Nature vol 553, pages 455–460 (25 January 2018)
Midbrain circuits that set locomotor speed and gait
Caggiano, R. Leiras, H. Goñi-Erro, D. Masini, C. Bellardita, J. Bouvier, V.
Caldeira, G. Fisone & O. Kiehn
is 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 faster
speeds. The control of these functions originates in brainstem 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.