1 Department of Neurobiology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA; Pittsburgh Center for Pain Research, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA.
2 Department of Neurobiology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA; Pittsburgh Center for Pain Research, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA; Department of Anesthesiology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA. Electronic address: saross@pitt.edu.