Devor M, Merrill E G, Wall P D
J Physiol. 1977 Sep;270(2):519-31. doi: 10.1113/jphysiol.1977.sp011966.
Experiments were carried out to find if there were post-synaptic effects produced by impulses in the long ranging primary afferents, which had been shown by Wall & Werman (1976) to extend from upper lumbar dorsal roots to the sacral segments. Dorsal rootlets were stimulated in decerebrate low-spinal adult cats.1. The dorsal root potential and ventral root reflex were recorded on S1 root filaments, in response to stimulation of dorsal rootlets extending from L1 to S1. With increasing distance between stimulating and recording segments, these potentials became smaller and more delayed. In two animals, there was no response at S1 to stimulation of L1 and L2 dorsal roots.2. In all animals, stimulation of L3 or L4 dorsal roots produced cell responses in dorsal horn segments L7 or S1. The density of such cells was variable, from animal to animal. Responding cells were mainly concentrated laterally in the dorsal horn.3. The latency and response variability of L7-S1, dorsal horn cells to L3-L4 stimulation was consistent with at least some of them being fired monosynaptically.4. Cells that respond to stimulation of one distant rootlet respond to many closer rootlets as well.5. The receptive fields of L7-S1 dorsal horn cells, responsive to stimulation of L3-L4 rootlets, were typical of those generally found in the L7-S1 segments, and were at some distance from the L4 dermatome. Only twenty cells had receptive fields which extended into the dermatome of the rootlets stimulated.6. It was established that some L4 cells respond to S1 dorsal root stimulation, just as the main study had shown that S1 responds to L4.7. It is concluded that substantial numbers of dorsal horn cells, including cells with many types of cutaneous receptive field, respond to two classes of synaptic in-put: one effective in firing the cell upon natural cutaneous stimulation, and one relatively ineffective, capable of driving the cell only when stimulated electrically and thus carrying a synchronous volley from a number of highly convergent axons. The contribution of this secondary afferent channel to normal and pathological cord physiology has now to be determined.
开展了一些实验，以探究长距离初级传入神经冲动是否会产生突触后效应，Wall和Werman（1976年）已证实这些神经冲动从腰上部背根延伸至骶段。在去大脑的成年低脊髓猫身上刺激背根小支。
记录S1神经根丝上的背根电位和腹根反射，以响应从L1延伸至S1的背根小支的刺激。随着刺激节段与记录节段之间距离的增加，这些电位变得更小且延迟更久。在两只动物中，刺激L1和L2背根时，S1无反应。
在所有动物中，刺激L3或L4背根会在L7或S1背角节段产生细胞反应。此类细胞的密度因动物而异。反应性细胞主要集中在背角的外侧。
L7 - S1背角细胞对L3 - L4刺激的潜伏期和反应变异性表明，其中至少有一些细胞是通过单突触放电的。
对一个远距离背根小支刺激有反应的细胞，对许多更近的背根小支刺激也有反应。
对L3 - L4背根小支刺激有反应的L7 - S1背角细胞的感受野，是L7 - S1节段中通常发现的典型感受野，且与L4皮节有一定距离。只有20个细胞的感受野延伸至所刺激背根小支的皮节。
已证实一些L4细胞对S1背根刺激有反应，正如主要研究表明S1对L4有反应一样。
得出的结论是，大量背角细胞，包括具有多种类型皮肤感受野的细胞，对两类突触输入有反应：一类在自然皮肤刺激时能有效激发细胞放电，另一类相对无效，只有在电刺激时才能驱动细胞，因此携带来自许多高度汇聚轴突的同步冲动。现在必须确定这种次级传入通道对正常和病理脊髓生理学的贡献。
