Functional organization of motor networks in the lumbosacral spinal cord of non-human primates

Amirali Toossi,Steve I Perlmutter,Vivian K Mushahwar,Dirk G Everaert

doi:10.1038/s41598-019-49328-1

Abstract

Implantable spinal-cord-neuroprostheses aiming to restore standing and walking after paralysis have been extensively studied in animal models (mainly cats) and have shown promising outcomes. This study aimed to take a critical step along the clinical translation path of these neuroprostheses, and investigated the organization of the neural networks targeted by these implants in a non-human primate. This was accomplished by advancing a microelectrode into various locations of the lumbar enlargement of the spinal cord, targeting the ventral horn of the gray matter. Microstimulation in these locations produced a variety of functional movements in the hindlimb. The resulting functional map of the spinal cord in monkeys was found to have a similar overall organization along the length of the spinal cord to that in cats. This suggests that the human spinal cord may also be organized similarly. The obtained spinal cord maps in monkeys provide important knowledge that will guide the very first testing of these implants in humans.

Highlights

Recent advances in neuroprostheses have motivated a new wave of technologies aiming to augment the human body or restore its lost functions[1,2,3]
This knowledge was derived from investigations of the movements evoked by intraspinal microstimulation (ISMS) in various parts of the ventral horn along the length of the lumbosacral enlargement, which led to the formation of a functional map[20]
Anesthetized animals are a suitable model of a spinal cord with a complete injury and diminished descending input, and provide a relevant model for testing of ISMS since that the primary intended purpose of ISMS implants is to restore mobility after severe spinal cord injury (SCI)

Summary

Introduction

Recent advances in neuroprostheses have motivated a new wave of technologies aiming to augment the human body or restore its lost functions[1,2,3]. Placement of ISMS electrode arrays in this species is guided by knowledge of the functional organization of the motor networks in the spinal cord[5,20,21]. This knowledge was derived from investigations of the movements evoked by ISMS in various parts of the ventral horn along the length of the lumbosacral enlargement, which led to the formation of a functional map[20]. This study allowed us, for the first time, to identify empirically the functional connectivity of motor networks in the primate lumbosacral cord with a high spatial resolution

Objectives

Methods

Conclusion