Flood Thomas F, Gorczyca Michael, White Benjamin H, Ito Kei, Yoshihara Motojiro
Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts.
G3 (Bethesda). 2013 Oct 3;3(10):1629-37. doi: 10.1534/g3.113.006205.
Drosophila is increasingly used for understanding the neural basis of behavior through genetically targeted manipulation of specific neurons. The primary approach in this regard has relied on the suppression of neuronal activity. Here, we report the results of a novel approach to find and characterize neural circuits by expressing neuronal activators to stimulate subsets of neurons to induce behavior. Classical electrophysiological studies demonstrated that stimulation of command neurons could activate neural circuits to trigger fixed action patterns. Our method was designed to find such command neurons for diverse behaviors by screening flies in which random subsets of brain cells were activated. We took advantage of the large collection of Gal4 lines from the NP project and crossed 835 Gal4 strains with relatively limited Gal4 expression in the brain to flies carrying a UAS transgene encoding TRPM8, a cold-sensitive ion channel. Low temperatures opened the TRPM8 channel in Gal4-expressing cells, leading to their excitation, and in many cases induced overt behavioral changes in adult flies. Paralysis was reproducibly observed in the progeny of crosses with 84 lines, whereas more specific behaviors were induced with 24 other lines. Stimulation performed using the heat-activated channel, TrpA1, resulted in clearer and more robust behaviors, including flight, feeding, and egg-laying. Through follow-up studies starting from this screen, we expect to find key components of the neural circuits underlying specific behaviors, thus providing a new avenue for their functional analysis.
果蝇越来越多地被用于通过对特定神经元进行基因靶向操纵来理解行为的神经基础。在这方面的主要方法依赖于抑制神经元活动。在此，我们报告一种新方法的结果，即通过表达神经元激活剂来刺激神经元子集以诱导行为，从而寻找和表征神经回路。经典的电生理研究表明，刺激指令神经元可以激活神经回路以触发固定动作模式。我们的方法旨在通过筛选脑细胞随机子集被激活的果蝇来找到针对不同行为的此类指令神经元。我们利用了来自NP项目的大量Gal4品系，并将835个在大脑中Gal4表达相对有限的Gal4菌株与携带编码TRPM8（一种冷敏感离子通道）的UAS转基因的果蝇杂交。低温打开了Gal4表达细胞中的TRPM8通道，导致它们兴奋，并且在许多情况下诱导成年果蝇出现明显的行为变化。在与84个品系杂交的后代中可重复观察到麻痹现象，而用其他24个品系诱导出了更特定的行为。使用热激活通道TrpA1进行刺激导致更清晰、更强烈的行为，包括飞行、进食和产卵。通过从这个筛选开始的后续研究，我们期望找到特定行为背后神经回路的关键组成部分，从而为其功能分析提供一条新途径。
