Senn W, Wyler K, Clamann H P, Kleinle J, Lüscher H R, Müller L
Institut für Informatik und angewandte Mathematik, Universität Bern, Switzerland.
Biol Cybern. 1997 Jan;76(1):11-22. doi: 10.1007/s004220050317.
The motor units of a skeletal muscle may be recruited according to different strategies. From all possible recruitment strategies nature selected the simplest one: in most actions of vertebrate skeletal muscles the recruitment of its motor units is by increasing size. This so-called size principle permits a high precision in muscle force generation since small muscle forces are produced exclusively by small motor units. Larger motor units are activated only if the total muscle force has already reached certain critical levels. We show that this recruitment by size is not only optimal in precision but also optimal in an information theoretical sense. We consider the motoneuron pool as an encoder generating a parallel binary code from a common input to that pool. The generated motoneuron code is sent down through the motoneuron axons to the muscle. We establish that an optimization of this motoneuron code with respect to its information content is equivalent to the recruitment of motor units by size. Moreover, maximal information content of the motoneuron code is equivalent to a minimal expected error in muscle force generation.
骨骼肌的运动单位可根据不同策略进行募集。在所有可能的募集策略中，自然选择了最简单的一种：在脊椎动物骨骼肌的大多数动作中，其运动单位的募集是按照大小顺序进行的。这种所谓的大小原则使得肌肉力量产生具有高精度，因为小肌肉力量仅由小运动单位产生。只有当总肌肉力量已经达到一定临界水平时，更大的运动单位才会被激活。我们表明，这种按大小募集不仅在精度上是最优的，而且在信息理论意义上也是最优的。我们将运动神经元池视为一个编码器，它从该池的共同输入生成并行二进制代码。生成的运动神经元代码通过运动神经元轴突向下发送到肌肉。我们确定，对该运动神经元代码的信息内容进行优化等同于按大小募集运动单位。此外，运动神经元代码的最大信息内容等同于肌肉力量产生中的最小预期误差。
