Excitatory rubral cells encode the acquisition of novel complex motor tasks

Giorgio Rizzi,Mustafa Coban,Kelly R Tan

doi:10.1038/s41467-019-10223-y

Abstract

The red nucleus (RN) is required for limb control, specifically fine motor coordination. There is some evidence for a role of the RN in reaching and grasping, mainly from lesion studies, but results so far have been inconsistent. In addition, the role of RN neurons in such learned motor functions at the level of synaptic transmission has been largely neglected. Here, we show that Vglut2-expressing RN neurons undergo plastic events and encode the optimization of fine movements. RN light-ablation severely impairs reaching and grasping functions while sparing general locomotion. We identify a neuronal population co-expressing Vglut2, PV and C1QL2, which specifically undergoes training-dependent plasticity. Selective chemo-genetic inhibition of these neurons perturbs reaching and grasping skills. Our study highlights the role of the Vglut2-positive rubral population in complex fine motor tasks, with its related plasticity representing an important starting point for the investigation of mechanistic substrates of fine motor coordination training.

Highlights

The red nucleus (RN) is required for limb control, fine motor coordination
The largest cells are generally found within the caudal part, while in the middle and rostral parts of the nucleus, populations of medium-sized and small cells appear[12,13]. These experimental observations are in line with the concept of the large RN magnocellular neurons (RNm) encompassing the caudal portion and the RN parvocellular neurons (RNp) making up the smaller rostral area[14]
A general decrease in all the OFT locomotion parameters was observed, none of them were statistically significant (Fig. 1c–g) suggesting that the bilateral ablation of the RN has a minimal impact on general locomotion

Summary

Introduction

The red nucleus (RN) is required for limb control, fine motor coordination. Variability capture (standard vs high-speed), as well as levels decomposition of reaching movements (approach, extension, supination pronation, arpeggio etc...), have led to different interpretations of the role of the RN in fine motor skills[9,10,11]. The largest cells are generally found within the caudal part, while in the middle and rostral parts of the nucleus, populations of medium-sized and small cells appear[12,13] These experimental observations are in line with the concept of the large RN magnocellular neurons (RNm) encompassing the caudal portion and the RN parvocellular neurons (RNp) making up the smaller rostral area[14]. In a reach-to-grasp task, RNm were proposed to contribute to the control of hand pre-shaping[20]

Methods

Results

Conclusion