走路和跑步，谁说了算？近日，Nature发表了题为Midbrain circuits that set locomotor speed and gait selection的文章。该文章研究了中脑楔形核（Cuneiform Nucleus，CnF）和脚桥核（pedunculo pontine nucleus，PPN）相关功能。CnF和PPN的神经元都能启动位移，但只有CnF能引起高速度的位移活动，相反PPN神经元更青睐慢速运动。也就是说PPN神经元对多控制走路，而CnF神经元则在跑步中扮演了重要角色。具体细节见全文（https://www.nature.com/articles/nature25448）。

Locomotionis a fundamental motor function common to the animal kingdom. It is implemented episodically and adapted to behavioural needs, including exploration, which requires slow locomotion, and escape behaviour, which necessitates fasterspeeds. The control of these functions originates in brain stem structures, although the neuronal substrate (s) that support them have not yet been elucidated. Here we show in mice that speed and gait selection are controlled by glutamatergic excitatory neurons (GlutNs) segregated in two distinct midbrain nuclei: the cuneiform nucleus (CnF) and the pedunculopontine nucleus (PPN). GlutNs in both of these regions contribute to the control of slower, alternating-gait locomotion, whereas only GlutNs in the CnF are able to elicit high-speed, synchronous-gait locomotion. Additionally, both the activation dynamics and the input and output connectivity matrices of GlutNs in the PPN and the CnF support explorative and escape locomotion, respectively. Our results identify two regions in the midbrain that act in conjunction to select context-dependent locomotor behaviours.