Large-Scale Convergence of Receptor Cell Arrays Onto Afferent Terminal Arbors in the Lorenzinian Electroreceptors of Polyodon.
Large-Scale Convergence of Receptor Cell Arrays Onto Afferent Terminal Arbors in the Lorenzinian Electroreceptors of Polyodon.
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DOI：
10.3389/fnana.2020.00050
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发表时间：
2020
影响因子：
2.9
通讯作者：
Neiman LL
中科院分区：
文献类型：
--
作者：
Russell DF;Warnock TC;Zhang W;Rogers DE;Neiman LL
某些感官感受器含有许多感受器，汇聚到少数传入细胞上。收敛创建了迭代并行组织的星形拓扑神经网络，它可能产生特殊的功能特性。我们对成体前白鳍鱼(Polyodon Spathula)嘴上的电感受器的大规模汇聚进行了定量，并分析了汇聚背后的传入终末分支。在神经生理学标测中，记录到的传入神经支配壶腹部器官23.3±9.1(6-45)个，并支配感受野锐界内的每个壶腹部器官。通过成像和建模，每个壶腹器官都含有∼665个洛伦西亚受体细胞。在免疫荧光标记轴突细丝、神经胶质鞘或结节离子通道后，或通过DiI示踪法，我们在电感受器上成像了三种类型的传入分支。(1)有髓树：3.0 8±0.5 1(2-4)个平行的脑神经传入纤维从深部组织进入感受野，然后分支成平行于皮肤的大的有髓树突的板状树，这些树突的径向分支直到∼9肢体的半月节，这是棘波编码者的候选部位。(Ii)向内过渡：每条有髓肢体向远端进入局部的无髓枝，起源于由终末(卫星)胶质细胞覆盖的向内分支结构。无髓过渡区包括4-6微米宽的球形传入模块，从中冒出细小的平行亚微米神经突起，这可能是一种新的神经元分支类型。轴突束形成松散的束状突起，向远端投射∼105微米，支配邻近壶腹器官的局部∼-3群。(3)放射状突起：覆盖在每个壶腹器官基极的感觉神经上皮细胞中的受体细胞由无髓和亚微米的放射状突起的末端支配，在凝集素+基底膜的远侧形成一个薄的曲面板。大量的放射状突起从较粗(∼2微米)的基底外侧干分化而来。总体而言，一个平均的多齿龙电感受器形成了∼9传感器组的星形拓扑阵列。假设100%有神经支配，平均每个传入野的总汇聚率为15,495±6,052个平行受体细胞。大规模融合可能会增加刺激编码成尖峰传入输出的信噪比(SNR)，从而提高接收器灵敏度。无髓鞘乔木也可以再生和修复壶腹器官的传入神经。Lsid：urn:lsid:zoobank.org:act:09BCF04C-3C3C-4B6C-9DC9-A2BF43087369
Certain sensory receptors contain many transducers, converging onto few afferents. Convergence creates star-topology neural networks, of iterative parallel organization, that may yield special functional properties. We quantitated large-scale convergence in electroreceptors on the rostrum of preadult paddlefish, Polyodon spathula (Acipenseriforme vertebrates), and analyzed the afferent terminal branching underlying the convergence. From neurophysiological mapping, a recorded afferent innervated 23.3 ± 9.1 (range 6–45) ampullary organs, and innervated every ampullary organ within the receptive field’s sharp boundary. Ampullary organs each contained ∼665 Lorenzinian receptor cells, from imaging and modeling. We imaged three serial types of afferent branching at electroreceptors, after immunofluorescent labeling for neurite filaments, glial sheaths, or nodal ion channels, or by DiI tracing. (i) Myelinated tree: Each of 3.08 ± 0.51 (2–4) parallel afferents from a cranial nerve (ALLn) entered a receptive field from deeper tissue, then branched into a laminar tree of large myelinated dendrites, parallel to the skin, that branched radially until ∼9 extremities with heminodes, which were candidate sites of spike encoders. (ii) Inline transition: Each myelinated extremity led distally into local unmyelinated arbors originating at inline branching structures covered by terminal (satellite) glia. The unmyelinated transition zones included globular afferent modules, 4–6 microns wide, from which erupted fine fascicles of parallel submicron neurites, a possibly novel type of neuronal branching. The neurite fascicles formed loose bundles projecting ∼105 microns distally to innervate local groups of ∼3 adjacent ampullary organs. (iii) Radial arbors: Receptor cells in an electrosensory neuroepithelium covering the basal pole of each ampullary organ were innervated by bouton endings of radial neurites, unmyelinated and submicron, forming a thin curviplanar lamina distal to the lectin+ basal lamina. The profuse radial neurites diverged from thicker (∼2 micron) basolateral trunks. Overall, an average Polyodon electroreceptor formed a star topology array of ∼9 sensor groups. Total convergence ratios were 15,495 ± 6,052 parallel receptor cells per afferent per mean receptive field, assuming 100% innervation. Large-scale convergence likely increases the signal-to-noise ratio (SNR) of stimulus encoding into spiking afferent output, increasing receiver sensitivity. Unmyelinated arbors may also regenerate and repair the afferent innervation of ampullary organs. LSID: urn:lsid:zoobank.org:act:09BCF04C-3C3C-4B6C-9DC9-A2BF43087369