Martin Wessendorf, Ph.D. Assistant Professor, Department of Neuroscience E-mail: martinw@umn.edu

Research Interests:

The focus of the research in my laboratory is on the neuroanatomical circuitry underlying pain modulation. The sensation of pain is modulated at several sites including the spinal cord and the brainstem. Physiological studies suggest that neurons in the brainstem containing inhibitory neurotransmitters have axons that descend to the spinal cord, inhibiting spinal neurons that relay pain to the brain. However, in addition, there is evidence that excitatory neurons in the same region can facilitate pain, producing (for instance) phantom limb pain and other types of neuropathic pain.  We currently are attempting to identify those neurons responsible.  In our studies, we localize brainstem neurons that project axons to the dorsal spinal cord using spinal injections of fluorescent dyes. We then use multi-color fluorescence microscopy (including confocal microscopy) to identify spinally projecting neurons that express various excitatory neurotransmitters. We also are recording from spinal neurons to test whether these neurotransmitters are responsible for facilitating pain.  In this way, we hope to expand our understanding of the means by which pain is worsened--and, we hope, controlled.  

In addition to our work on pain, we also have worked extensively on developing multi-color fluorescence microscopy as a research tool, and on developing optical microscopic methods such as confocal microscopy and digital deconvolution.

Selected Publications:

(For a comprehensive list of recent publications, refer to PubMed, a service provided by the National Library of Medicine.)

Marinelli S, Connor M, Schnell SA, Christie MJ, Wessendorf MW, Vaughan CW. delta-opioid receptor-mediated actions on rostral ventromedial medulla neurons. Neuroscience. 2005;132(2):239-44.

Marinelli S, Schnell SA, Hack SP, Christie MJ, Wessendorf MW, Vaughan CW. Serotonergic and nonserotonergic dorsal raphe neurons are pharmacologically and electrophysiologically heterogeneous. J Neurophysiol. 2004 Dec;92(6):3532-7.

Wessendorf MW, Wang H, Schnell SA.   Statistical methods for in situ hybridization: identification of autoradiographically labelled cells and structures. J Microsc. 2004 Jul;215(Pt 1):50-61.

Schnell SA, Wessendorf MW. Expression of MOR1C-like mu-opioid receptor mRNA in rats. J Comp Neurol. 2004 May 24;473(2):213-32.

Brelje TC, Wessendorf MW, Sorenson RL. Multicolor laser scanning confocal immunofluorescence microscopy: practical application and limitations. Methods Cell Biol. 2002;70:165-244.

Marinelli S, Vaughan CW, Schnell SA, Wessendorf MW, Christie MJ. Rostral ventromedial medulla neurons that project to the spinal cord express multiple opioid receptor phenotypes. J Neurosci. 2002 Dec 15;22(24):10847-55.

Current Graduate Students:

Heather Leong (Neuroscience, University of Minnesota).

Former Graduate Students:

Ming Gu (Ph.D. 2007, Neuroscience, University of Minnesota).

Wei Wu (Ph.D.). Currently at the Howard Hughes Research Institute, University of California-San Diego, La Jolla, CA

Sara Tallaksen-Greene (Ph.D.). Currently at the Department of Neurology, Univ. of Michigan, Ann Arbor