Search Neuroscience

Steve Davidson Ph.D. 2009 E-mail: davi1082@umn.edu

Undergraduate Institution and Major/Degree:

Major Advisor(s):

Research Description:

To protect the integrity of an organism a somatosensory system has evolved to respond to noxious stimuli. A critical component of this system in vertebrates is the neurons in the spinal cord which receive information from the periphery, integrate, and then distribute that information to supraspinal sites. Our research describes the function and hodology of these cells.

We have made several interesting and novel observations regarding the possible contributions of these cells to itch and pain:

1. Pruriceptive primate spinothalamic tract neurons respond either to histamine or to cowhage, a non-histaminergic pruritogen, suggesting multiple independent paths in the CNS for itch processing.

2. Scratching the receptive field of a spinothalamic tract neuron during a response to histamine produces inhibition, suggesting that part of the mechanism for relief from itch that is produced by scratching exists at the level of the spinal cord.

3. Spinal neurons that respond to itch producing agents send axons to several nuclei within the ventral posterior and posterior regions of the thalamus, indicating a target region of the brain that could be important for itch processing.

4. Spinothalamic tract neurons that respond to itch producing agents also respond to various other noxious stimuli such as heat, pinch, and the painful chemical capsaicin, indicating that these cells could play multiple roles in sensation.

Given the importance of the spinothalamic tract in transmitting information about pain, thermal sensation, and itch to the brain we have become interested in the development of this pathway during the fetal and the neonatal periods. To address questions about the genesis of the spinothalamic tract we have developed a simple technique permitting the injection of neural tracers into specific brain regions of fetal and neonatal mice in vivo. We have recently established that the gross structure of the spinothalamic tract is complete by the time of birth, however whether synaptic or functional connections are made is still unknown. We are also currently working to determine whether specific genes expressed in the spinal cord during development contribute to the differentiation of spinothalamic tract neurons.

Selected Publications and Presentations:

S Davidson, X Zhang, SG Khasabov, DA Simone, GJ Giesler Jr (2008) Termination zones of functionally characterized primate spinothalamic tract neurons in posterior thalamus. J Neurophysiol 100:2026-37

S Davidson and GJ Giesler. “Ascending Pathways.” Chapter in: Binder, M.D.; Hirokawa, N.; Windhorst, U.; Hirsch, M.C. (Eds.) Encyclopedia of Neuroscience, Springer, 2008.

S Davidson, X Zhang, SG Khasabov, DA Simone, GJ Giesler Jr. (2007). Responses of monkey spinothalamic tract neurons to itch-producing and itch-inhibiting stimuli. Acta Dermato-venereologica 87:475.

S Davidson, X Zhang, CH Yoon, SG Khasabov, DA Simone, GJ Giesler Jr (2007) The itch-producing agents histamine and cowhage activate separate populations of primate spinothalamic tract neurons. J Neurosci 27:10007-14.

X Zhang, S Davidson, GJ Giesler (2006) Thermally identified subgroups of marginal zone neurons project to distinct regions of the ventral posterior nucleus in rats. J Neurosci 26:5215-5223.

Honors and Awards:

Professional Memberships:

• American Association for the Advancement of Science (2007-)

• American Physiological Society (2008-)

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