心进行，由Todd Blute博士管理，配备最先进的Zeiss-510激光扫描共聚焦显微镜。通过其广泛的学术机会、资源和最先进的设施，波士顿大学为Medalla博士的指导和职业发展提供了理想的环境，并执行了拟议项目中的研究目标。北卡罗来纳大学的这些资源将有助于Medalla博士成为电生理学家专家，并启动她自己的独立前沿研究项目，利用突触、细胞和网络水平的结构-功能框架，研究前额叶通路与受体、通道和各种类型的抑制性神经元的特定相互作用。

DESCRIPTION (provided by applicant): The goal of this project is to understand the cellular pathway basis of prefrontal executive control of memory and motor information, for using past events to guide future action. Due to its strong reciprocal connections with the medial temporal entorhinal (EC) and premotor cortices (PMC), the medial prefrontal anterior cingulate cortex (ACC) is strategically positioned to serve as the interface between 'long-term memory' and 'motor planning' systems. The ACC coordinates activity-thereby gating information flow-within EC and PMC, which have distinctive anatomical circuits with unique network oscillatory dynamics. How the ACC regulates these two areas is largely unknown. While a number of neuromodulators influence cortical network dynamics, this project will focus on acetylcholine (ACh) due to its critical role in learning and memory. The overall hypothesis of this project is tht ACC projection neurons to EC and to PMC possess distinct intrinsic, synaptic, and cholinergic neuromodulatory properties that underlie differential control of their postsynaptic targets. Dr. Medalla will test this hypothesis by combining neuroanatomical tract-tracing with in vitro whole-cell patch-clamp recording and intracellular filling of retrogradely-labeled neurons in slices prepared from adult rhesus monkeys (Macaca mulatta). Structural analyses of neurons from which recordings are obtained will be conducted using high-resolution laser-scanning confocal imaging and electron microscopy of filled dendrites. This project will lead to a better understanding of prefrontal cortical microcircuitry and mechanisms underlying executive control of learning and memory systems, and the misattribution of context and drive for goal-directed action in depression and other mood and anxiety disorders. To date Dr. Medalla's research endeavors have been dedicated to understanding the structural synaptic pathway basis of functional specialization in the primate prefrontal cortex, using tract-tracing and electron microscopic techniques. The proposed project will use Dr. Medalla's experience in neuroanatomy combined with current training in electrophysiological techniques to address some outstanding issues in prefrontal circuitry, under the mentorship of Dr. Jennifer Luebke, one of the few world experts in whole-cell patch clamp in vitro slice recording techniques in primates. The project will also benefit from the support of collaborators, Dr. Alan Peters, a renowned expert in electron microscopy and cortical ultrastructure, and Dr. Douglas Rosene, an expert in primate neuroanatomy. Drs. Michael Hasselmo and Howard Eichenbaum will serve as consultants to this project; their expertise in learning and memory as well as cholinergic modulation of limbic and cortical systems will be invaluable during the implementation of these experiments. In the mentored phase, studies will focus on the intrinsic, firing and resonance properties of ACC projection neurons to EC and PMC, and their modulation by ACh. In the independent phase, studies will address the cholinergic modulation of excitatory and inhibitory synaptic responses and the structure of synapses onto these projection neurons, and the interaction EC and PMC pathways within ACC using dual patch-clamp recording and bi-directional pathway tracing. The work from the proposed studies will provide Dr. Medalla with data for high quality publications as well as preliminary data for formulating a competitive application for an R01, which will be centered on further studies of the structure and function of prefrontal cortical microcircuitry. The work in the proposed studies will be conducted at Boston University, an institution with a rich history of well-established multidisciplinary research in th field of Neuroscience. In particular, the Department of Anatomy and Neurobiology at the School of Medicine is a collaborative scientific environment with a long- standing history of seminal work on the structure and function of the primate brain. The main experiments in this proposal will be conducted in the Luebke Laboratory, located at the heart of the Medical Campus Evans Biomedical Research Center, which is fully equipped for preparation and electrophysiologic recording in acute and organotypic cortical slices and tissue cell cultures. Other aspects of the proposed experiments will be conducted in collaboration with the Rosene Laboratory for primate brain surgery and tissue processing, and the Peters Laboratory for examining tissue under the electron microscope. The confocal imaging for the proposed studies will be conducted in the Biology Imaging Core at the Life Science and Engineering Building, managed by Dr. Todd Blute, equipped with a state-of-the art Zeiss-510 laser-scanning confocal microscope. Through its extensive academic opportunities, resources, and state-of-the art facilities, BU provides an ideal environment for the mentoring and career development of Dr. Medalla, and the execution of the research goals in the proposed project. These resources at BU will facilitate the training of Dr. Medalla to become an expert electrophysiologist and initiate her own independent cutting-edge research program that investigates prefrontal pathway-specific interactions with receptors, channels, and diverse types of inhibitory neurons, using a structure-function framework at the synaptic, cellular and network levels.