Nociception
Opioid Receptors: Overview
Analgesia and Pain Management
Opioid Analgesics: Morphine and Other Natural Cogeners
Opioid Analgesics: Synthetic and Semisynthetic Opioids
Pain
You might also read
Articles linked to this work by shared authors, journal, and citation graph.
Updated: Jul 26, 2026

Use of the Operant Orofacial Pain Assessment Device (OPAD) to Measure Changes in Nociceptive Behavior
Published on: June 10, 2013
K L Casey1, P Svensson, T J Morrow
1Department of Neurology, University of Michigan, Ann Arbor, Michigan 48109, USA.
Fentanyl (a mu-opioid receptor agonist) selectively reduces pain perception by suppressing brain responses to noxious cold, while leaving vibrotactile sensation unaffected. This indicates a targeted mechanism for opioid analgesia.
Area of Science:
Background:
Purpose of the Study:
Main Methods:
Main Results:
Conclusions: