有一種小鼠不知道害怕,。更準確地說，它對于討厭的氣味不能產(chǎn)生先天性的行為反應,，而這種反應正常情況下可以保護小鼠不去吃腐爛的食物或避開某種捕食者的氣味,。在這種小鼠中，其嗅覺上皮的一個區(qū)域(鼻腔內(nèi)一個對氣味敏感的上皮組織)中的嗅覺神經(jīng)元,，已經(jīng)被白喉毒素基因的定向表達除掉了,。雖然沒有先天的厭惡行為，但該小鼠卻能探測和辨別討厭的氣味,，并且可以條件性地作出厭惡反應,。這些結(jié)果表明，同免疫系統(tǒng)一樣,，小鼠的嗅覺系統(tǒng)也具有“硬件連接的”,、通過遺傳程序編碼的神經(jīng)回路，它們與后天獲得的、與先天系統(tǒng)聯(lián)系在一起的適應性回路是并行的,。
原始出處:
Nature 450, 503-508 (22 November 2007) | doi:10.1038/nature06281; Received 3 August 2007; Accepted 14 September 2007; Published online 7 November 2007
Innate versus learned odour processing in the mouse olfactory bulb
Ko Kobayakawa1,6, Reiko Kobayakawa1,6, Hideyuki Matsumoto2, Yuichiro Oka1, Takeshi Imai1, Masahito Ikawa3, Masaru Okabe3, Toshio Ikeda4, Shigeyoshi Itohara4, Takefumi Kikusui5, Kensaku Mori2 & Hitoshi Sakano1
Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0032, Japan
Department of Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
Research Institute for Microbial Diseases, The Osaka University, Osaka 565-0871, Japan
Laboratory for Behavioral Genetics, Brain Science Institute, RIKEN, Saitama 351-0198, Japan
Laboratory of Veterinary Ethology, The University of Tokyo, Tokyo 113-8657, Japan
These authors contributed equally to this work.
Correspondence to: Hitoshi Sakano1 Correspondence and requests for materials should be addressed to H.S. (Email: [email protected]).
Abstract
The mammalian olfactory system mediates various responses, including aversive behaviours to spoiled foods and fear responses to predator odours. In the olfactory bulb, each glomerulus represents a single species of odorant receptor. Because a single odorant can interact with several different receptor species, the odour information received in the olfactory epithelium is converted to a topographical map of multiple glomeruli activated in distinct areas in the olfactory bulb. To study how the odour map is interpreted in the brain, we generated mutant mice in which olfactory sensory neurons in a specific area of the olfactory epithelium are ablated by targeted expression of the diphtheria toxin gene. Here we show that, in dorsal-zone-depleted mice, the dorsal domain of the olfactory bulb was devoid of glomerular structures, although second-order neurons were present in the vacant areas. The mutant mice lacked innate responses to aversive odorants, even though they were capable of detecting them and could be conditioned for aversion with the remaining glomeruli. These results indicate that, in mice, aversive information is received in the olfactory bulb by separate sets of glomeruli, those dedicated for innate and those for learned responses.
