1. Lexington Veterans’ Affairs Healthcare System , Lexington, KY 40502 , USA
2. Department of Physiology, University of Kentucky , Lexington, KY 40536 , USA
3. Spinal Cord and Brain Injury Research Center, University of Kentucky , Lexington, KY 40536 , USA
4. Department of Neuroscience, University of Kentucky , Lexington, KY 40536 , USA
5. Department of Anesthesiology and Critical Care Medicine, Children’s Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA 19104 , USA