Optogenetic regulation of peripheral sensory or motor axons during chick embryogenesis

Abstract

Our goal is to understand the effects of altered embryonic movement and sensation on proper neural development. Previously, we have shown in chick embryos that persistent expression of channelrhodopsin in peripheral axons of the leg can be achieved via electroporation of a modified transposon‐based exrpression system and that illumination of the leg with a blue LED can activate leg movements and modulate spontaneous leg motility. We now extend this work to include the ability to achieve persistent expression in targeted neuronal populations including peripheral sensory or motor axons by controlling the age of the embryo electroporated and the directionality of the applied current field. Also, we have developed an inexpensive system for focusing light from brighter LEDs to confine illumination to selected nerves and to activate them at later stages of development as superficial tissues thicken. This allows us to assay the effects of selective activation of sensory or motor axons in specific nerves in the leg. Lastly, we are testing transposon‐based expression of Arch and Halorhodopsin in chick embryos for the ability to suppress excitation in peripheral nerves.