Fast kinetics, high-frequency oscillations, and subprimary firing range in adult mouse spinal motoneurons.
Fast kinetics, high-frequency oscillations, and subprimary firing range in adult mouse spinal motoneurons.
复制标题
DOI：
10.1523/jneurosci.3260-09.2009
复制
发表时间：
2009-09-09
期刊：
影响因子：
--
通讯作者：
Zytnicki D
中科院分区：
文献类型：
--
作者：
Manuel M;Iglesias C;Donnet M;Leroy F;Heckman CJ;Zytnicki D
小鼠运动单位的快速收缩时间创造了一种独特的情况，即运动神经元必须以低频激发以产生较小的力，但也必须以非常高的频率（比猫或大鼠运动神经元高得多）才能达到其运动单位的融合频率。为了了解如何解决这个问题，我们对成年小鼠脊髓运动神经元进行了细胞内记录，并系统地研究了它们的亚阈值特性和放电模式。我们发现，由于三个显着特征，小鼠运动神经元比猫和大鼠运动神经元具有更广泛的放电频率范围。首先，它们的膜时间常数很短。这导致更高的截止频率和更高的共振频率，从而允许小鼠运动神经元以更高的频率整合输入。其次，他们的 AHP 更快，允许运动神经元以更高的速率放电。第三，运动神经元在峰间间隔期间表现出高频（100-150 Hz）亚阈值振荡。快速的膜动力学极大地有利于这些振荡的出现，从而产生“次初级范围”的发射。在猫和大鼠脊髓运动神经元中从未报道过的这个范围内，振荡遵循 AHP 并在可变延迟后触发尖峰，允许低频放电，但代价是不规则的速率。
The fast contraction time of mouse motor units creates a unique situation where motoneurons have to fire at low frequencies to produce small forces but also at very high frequency (much higher than in cat or rat motoneurons) to reach the fusion frequency of their motor units. To understand how this problem is solved, we performed intracellular recordings of adult mouse spinal motoneurons and investigated systematically their sub-threshold properties and their discharge pattern. We show that mouse motoneurons have a much wider range of firing frequencies than cat and rat motoneurons because of three salient features. First, they have a short membrane time constant. This results in a higher cut off frequency and a higher resonance frequency, which allow mouse motoneurons to integrate inputs at higher frequencies. Second, their AHP is faster allowing the motoneurons to discharge at a higher rate. Third, motoneurons display high frequency (100–150 Hz) sub-threshold oscillations during the interspike intervals. The fast membrane kinetics greatly favors the appearance of these oscillations, creating a "sub-primary range" of firing. In this range, which has never been reported in cat and in rat spinal motoneurons, the oscillations follow the AHP and trigger spiking after a variable delay, allowing a discharge at low frequency but at the expense of an irregular rate.