Adaptation of cat motoneurons to sustained and intermittent extracellular activation.
Adaptation of cat motoneurons to sustained and intermittent extracellular activation.
复制标题
猫运动神经元对持续和间歇性细胞外激活的适应。
DOI：
10.1113/jphysiol.1993.sp019625
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Stuart,DG
中科院分区：
文献类型：
--
作者：
Spielmann,JM;Laouris,Y;Nordstrom,MA;Robinson,GA;Reinking,RM;Stuart,DG
1.本研究的主要目的是量化脊髓运动神经元的适应持续和间歇性激活，使用刺激电流应用到单个测试细胞的细胞外途径，与细胞内途径相反，如以前所使用的。此外，测试了测试细胞的放电率特性与这些细胞及其运动单位的其他类型（大小）相关特性之间的关联。2.用微电极刺激供应深度麻醉猫的腓肠肌内侧肌的运动神经元240 s，微电极以1.25倍的重复放电阈值通过持续的细胞外电流。在相同的相对刺激强度下，在间歇性1 s电流脉冲（持续时间600 ms）的休息期后，也对许多细胞进行了测试。从受测试神经元支配的运动单元的EMG评估细胞放电。运动神经元及其运动单位根据常规标准分为四类（即FF、FR、S和F型;其中F = FF + FR）。在所有，20 F（16 FF，4 FR）和14 S细胞进行了研究与持续刺激。用间歇刺激研究了这些细胞中的30个（17 F，13 S）和另外两个细胞（1 F，1 S）。3. F和S细胞持续放电>或= 2 s所需的平均阈值电流无显著差异。然而，运动神经元放电的大多数其他测量参数显着不同，这两个细胞组。例如，在1.25倍的重复放电阈值电流下，响应于240 s持续激活的平均放电持续时间为123 +/-88 s（+/-S.D.）F细胞为233 +/-19 s，S细胞为233 +/-19 s。这些值显著长于来自采用细胞内刺激的可比较的先前报道的研究的值。在间歇刺激下，F细胞和S细胞的放电持续时间没有显著差异。4.所有细胞都表现出从电流开始到第一个尖峰的延迟，随后是短暂的加速放电，随后是放电速率的较慢下降。一些细胞（21/34例持续激活; 20/32例间歇性激活）表现出双峰放电（峰间期≤ 10 ms），与更主要的单线放电混合。双联体在S细胞型中更常见。（400字处删节）
1. The main purpose of this study was to quantify the adaptation of spinal motoneurons to sustained and intermittent activation, using an extracellular route of stimulating current application to single test cells, in contrast to an intracellular route, as has been used previously. In addition, associations were tested between firing rate properties of the tested cells and other type (size)‐related properties of these cells and their motor units. 2. Motoneurons supplying the medial gastrocnemius muscle of the deeply anaesthetized cat were stimulated for 240 s with microelectrodes which passed sustained extracellular current at 1.25 times the threshold for repetitive firing. Many cells were also tested following a rest period with intermittent 1 s current pulses (duration 600 ms) at the same relative stimulus strength. Cell discharge was assessed from the EMG of the motor unit innervated by the test neuron. The motoneurons and their motor units were assigned to four categories (i.e. types FF, FR, S and F; where F = FF + FR) based on conventional criteria. In all, twenty F (16 FF, 4 FR) and fourteen S cells were studied with sustained stimulation. Thirty of these cells (17 F, 13 S) and an additional two cells (1 F, 1 S) were studied with intermittent stimulation. 3. The mean threshold current required for sustained firing for a period of > or = 2 s was not significantly different for F and S cells. However, most of the other measured parameters of motoneuron firing differed significantly for these two cell groups. For example, at 1.25 times the threshold current for repetitive firing, the mean firing duration in response to 240 s of sustained activation was 123 +/‐ 88 s (+/‐ S.D.) for F cells vs. 233 +/‐ 19 s for S cells. These values were significantly longer than those from a comparable, previously reported study that employed intracellular stimulation. With intermittent stimulation, the firing durations of F and S cells were not significantly different from each other. 4. All cells exhibited a delay from the onset of current to the first spike, followed by a brief accelerating discharge that was followed by a slower drop in firing rate. Some cells (21 of 34 with sustained activation; 20 of 32 with intermittent) exhibited doublet discharges (interspike intervals < or = 10 ms) that were intermingled with the more predominant singlet discharges. Doublets were more common in the S cell type.(ABSTRACT TRUNCATED AT 400 WORDS)