Spatial Receptive Fields for Odor Localization
Spatial Receptive Fields for Odor Localization
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DOI：
10.1016/j.cub.2017.12.055
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发表时间：
2018-02-19
期刊：
影响因子：
9.2
通讯作者：
Mizunami, Makoto
中科院分区：
文献类型：
--
作者：
Nishino, Hiroshi;Iwasaki, Masazumi;Mizunami, Makoto
动物依靠嗅觉在复杂的嗅觉环境中导航，但允许动物对气味环境的空间结构进行编码的机制尚不清楚。为了获取气味的空间分布信息，动物可能依赖于双侧嗅觉器官，比较两侧气味强度和时间的差异[1-6]，或者对随后的采样进行时空信号整合[1-6]。美洲蜚蠊即使在去除一根天线后也能有效地定位性信息素的来源，这表明双边比较并不是该物种气味定位的先决条件[8,9]。同源嗅觉感觉神经元（OSNs）起源于鞭毛上的不同位置，但具有相同的嗅觉受体，会聚到触角叶内的同一肾小球上，这被认为是导致空间信息丢失的原因。在这里，我们鉴定了12种信息素响应投射神经元（PNs），每一种都具有空间调谐的感受野。(1)大肾小球（MG）内PNs末端的天线状组织和(2)大肾小球内PNs树突状树突的刻板区隔化结合在一起，允许编码信息素的空间位置。此外，每种PN类型支配蘑菇体的不同隔室，提供沿嗅觉回路编码空间嗅觉信息的手段。最后，MG - pn同时表现出兴奋性和抑制性空间感受野，并根据刺激几何形状的变化调节其反应。总之，我们提出了一种信息素空间分布的编码机制，扩展了我们对气味编码和昆虫定位性伴侣策略的理解。
Animals rely on olfaction to navigate through complex olfactory landscapes, but the mechanisms that allow an animal to encode the spatial structure of an odorous environment remain unclear. To acquire information about the spatial distribution of an odorant, animals may rely on bilateral olfactory organs and compare side differences of odor intensity and timing [1-6] or may perform spatial and temporal signal integration of subsequent samplings [7]. The American cockroach can efficiently locate a source of sex pheromone even after the removal of one antenna, suggesting that bilateral comparison is not a prerequisite for odor localization in this species [8, 9]. Cognate olfactory sensory neurons (OSNs) originating from different locations on the flagellum, but bearing the same olfactory receptor, converge onto the same glomerulus within the antennal lobe, which is thought to result in a loss of spatial information. Here, we identified 12 types of pheromone-responsive projection neurons (PNs), each with spatially tuned receptive field. The combination of (1) the antennotopic organization of OSNs terminals and (2) the stereotyped compartmentalization of PNs' dendritic arborization within the macroglomerulus (MG), allows encoding the spatial position of the pheromone. Furthermore, each PN type innervates a different compartment of the mushroom body, providing the means for encoding spatial olfactory information along the olfactory circuit. Finally, MG PNs exhibit both excitatory and inhibitory spatial receptive fields and modulate their responses based on changes in stimulus geometry. In conclusion, we propose a mechanism for encoding information on the spatial distribution of a pheromone, expanding both our understanding of odor coding and of the strategies insects adopt to localize a sexual mate.