Scalable Optogenetic Modulation of Pain: A Novel Implant for Nociceptive Stimulation of the Sciatic Nerve

The number of Americans that currently live with chronic pain is estimated to be greater than 30% of the entire population (Volkow & McLellan, 2016). The development of chronic pain is known to play a role in increasing the risk for substance use disorders, anxiety, and depression (Tetsunaga 2018). Knowing this, it is imperative to elucidate the changes that occur in the brain as pain transitions from acute to chronic, how the intensity of pain affects neuronal plasticity, and how areas of the brain that control positive and negative outcomes as well as emotion and mood are affected by chronic pain. To help answer this question, we have created a novel, implantable nerve cuff capable producing a range of pain intensities when combined with optogenetic technologies. Further we have validated the utility of this nerve cuff by optogenetically stimulating peripheral pain sensing neurons (i.e., nociceptors) following an injection of the light-sensitive protein channelrhodopsin into the sciatic nerve. We predict that future in vivo testing will demonstrate the scalable delivery of nociceptive stimuli and hope that this device can be used in future studies examining the transition from acute to chronic pain.