National Centre for Biological Sciences, Bangalore, India.
Adv Neurobiol. 2022;28:169-190. doi: 10.1007/978-3-031-07167-6_8.
Beginning about half a century ago, the rules that determine how motor units are recruited during movement have been deduced. These classical experiments led to the formulation of the 'size principle'. It is now clear that motoneuronal size is not the only indicator of recruitment order. In fact, motoneuronal passive, active and synaptic conductances are carefully tuned to achieve sequential recruitment. More recent studies, over the last decade or so, show that the premotor circuitry is also functionally specialized and differentially recruited. Modular sub networks of interneurons and their post-synaptic motoneurons have been shown to drive movements with varying intensities. In addition, these modular networks are under the influence of neuromodulators, which are capable of acting upon multiple motor and premotor targets, thereby altering behavioral outcomes. We discuss the recruitment patterns of motoneurons in light of these new and exciting studies.
大约从半个世纪前开始，人们就已经推导出了决定运动中运动单位如何被募集的规则。这些经典实验导致了“大小原则”的提出。现在很清楚，运动神经元的大小并不是募集顺序的唯一指标。事实上，运动神经元的被动、主动和突触电导率都被精心调整，以实现顺序募集。在过去的十年左右的时间里，最近的研究表明，运动前电路也具有功能专门化和差异募集的特点。已经证明，中间神经元及其突触后的运动神经元的模块化子网可以驱动不同强度的运动。此外，这些模块化网络受到神经调质的影响，神经调质能够作用于多个运动和运动前目标，从而改变行为结果。我们根据这些新的令人兴奋的研究讨论了运动神经元的募集模式。
