Song Chenchen, Do Quyen B, Antic Srdjan D, Knöpfel Thomas
Laboratory for Neuronal Circuit Dynamics, Imperial College London, London W12 0NN, UK.
Institute for Systems Genomics, Stem Cell Institute, UConn Health, Farmington, CT 06030-3401, USA.
Int J Mol Sci. 2017 Jul 7;18(7):1461. doi: 10.3390/ijms18071461.
Rapidly progressing development of optogenetic tools, particularly genetically encoded optical indicators, enables monitoring activities of neuronal circuits of identified cell populations in longitudinal in vivo studies. Recently developed advanced transgenic approaches achieve high levels of indicator expression. However, targeting non-sparse cell populations leads to dense expression patterns such that optical signals from neuronal processes cannot be allocated to individual neurons. This issue is particularly pertinent for the use of genetically encoded voltage indicators whose membrane-delimited signals arise largely from the neuropil where dendritic and axonal membranes of many cells intermingle. Here we address this need for sparse but strong expression of genetically encoded optical indicators using a titratable recombination-activated transgene transcription to achieve a Golgi staining-type indicator expression pattern in vivo. Using different transgenic strategies, we also illustrate that co-expression of genetically encoded voltage and calcium indicators can be achieved in vivo for studying neuronal circuit input-output relationships.
光遗传学工具，特别是基因编码的光学指示剂的快速发展，使得在纵向体内研究中能够监测特定细胞群体的神经回路活动。最近开发的先进转基因方法实现了高水平的指示剂表达。然而，针对非稀疏细胞群体导致密集的表达模式，使得来自神经元突起的光信号无法分配到单个神经元。这个问题对于使用基因编码电压指示剂尤为相关，其膜限定信号主要来自许多细胞的树突和轴突膜相互交织的神经毡。在这里，我们通过可滴定的重组激活转基因转录来满足对基因编码光学指示剂稀疏但强表达的需求，以在体内实现高尔基体染色型指示剂表达模式。使用不同的转基因策略，我们还表明，基因编码电压和钙指示剂的共表达可以在体内实现，用于研究神经回路的输入-输出关系。
