Baier H, Rotter S, Korsching S
Department of Physical Biology, Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
Proc Natl Acad Sci U S A. 1994 Nov 22;91(24):11646-50. doi: 10.1073/pnas.91.24.11646.
It is unknown how neuronal connections are specified in the olfactory system. To define rules of connectivity in this system, we investigated whether the projection of sensory neurons from the olfactory epithelium to the olfactory bulb is topographically ordered. By backtracking with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI), we find that neurons projecting into a single identified glomerulus are widely dispersed over the olfactory epithelium. Their positions in the sensory surface do not predict their glomerulus specificity and are probably random. A statistical analysis reveals that neurons connected to the same glomerulus are spaced at distances of several cell diameters from each other. The convergence of projections to one point in the target area from neurons that are widely and evenly distributed in the sensory surface constitutes an unusual type of connectional topography that contrasts with the precise topological (neighborhood-preserving) maps found in other sensory systems. It may maximize the probability to detect odorants that activate a single glomerular unit.
目前尚不清楚嗅觉系统中神经元连接是如何确定的。为了定义该系统中的连接规则，我们研究了嗅觉上皮的感觉神经元向嗅球的投射是否按拓扑顺序排列。通过用高氯酸1,1'-二十八烷基-3,3,3',3'-四甲基吲哚羰花青（DiI）进行逆向追踪，我们发现投射到单个已确定肾小球的神经元广泛分布在嗅觉上皮上。它们在感觉表面的位置并不能预测其肾小球特异性，可能是随机的。统计分析表明，连接到同一肾小球的神经元彼此间隔几个细胞直径的距离。从在感觉表面广泛且均匀分布的神经元向目标区域中的一个点的投射汇聚构成了一种不寻常的连接拓扑类型，这与在其他感觉系统中发现的精确拓扑（保持邻域）图形成对比。它可能会使检测激活单个肾小球单位的气味剂的概率最大化。
