Investigation of long-range GABAergic neurons in the neocortex

 描述(由申请人提供)：新皮质中的长程GABA能(LRG)神经元的性质尚不清楚。尽管在小鼠、猫和猴子中发现了新皮质LRG神经元，但它们的数量很少，使得在完整的大脑中研究它们变得困难。专门标记LRG投射的光遗传学方法可以使对它们的连接性和功能的研究变得容易实验处理。事实上，我们最近已经使用光遗传学来表征一类新的内侧前额叶(MPFC)LRG神经元，这些神经元投射到伏隔核(NAcc)并可以触发急性回避行为。这一建议将结合体内光学成像和条件行为范例与膜片钳电生理学和光遗传学来进一步研究皮质下投射的LRG神经元的连通性和行为功能。这一发现将有助于对神经元和回路如何导致正常和异常行为的长期研究。首先，将检查mPFC LRG神经元的局部和远程连接。将使用膜片钳电生理学、交叉追踪、光遗传学和药理学来确定相同群体的mPFC-NAcc LRG神经元是否也形成局部和/或远程皮质回路，如杏仁基底外侧核。这一目标的发现可能会建立mPFC LRG神经元作为一种同步遥远皮质回路的细胞机制。其次，将探索mPFC-NAcc LRG神经元在条件性行为中的作用。通过修改交叉标记方法，包括一个遗传编码的钙指示剂，mPFC-NAcc LRG神经元的活动可以在体内用纤维光度法在条件性位置偏好(CPP)和厌恶(CPA)过程中进行光学成像。LRG神经元的活动将与条件反射小室的背景相关联，以确定这些神经元如何编码价。利用光遗传学来刺激或抑制mPFC-NACC LRG投射，我还将确定它们是否可以影响条件性行为的获得或表达。这一目的的结果将为mPFC LRG神经元在涉及条件性行为的电路中的作用提供信息。总之，这些目标将促进我们对这种知之甚少的细胞类型的理解，并确定LRG神经元在“自上而下”的抑制过程中可能扮演的角色。

 DESCRIPTION (provided by applicant): The properties of long-range GABAergic (LRG) neurons in the neocortex are poorly defined. Although neocortical LRG neurons have been found in mice, cats, and monkeys, their small numbers make them difficult to study in the intact brain. Optogenetic approaches that specifically label LRG projections can make studies of their connectivity and function experimentally tractable. Indeed, we have recently used optogenetics to characterize a novel class of medial prefrontal (mPFC) LRG neurons that project to the nucleus accumbens (NAcc) and can trigger acute avoidance behaviors. This proposal will incorporate in vivo optical imaging and conditioned behavioral paradigms with patch clamp electrophysiology and optogenetics to further investigate the connectivity and behavioral functions of subcortically-projecting LRG neurons. The findings will add to the long-term study of how neurons and circuits give rise to normal and aberrant behavior. First, the local and distant connectivity of mPFC LRG neurons will be examined. Patch-clamp electrophysiology, intersectional tracing, optogenetics, and pharmacology will be used to determine whether the same population of mPFC-NAcc LRG neurons also forms local and/or distant cortical circuits, such as baslolateral amygdala. Findings from this aim may establish mPFC LRG neurons as a cellular mechanism for synchronizing far-flung cortical circuits. Second, the roles of mPFC-NAcc LRG neurons on conditioned behaviors will be explored. By modifying the intersectional labeling approach to include a genetically encoded calcium indicator, the activity of mPFC- NAcc LRG neurons can be optically imaged in vivo with fiber photometry during conditioned place preference (CPP) and aversion (CPA). LRG neuron activity will be correlated with the context of the conditioned chamber to determine how these neurons encode valence. Using optogenetics to stimulate or inhibit mPFC-NACC LRG projections, I will also determine if they can influence the acquisition or expression of conditioned behaviors. Results from this aim will inform the role of mPFC LRG neurons in circuits involved in conditioned behaviors. Together these aims will advance our understanding of this poorly understood cell type and identify possible roles for LRG neurons in "top-down" inhibitory processes.