Asynchronous recruitment of low-threshold motor units during repetitive, low-current stimulation of the human tibial nerve.
Asynchronous recruitment of low-threshold motor units during repetitive, low-current stimulation of the human tibial nerve.
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DOI：
10.3389/fnhum.2014.01002
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发表时间：
2014
影响因子：
2.9
通讯作者：
Collins DF
中科院分区：
文献类型：
--
作者：
Dean JC;Clair-Auger JM;Lagerquist O;Collins DF
运动神经元从下行和反射通路接受一连串的输入。我们对这些输入如何转化为人类运动输出的理解，很大程度上来自对自愿收缩过程中单个运动单位的记录。然而，这种方法是有限的，因为输入定义不明确。在这里，我们量化比目鱼肌运动单位的放电，以响应明确定义的以生理相关频率传递的传入输入序列。恒频刺激胫神经(10~100赫兹，30例S)，单次脉冲诱发M波或H反射阈值以下，7/9例受试者募集运动单位。在刺激时招募的所有25个运动单位也是在弱(<；10%MVC)自愿收缩时招募的。在较短的潜伏期(10赫兹时S 19.4±9.4；100赫兹时S 4.1±4.0)下，高频组招募的单位数比低频组多(n=3/25；n=25/25)。当第二个单位被招募时，已经活跃的单位的放电没有改变，这表明招募并不是由于突触驱动的增加。募集后，20赫兹(7.8赫兹)刺激时的平均放电频率低于30赫兹(8.6赫兹)和40赫兹(8.4赫兹)刺激时的平均放电频率。放电在很大程度上与刺激脉冲不同步，“时间锁定”放电发生在H反射潜伏期，概率仅为24%。在89%的试验中，运动单位在刺激停止后继续放电，尽管频率(5.8赫兹)低于刺激期间(7.9赫兹)。本工作支持重复刺激诱发的传入抽射通过整合突触驱动和运动神经元的固有特性来招募运动单位，从而导致符合Henneman的大小原则的生理性招募，从而导致相对较低的放电率和不同步的放电。
Motoneurons receive a barrage of inputs from descending and reflex pathways. Much of our understanding about how these inputs are transformed into motor output in humans has come from recordings of single motor units during voluntary contractions. This approach, however, is limited because the input is ill-defined. Herein, we quantify the discharge of soleus motor units in response to well-defined trains of afferent input delivered at physiologically-relevant frequencies. Constant frequency stimulation of the tibial nerve (10–100 Hz for 30 s), below threshold for eliciting M-waves or H-reflexes with a single pulse, recruited motor units in 7/9 subjects. All 25 motor units recruited during stimulation were also recruited during weak (<10% MVC) voluntary contractions. Higher frequencies recruited more units (n = 3/25 at 10 Hz; n = 25/25 at 100 Hz) at shorter latencies (19.4 ± 9.4 s at 10 Hz; 4.1 ± 4.0 s at 100 Hz) than lower frequencies. When a second unit was recruited, the discharge of the already active unit did not change, suggesting that recruitment was not due to increased synaptic drive. After recruitment, mean discharge rate during stimulation at 20 Hz (7.8 Hz) was lower than during 30 Hz (8.6 Hz) and 40 Hz (8.4 Hz) stimulation. Discharge was largely asynchronous from the stimulus pulses with “time-locked” discharge occurring at an H-reflex latency with only a 24% probability. Motor units continued to discharge after cessation of the stimulation in 89% of trials, although at a lower rate (5.8 Hz) than during the stimulation (7.9 Hz). This work supports the idea that the afferent volley evoked by repetitive stimulation recruits motor units through the integration of synaptic drive and intrinsic properties of motoneurons, resulting in “physiological” recruitment which adheres to Henneman’s size principle and results in relatively low discharge rates and asynchronous firing.
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影响因子：
5.3
作者：
Collins, DF;Burke, D;Gandevia, SC
通讯作者：
Gandevia, SC
影响因子：
11
作者：
DEGAIL, P;LANCE, JW;NEILSON, PD
通讯作者：
NEILSON, PD
DOI：
10.1139/h05-127
发表时间：
2005-06-01
期刊：
CANADIAN JOURNAL OF APPLIED PHYSIOLOGY-REVUE CANADIENNE DE PHYSIOLOGIE APPLIQUEE
影响因子：
--
作者：
Gardiner, P;Beaumont, E;Cormery, B
通讯作者：
Cormery, B
影响因子：
2.5
作者：
Gorassini, MA;Bennett, DJ;Yang, JF
通讯作者：
Yang, JF
影响因子：
2.5
作者：
BELLEMARE, F;WOODS, JJ;BIGLANDRITCHIE, B
通讯作者：
BIGLANDRITCHIE, B