Speed and segmentation control mechanisms characterized in rhythmically-active circuits created from spinal neurons produced from genetically-tagged embryonic stem cells.

Matthew J Sternfeld,Martyn Goulding,Samuel L Pfaff,Kathryn L Hilde,Niall J Moore,Kamal Sharma,Neal D Amin,Dario Bonanomi,Shawn P Driscoll,Marito Hayashi,Wesley D Gifford,Matthew T Pankratz,Christopher A Hinckley

doi:10.7554/elife.21540

Abstract

Flexible neural networks, such as the interconnected spinal neurons that control distinct motor actions, can switch their activity to produce different behaviors. Both excitatory (E) and inhibitory (I) spinal neurons are necessary for motor behavior, but the influence of recruiting different ratios of E-to-I cells remains unclear. We constructed synthetic microphysical neural networks, called circuitoids, using precise combinations of spinal neuron subtypes derived from mouse stem cells. Circuitoids of purified excitatory interneurons were sufficient to generate oscillatory bursts with properties similar to in vivo central pattern generators. Inhibitory V1 neurons provided dual layers of regulation within excitatory rhythmogenic networks - they increased the rhythmic burst frequency of excitatory V3 neurons, and segmented excitatory motor neuron activity into sub-networks. Accordingly, the speed and pattern of spinal circuits that underlie complex motor behaviors may be regulated by quantitatively gating the intra-network cellular activity ratio of E-to-I neurons.

Highlights

Many behaviors are based on circuits with flexible activity capable of switching their output (Bargmann and Marder, 2013; Garcia-Campmany et al, 2010)
We isolated four independent embryonic stem (ES) cell lines containing the V1 reporter En1:Cre/tdTomato, two lines with the V2a reporter Chx10:Cre/tdTomato, seven lines with the V3 reporter Sim1:Cre/tdTomato, and two lines with the motor neuron reporter tgHb9-GFP (Figure 1A). These ES cell lines were differentiated into neurospheres containing ~50,000 aggregated cells using retinoic acid (RA) and smoothened agonist (SAG)
Unpaired t test: *p

Summary

Introduction

Many behaviors are based on circuits with flexible activity capable of switching their output (Bargmann and Marder, 2013; Garcia-Campmany et al, 2010). Connectomes and functional roles for the neuronal subtypes that comprise circuits have begun to be defined, the output of large multicellular networks are difficult to predict from the input pattern because the mechanisms that coordinate and regulate these complex systems remain poorly understood. Cell Biology Neuroscience eLife digest The nerve cells or neurons within an animal’s nervous system connect with one another like the wires in a complex circuit. Each neuron can send and receive signals and a major challenge in neuroscience is to understand how these circuits of neurons behave. Researchers often use genetic tools and computer modeling to map the connections between the cells in a nervous system. It remains difficult to predict how an input signal will appear at the output after it passes through a network made of different types of neuron

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