Willis W D, Gerhart K D, Willcockson W S, Yezierski R P, Wilcox T K, Cargill C L
J Neurophysiol. 1984 Mar;51(3):467-80. doi: 10.1152/jn.1984.51.3.467.
Recordings were made from 132 raphe- and reticulospinal tract neurons in the medial part of the lower brain stem in 32 anesthetized monkeys. Recording sites were in the nucleus raphe magnus, the rostral nucleus raphe obscurus, and the reticular formation adjacent to the raphe. The neurons were identified by antidromic activation from the upper lumbar spinal cord. Of the population sampled, 83 cells were activated antidromically from the left dorsal lateral funiculus (DLF), 32 from the right DLF, and 17 from both sides. The mean latency for antidromic activation was 8.2 +/- 7.1 ms, corresponding to a mean conduction velocity of 22.8 m/s. No conduction velocities characteristic of unmyelinated axons were observed. Collision tests indicated that raphe-spinal axons that bifurcated to descend in both DLFs branched within the spinal cord. The effects of stimulation in the periaqueductal gray (PAG) or adjacent midbrain reticular formation were tested on 102 spinally projecting neurons in the medial medulla. Of these, 60 cells were excited, 9 cells were inhibited, 8 showed mixed excitation and inhibition, and 25 cells were unaffected. The mean latency for excitation was 11.6 ms and for inhibition, 17.8 ms. Threshold for excitation of raphe- and reticulospinal neurons ranged from 50 to 400 microA. Raphe- and reticulospinal tract cells could often (31/46 cells tested) be excited following stimulation in the ventral posterior lateral nucleus of the thalamus. The mean latency of excitation was 35.6 ms (range, 6-112 ms). Receptive fields could be demonstrated for 80 raphe- and reticulospinal cells, while 48 neurons possessed no demonstrable cutaneous receptive field. Most cells had large excitatory receptive fields, often encompassing the surface of the entire body and face. Some neurons had complex excitatory and inhibitory receptive fields, whereas other cells had large inhibitory receptive fields over much of the surface of the body and face. For most cells (52/55) with excitatory receptive fields, the only effective stimuli were noxious mechanical or noxious heat stimuli. Nonnoxious mechanical stimuli, such as brushing the skin, were capable of activating only a few (3/55) raphe- and reticulospinal neurons, and these were more effectively excited by noxious stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)
在32只麻醉猴的下脑干内侧部位，对132个中缝脊髓束和网状脊髓束神经元进行了记录。记录部位位于中缝大核、中缝隐核头端以及中缝附近的网状结构。通过来自腰髓上段的逆向激活来识别这些神经元。在抽样的神经元群体中，83个细胞可被左侧背外侧索（DLF）逆向激活，32个可被右侧DLF逆向激活，17个可被双侧逆向激活。逆向激活的平均潜伏期为8.2±7.1毫秒，对应平均传导速度为22.8米/秒。未观察到无髓鞘轴突特有的传导速度。碰撞试验表明，分叉后在双侧DLF下行的中缝脊髓轴突在脊髓内分支。对延髓内侧102个向脊髓投射的神经元，测试了导水管周围灰质（PAG）或相邻中脑网状结构刺激的影响。其中，60个细胞被兴奋，9个细胞被抑制，8个表现出混合性兴奋和抑制，25个细胞未受影响。兴奋的平均潜伏期为11.6毫秒，抑制的平均潜伏期为17.8毫秒。中缝和网状脊髓神经元的兴奋阈值为50至400微安。在丘脑腹后外侧核刺激后，中缝和网状脊髓束细胞常常（46个测试细胞中的31个）可被兴奋。兴奋的平均潜伏期为35.6毫秒（范围为6至112毫秒）。80个中缝和网状脊髓细胞可显示感受野，而48个神经元没有可证实的皮肤感受野。大多数细胞具有大的兴奋性感受野，常常覆盖整个身体和面部表面。一些神经元具有复杂的兴奋性和抑制性感受野，而其他细胞在身体和面部大部分表面具有大的抑制性感受野。对于大多数具有兴奋性感受野的细胞（55个中的52个），唯一有效的刺激是有害的机械刺激或有害的热刺激。无害的机械刺激，如轻刷皮肤，仅能激活少数（55个中的3个）中缝和网状脊髓神经元，并且这些神经元被有害刺激更有效地兴奋。（摘要截断于400字）
