Surgical implantation of wireless, battery-free optoelectronic epidural implants for optogenetic manipulation of spinal cord circuits in mice

This protocol describes the surgical procedures for implantation of a wireless, battery-free optogenetic implant (NeuroLux spinal optogenetic device) for optogenetic control of spinal cord circuits in mice. The use of optogenetics to regulate neuronal activity has revolutionized the study of the neural circuitry underlying a number of complex behaviors in rodents. Advances have been particularly evident in the study of brain circuitry and related behaviors, while advances in the study of spinal circuitry have been less striking because of technical hurdles. We have developed and characterized a wireless and fully implantable optoelectronic device that enables optical manipulation of spinal cord circuitry in mice via a microscale light-emitting diode (mu LED) placed in the epidural space (NeuroLux spinal optogenetic device). This protocol describes how to surgically implant the device into the epidural space and then analyze light-induced behavior upon mu LED activation. We detail optimized optical parameters for in vivo stimulation and demonstrate typical behavioral effects of optogenetic activation of nociceptive spinal afferents using this device. This fully wireless spinal mu LED system provides considerable versatility for behavioral assays compared with optogenetic approaches that require tethering of animals, and superior temporal and spatial resolution when compared with other methods used for circuit manipulation such as chemogenetics. The detailed surgical approach and improved functionality of these spinal optoelectronic devices substantially expand the utility of this approach for the study of spinal circuitry and behaviors related to mechanical and thermal sensation, pruriception and nociception. The surgical implantation procedure takes ~1 h. The time required for the study of behaviors that are modulated by the light-activated circuit is variable and will depend upon the nature of the study.

Automated summary

This protocol describes the surgical procedures for implantation of a wireless, battery-free optogenetic implant for controlling spinal cord circuits in mice. The device enables optical manipulation of spinal cord circuitry via a microscale LED and provides versatility for behavioral assays. The improved functionality of these optoelectronic devices expands the utility of this approach for studying spinal circuitry and related behaviors.