Sensory Activation of Command Cells for Locomotion and Modulatory Mechanisms: Lessons from Lampreys.

Gheylen Daghfous,Warren W Green,Réjean Dubuc,Barbara S Zielinski,Simon T Alford

doi:10.3389/fncir.2016.00018

Abstract

Sensorimotor transformation is one of the most fundamental and ubiquitous functions of the central nervous system (CNS). Although the general organization of the locomotor neural circuitry is relatively well understood, less is known about its activation by sensory inputs and its modulation. Utilizing the lamprey model, a detailed understanding of sensorimotor integration in vertebrates is emerging. In this article, we explore how the vertebrate CNS integrates sensory signals to generate motor behavior by examining the pathways and neural mechanisms involved in the transformation of cutaneous and olfactory inputs into motor output in the lamprey. We then review how 5-hydroxytryptamine (5-HT) acts on these systems by modulating both sensory inputs and motor output. A comprehensive review of this fundamental topic should provide a useful framework in the fields of motor control, sensorimotor integration and neuromodulation.

Highlights

Locomotion is a rhythmic motor behavior involved in everyday functions
It has been shown in lampreys that the axons of large RS cells make synaptic contacts with several classes of spinal neurons and some are involved in generating locomotion (Rovainen, 1974; Buchanan, 1982; Ohta and Grillner, 1989; for a review of RS pathways in mammals, see Perreault and Glover, 2013)
Local injections of glutamate antagonists in the olfactory bulb (OB) blocked the responses of RS cells to olfactory nerve stimulation, indicating that synaptic transmission between olfactory sensory neurons (OSN) and projection neurons relies on glutamate (Figure 2 in Derjean et al, 2010)

Summary

Introduction

Locomotion is a rhythmic motor behavior involved in everyday functions. It requires the activation and coordination of the axial and/or appendicular musculature. We explore how the vertebrate CNS integrates sensory signals to generate motor behavior by examining the pathways and neural mechanisms involved in the transformation of cutaneous and olfactory inputs into motor output in the lamprey.

Results

Conclusion