Dr. Michael Morgan

Title:	Professor of Psychology
Office Location:	CL 208V
Address:	Washington State University 14204 NE Salmon Creek Ave. Vancouver, WA 98686
Phone Number:	360 546-9726
Support Person:	Janet DeWitt	Phone: 546-9720
E-Mail:	morgan@vancouver.wsu.edu	FAX: 546-9038

Psych 372: Physiological Psychology Syllabus

Lecture notes for Psych 372: Physiological Psychology notes

Psych 401:Historical Development of Psychololgy

Links to Graduate Programs

Neuroscience

Return to WSU Vancouver Homepage

Research Interests

Neural Mechanisms of Pain Modulation and Morphine Tolerance

Pain messages traveling from the skin to the brain are subject to powerful modulation in the spinal cord. This modulation can occur by direct application of narcotics to the spinal cord or via descending messages from the brain. The primary descending system involved in pain modulation runs from the periaqueductal gray (PAG) to the rostral ventrolmedial medulla (RVM) to the spinal cord. Microinjection of opiates such as morphine into the PAG or RVM inhibit pain throughout the body. Our research is focused on understanding the function of the PAG and RVM, and how these structures contribute to tolerance to the pain inhibitory effects of morphine.

Although opiates are the most effective treatment for pain, morphine effectiveness is diminished by the development of tolerance with repeated administration. Our research has shown that the PAG plays an important role in this tolerance. Tolerance develops to microinjection of morphine into the ventrolateral, but not the lateral PAG or RVM. Blocking morphine binding in the PAG is sufficient to block the development of tolerance. Additional behavioral and electrophysiological studies indicate that opioid-sensitive GABAergic neurons are involved in morphine tolerance. Currently, we are examining the cellular mechanisms underlying morphine tolerance.

Research Team:

Colleague and co-PI: Dr. Susan Ingram

Erin Fossum--Head Research Technician

Aurora Lynch--Animal Care Technician

Tara Macey--Post-Doctoral Fellow

Paul Meyer--Post-Doctoral Fellow

Michelle Cyr—Psychology Graduate Student

Adie Wilson--Neuroscience Graduate Student

Undergraduate Assistants:

Elysia Beattie

Gavin Meyer

Edvinas Pocius

High School Assistants:

Dana Hong

Lauren Maher

Recent Publications:

Fossum, E. N., Lisowski, M. J., Macey, T. A., Ingran, S. L., & Morgan, M. M. (in press). Microinjection of the vehicle dimethyl sulfoxide (DMSO) into the periaqueductal gray modulates morphine antinociception. Brain Research

Loyd, D., Morgan, M.M., & Murphy, A.Z. (in press). Sexually dimorphic activation of the periaqueductal gray-Rostral ventromedial medullary circuit during the development of tolerance to morphine in the rat. European Journal of Neuroscience.

Ingram, S.L., Macey, T.A., Fossum, E.N., & Morgan, M.M. (in press). Increased potency of opioid agonists is associated with tolerance to repeated morphine administration. Neuropsychopharmacology.

Loyd, D., Morgan, M.M., & Murphy, A.Z. (2007). Morphine preferentially activates the periaqueductal gray – rostral ventromedial medullary pathway in the male rat: A potential mechanism for sex differences in antinociception. Neuroscience, 147(2):456-468.

Meyer, P.J., Fossum, E.N., Ingram, S.L., & Morgan, M.M. (2007). Analgesic tolerance to microinjection of the mu-opioid agonist DAMGO into the periaqueductal gray. Neuropharmacology, 52:1580-1585.

Ingram, S.L., Fossum, E.N., & Morgan, M.M. (2007). Behavioral and electrophysiological evidence for opioid tolerance in adolescent rats. Neuropsychopharmacology, 32(3):600-6.

Bernal, S.A., Morgan, M.M., & Craft, R.M. (2007). PAG mu opioid receptor activation underlies sex differences in morphine antinociception. Behav Brain Research, 177:126-133.

Morgan, M.M., Fossum, E.N., Levine, C.S., & Ingram, S.L. (2006). Antinociceptive tolerance revealed by cumulative intracranial microinjections of morphine into the periaqueductal gray in the rat. Pharmacology, Biochemistry & Behavior, 85(1):214-9

Ingram, S.L., Fossum, E.N., & Morgan, M.M. (2006). Behavioral and electrophysiological evidence for opioid tolerance in adolescent rats. Neuropsychopharmacology.

Morgan, M. M., Fossum, E. N., Stalding, B. M., & King, M. M. (2006). Morphine antinociceptive potency on chemical, mechanical, and thermal nociceptive tests in the rat. J. Pain, 7:358-366.

Morgan, M. M. & Ingram, S. L. (2006). The case for adopting policies to increase the participation of women in IASP. IASP Newsletter, Issue 1, pp. 3-5. (non-refereed).

Morgan, M. M., Tierney, B. W., & Ingram, S. L. (2005). Intermittent dosing prolongs tolerance to the antinociceptive effect of morphine microinjection into the periaqueductal gray. Brain Research, 1059:173-178.

Lane, D. A., Patel, P. A., & Morgan, M. M. (2005). Evidence for an intrinsic mechanism of antinociceptive tolerance within the ventrolateral Periaqueductal Gray of rats. Neuroscience, 135:227-234.

Morgan, M. M. & Clayton, C. C. (2005). Defensive behaviors evoked from the ventrolateral periaqueductal gray of the rat: Comparison of opioid and GABA disinhibition. Behav. Brain Research, 164:61-66.

Lane, D. A. & Morgan, M. M. (2005). Antinociceptive tolerance to morphine from repeated nociceptive testing in the rat. Brain Research, 1047:65-71.

Morgan, M. M., Clayton, C. C., & Boyer-Quick. J. S., &. (2005). Differential susceptibility of the PAG and RVM to tolerance to the antinociceptive effect of morphine in the rat. Pain, 113:91-98.

Current Grant Support:

Morgan, M. M. & Ingram, S. L. (co-P.I) National Institute on Drug Abuse. Cellular mechanisms of opioid tolerance. (RO1 DA015498). May, 2003 to April, 2008. $900,000 direct costs.

Ingram, S. L. & Morgan, M. M. Washington State University Alcohol and Drug Abuse. The Role of PAG Hyperexcitability in Morphine Tolerance. January, 2006 to June, 2007. $28,552.

Education:

Ph.D. in Physiological Psychology from UCLA, 1989.
Post-doctoral research in the Dept. of Neurology, UC, San Francisco, 1989 - 1993

Videos:

RVM Morphine Microinjection Video

PAG Morphine Microinjection Videos

PAG Saline

Lateral PAG morphine

Ventral PAG morphine

Photographs:

WSU Vancouver Psychology Colleagues

Mike in the Electrophysiology Lab