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Cycle of Fear and Pain. From Raymond A. Dionne, Pain Control in Dentistry: The Basis for Rational Therapy. Compendium of Continuing Education in Dentistry v. 6 (1985): 16.

Edward Driscoll. Photograph courtesy of NIDCR Public Information Office.

The Gate Control Model - Reprinted by permission - Ronald Melzack and Patrick Wall, Pain mechanisms: a new theory. Science v. 150 (1965): 975. Copyright AAAS, shttp://www.sciencemag.org

Seymour Kreshover. Photograph courtesy of NIDCR Public Information Office.

Patrick Wall [L] and Ronald Melzack [R]. Photograph courtesy of Dr. Ronald Melzack.

Ron Dubner [L] and Barry Sessle [R] with colleague Eigild Moller at International Association for Dental Research, mid-1970s. Photograph courtesy of Dr. Barry Sessle.

The Neurobiology and Anesthesiology Branch, 1979. Photograph courtesy of M.A. Ruda.

Program for the International Symposium on Pain, Issaquah, Washington, May 1973. Courtesy of the International Association for the Study of Pain Records, Ms. Coll. 124, John C. Liebeskind History of Pain Collection, UCLA.

Aaron Ganz, Edward Driscoll, John Bonica, and Seymour Kreshover at Issaquah, 1973. Photograph courtesy of Louisa Jones.

John Bonica at the podium. Courtesy of the John J. Bonica Papers, MS. Coll. 118, John C. Liebeskind History of Pain Collection, UCLA.

Task-related responses of monkey medullary dorsal horn neurons. Journal of Neurophysiology v. 57 (1987): 292. Illustrations courtesy of Gary H. Duncan, M. Catherine Bushnell, Renee Bates, and Ronald Dubner.

Ronald Dubner, mid 1970s. Photograph courtesy of NIDCR Public Information Office.

Apparatus built by Fred Brown to administer thermal stimuli and record nerve impulses. Photograph courtesy of Marcia Meldrum.

Both Nociceptive-Specific neurons and Wide-Dynamic-Range neurons increase their rates of firing as the intensity of the pain stimulus (the hot pot) increases. Wide-dynamic-range neurons, however, show an accelerated increase in firing rate; these neurons are the most sensitive to changes in stimulus intensity. Drawing and Graph by Donald Bliss.

Differential Descriptor Scale. Adapted from Richard Gracely, Patricia McGrath, and Ronald Dubner, Ratio scales of sensory and affective verbal pain descriptors. Pain v. 5 (1978): 14.

Cross-modality matching of verbal descriptiors against noxious stimuli. From Richard Gracely, Ronald Budner, Patricia McGrath, and Marc Heft New methods of pain measurement and their application to control. International Dental Journal v. 28 (1978): 55, 59.

Rick Gracely at the computer Photograph courtesy of NIDCR Public Information Office.

The inflammatory cascade of chemical activity in response to tissue injury. From Raymond Dionne and Sharon Gordon, Prevention of Pain. Compendium of Continuing Education in Dentistry v. 18 (1997): 244.

The suppression of postoperative pain with NSAID (flurbiprofen) and a long-acting local anesthetic (etidocaine). From Raymond Dionne, New approaches to preventing and treating postoperative pain. Journal of the American Dental Association v. 123 (1992): 29.

Raymond Dionne conducting trial. Photograph courtesy of NIDCR Public Information Office.

Mitchell Max. Photograph courtesy of NIDCR Public Information Office.

Development of "excitotoxicity" in response to ongoing pain signals from an injured nerve. Illustration by Donald Bliss, adapted from: Richard Gracely, Susan Lynch, and Gary Bennett, Painful neuropathy: altered central processing maintained dynamically by peripheral input. Pain v. 51 (1992): 188.

A World War II causalgia patient. Photograph reprinted by permission from F. H. Mayfield and J. W. Devine, Causalgia. Surgery, Gynecology and Obstetrics v. 80 (1945): 631-635.

A rat guarding its paw. Photograph courtesy of Richard Gracely.

Gary Bennett. Photograph courtesy of American Pain Society.

Distribution of chemical messengers within axons descending from the brain (blue), primary afferent fibers transmitting from skin and tissues (pink), and intrinsic "relay" neurons. Illustration courtesy of M.A. Ruda.

Ron Dubner and M.A. Ruda in the lab, late 1970s. Photograph courtesy of NIDCR Public Information Office.

Three different types of neurons within the dorsal horn of the spinal cord. Drawing by Donald Bliss.

The enhancosome: twin phosphorylation and dephosphorylation reactions of promoter genes CREB and TATA regulate the transcription of dynorphin. Illustration courtesy of Michael Iadarola.

Dynorphin synthesis in rat spinal cord cells receiving input from the inflamed hindlimb v. spinal cord cells receiving input from contralateral limb. From M. A. Ruda, M. J. Iadarola, L. V. Cohen, and W. S. Young III, In situ hybridization histochemistry and immunocytochemistry reveal an increase in spinal dynorphin biosynthesis in a rat model of peripheral inflammation and hyperalgesia. Proceedings of the National Academy of Sciences v. 85 (1988): 623.

M.A. Ruda, mid-1990s. Photograph courtesy of NIDCR Public Information Office.

Michael Iadarola with visitors to the laboratory, mid-1990s. Photograph courtesy of NIDCR Public Information Office.

The Pain Research at NIDCR on-line exhibit was created by Marcia Meldrum , PhD, 1998-1999 DeWitt Stetten, Jr., Memorial Fellow in the History of Biomedical Sciences and Technology, and designed by Mary Colella (IITRI) with the help of Dianne Gannon (IITRI). Cover illustration by Betty Hebb of the Medical Arts and Photography Branch, NIH.