A MOLECULAR CODE FOR CONNECTIVITY IN THE NEOCORTEX

描述(申请人提供)：新大脑皮层由数十亿个神经元组成，具有数万亿个连接，负责感知和抽象推理等认知任务。皮质异常与毁灭性的神经精神疾病有关，包括自闭症谱系障碍和精神分裂症，进一步强调了了解皮质功能的重要性。尽管在了解单个神经元的特性方面取得了重大进展，但我们才刚刚开始了解管理新皮质回路组装的规则。该领域的一个主要悬而未决的问题是，分子机制是否会在单个细胞的水平上指导神经电路的接线图。 换句话说，有没有一个基因蓝图来管理大脑皮层回路的局部连接？这一问题在技术上具有挑战性，因为它需要同时分析神经元连接和单个皮质神经元水平上的基因表达谱。此外，它还需要收集大量数据以及先进的分析技术来破解连接的分子密码。我们建议使用多个全细胞膜片钳记录结合单细胞逆转录(RT)-PCR来研究聚集性原钙粘附素基因家族是否为神经回路组装提供了分子密码。成簇的原钙粘附素已被证明在单个神经元中以组合密码表达，在突触形成过程中高度表达，并定位于突触。因此，簇状原钙粘附素是形成新皮质回路的主要候选分子。然而，它们在指导特定突触形成方面的作用并不是 由于这类实验的难度较大，直接进行了测试。此外，该项目具有挑战性的方面使其不太可能由更传统的机制提供资金。这些实验的结果可能会彻底改变我们对神经回路组装的理解，并导致在电路水平上研究神经精神障碍的更有原则的方法。

DESCRIPTION (provided by applicant): The neocortex consists of billions of neurons with trillions of connections, and is responsible for cognitive tasks such as perception and abstract reasoning. Cortical abnormalities are associated with devastating neuropsychiatric illnesses including autism spectrum disorders and schizophrenia, further underscoring the importance of understanding how the cortex functions. Despite major advances in understanding the properties of individual neurons, we are just beginning to understand the rules that govern the assembly of neocortical circuits. One major unanswered question in the field is whether molecular mechanisms direct the wiring diagram of neural circuits at the level of individual cells. In other words, is there a genetic blue print that governs the local wiring of cortical circuits? Tis question is technically challenging to address because it will require simultaneous analysis of both neuronal connectivity and the gene expression profile at the level of single cortical neurons. Moreover, it will require massive amounts of data to be collected as well as advanced analysis techniques to crack the molecular code of connectivity. We propose to use multi-whole-cell patch clamp recording combined with single-cell reverse transcription (RT)-PCR to investigate whether the clustered protocadherin gene family provides a molecular code for neural circuit assembly. The clustered protocadherins have been shown to be expressed in a combinatorial code in individual neurons, are highly expressed during synaptogenesis, and localize to synapses. Thus, clustered protocadherins are the leading candidate molecules for shaping neocortical circuits. However, their role in instructing specific synapse formation has not been directly tested due to the difficulty of these types of experiments. Furthermore, the challenging aspects of this project make it unlikely to be funded by more traditional mechanisms. The results of these experiments could revolutionize our understanding of neural circuit assembly and lead to a more principled approach to studying neuropsychiatric disorders at the circuit level.