Tiling and somatotopic alignment of mammalian low-threshold mechanoreceptors
Tiling and somatotopic alignment of mammalian low-threshold mechanoreceptors
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DOI：
10.1073/pnas.1901378116
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发表时间：
2019-05-07
影响因子：
11.1
通讯作者：
Ginty, David D.
中科院分区：
文献类型：
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作者：
Kuehn, Emily D.;Meltzer, Shan;Ginty, David D.
作用于皮肤的无害机械刺激由感觉神经元检测，称为低阈值机械感受器(LTMR)。LTMR根据其反应特性、动作电位传导速度、对皮肤静态压痕的适应率和末端解剖进行分类。在这里，我们报告了五种主要的毛状皮肤LTMR亚型的皮肤和中央轴突投射的组织特性。我们发现，特定LTMR类神经元的轴突相对于其皮肤末端器官(例如毛囊)基本上是不重叠的，Aβ快速适应-LTMR是唯一的例外。每个LTMR类型的单个神经元相对于其相关的毛囊大多是不重叠的，值得注意的例外是C-LTMR，它表现出多个分支，冗余地支配单个毛囊。在脊髓，LTMR中央投射与皮肤神经支配模式相比，表现为肩尾延长和内侧受压，这些中央投射也显示出良好的同型地形邻接程度。因此，这些发现揭示了LTMR亚型轴突投射在多毛皮肤中的同型平铺和脊髓轴突终末模式的显著空间精度，表明机械感觉背角具有体感精确的触觉编码能力。
Innocuous mechanical stimuli acting on the skin are detected by sensory neurons, known as low-threshold mechanoreceptors (LTMRs). LTMRs are classified based on their response properties, action potential conduction velocity, rate of adaptation to static indentation of the skin, and terminal anatomy. Here, we report organizational properties of the cutaneous and central axonal projections of the five principal hairy skin LTMR subtypes. We find that axons of neurons within a particular LTMR class are largely nonoverlapping with respect to their cutaneous end organs (e.g., hair follicles), with A beta rapidly adapting-LTMRs being the sole exception. Individual neurons of each LTMR class are mostly nonoverlapping with respect to their associated hair follicles, with the notable exception of C-LTMRs, which exhibit multiple branches that redundantly innervate individual hair follicles. In the spinal cord, LTMR central projections exhibit rostrocaudal elongation and mediolateral compression, compared with their cutaneous innervation patterns, and these central projections also exhibit a fine degree of homotypic topographic adjacency. These findings thus reveal homotypic tiling of LTMR subtype axonal projections in hairy skin and a remarkable degree of spatial precision of spinal cord axonal termination patterns, suggesting a somatotopically precise tactile encoding capability of the mechanosensory dorsal horn.