雄性和雌性行为之间的先天差别一定是写在他们各自基因组中的，但这些差别是怎样编码截然不同的神经通道的在很大程度上仍然不清楚。通过专注于对果蝇cVA信息素的性别特异反应，Richard Axel及其同事现在识别出了由将嗅觉信号携带到运动中枢的四个连续神经元所组成的一个链条，其中雄性-雌性之间的所有解剖差别都在一个保守的感觉细胞的下游。由这个研究小组建立的方法应能帮助其他研究小组进行神经回路定位――这项工作即便是对相对简单的果蝇大脑来说也仍然是令人望而生畏的。
推荐原文出处：
Nature doi:10.1038/nature09554
A dimorphic pheromone circuit in Drosophila from sensory input to descending output
Vanessa Ruta,Sandeep Robert Datta,Maria Luisa Vasconcelos,Jessica Freeland,Loren L. Looger" Richard Axel
Drosophila show innate olfactory-driven behaviours that are observed in naive animals without previous learning or experience, suggesting that the neural circuits that mediate these behaviours are genetically programmed. Despite the numerical simplicity of the fly nervous system, features of the anatomical organization of the fly brain often confound the delineation of these circuits. Here we identify a neural circuit responsive to cVA, a pheromone that elicits sexually dimorphic behaviours1, 2, 3, 4. We have combined neural tracing using an improved photoactivatable green fluorescent protein (PA-GFP) with electrophysiology, optical imaging and laser-mediated microlesioning to map this circuit from the activation of sensory neurons in the antennae to the excitation of descending neurons in the ventral nerve cord. This circuit is concise and minimally comprises four neurons, connected by three synapses. Three of these neurons are overtly dimorphic and identify a male-specific neuropil that integrates inputs from multiple sensory systems and sends outputs to the ventral nerve cord. This neural pathway suggests a means by which a single pheromone can elicit different behaviours in the two sexes.
