Manzini Ivan, Brase Christoph, Chen Tsai-Wen, Schild Detlev
Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
J Physiol. 2007 Jun 1;581(Pt 2):567-79. doi: 10.1113/jphysiol.2007.130518. Epub 2007 Mar 8.
Glomeruli in the vertebrate olfactory bulb (OB) appear as anatomically discrete modules receiving direct input from the olfactory epithelium (OE) via axons of olfactory receptor neurons (ORNs). The response profiles with respect to amino acids (AAs) of a large number of ORNs in larval Xenopus laevis have been recently determined and analysed. Here we report on Ca(2+) imaging experiments in a nose-brain preparation of the same species at the same developmental stages. We recorded responses to AAs of glomeruli in the OB and determined the response profiles to AAs of individual glomeruli. We describe the general features of AA-responsive glomeruli and compare their response profiles to AAs with those of ORNs obtained in our previous study. A large number of past studies have focused either on odorant responses in the OE or on odorant-induced responses in the OB. However, a thorough comparison of odorant-induced responses of both stages, ORNs and glomeruli of the same species is as yet lacking. The glomerular response profiles reported herein markedly differ from the previously obtained response profiles of ORNs in that glomeruli clearly have narrower selectivity profiles than ORNs. We discuss possible explanations for the different selectivity profiles of glomeruli and ORNs in the context of the development of the olfactory map.
脊椎动物嗅球（OB）中的肾小球呈现为解剖学上离散的模块，通过嗅觉受体神经元（ORN）的轴突直接接收来自嗅觉上皮（OE）的输入。最近已经确定并分析了大量非洲爪蟾幼体中ORN对氨基酸（AA）的反应谱。在此，我们报告了在相同发育阶段的同一物种的鼻脑制备物中进行的Ca(2+)成像实验。我们记录了OB中肾小球对AA的反应，并确定了单个肾小球对AA的反应谱。我们描述了对AA有反应的肾小球的一般特征，并将它们对AA的反应谱与我们之前研究中获得的ORN的反应谱进行了比较。过去大量的研究要么集中在OE中的气味反应，要么集中在OB中的气味诱导反应。然而，目前还缺乏对同一物种的ORN和肾小球这两个阶段的气味诱导反应进行全面比较。本文报道的肾小球反应谱与先前获得的ORN反应谱明显不同，因为肾小球的选择性谱明显比ORN窄。我们在嗅觉图谱发育的背景下讨论了肾小球和ORN不同选择性谱的可能解释。
