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Facial grimacing is used to quantify spontaneous pain in mice and other mammals, but scoring relies on humans with different levels of proficiency. Here, we developed a cloud-based software platform called PainFace ( http://painface.net ) that uses machine learning to detect 4 facial action units of the mouse grimace scale (orbitals, nose, ears, whiskers) and score facial grimaces of black-coated C57BL/6 male and female mice on a 0 to 8 scale. Platform accuracy was validated in 2 different laboratories, with 3 conditions that evoke grimacing-laparotomy surgery, bilateral hindpaw injection of carrageenan, and intraplantar injection of formalin. PainFace can generate up to 1 grimace score per second from a standard 30 frames/s video, making it possible to quantify facial grimacing over time, and operates at a speed that scales with computing power. By analyzing the frequency distribution of grimace scores, we found that mice spent 7x more time in a "high grimace" state following laparotomy surgery relative to sham surgery controls. Our study shows that PainFace reproducibly quantifies facial grimaces indicative of nonevoked spontaneous pain and enables laboratories to standardize and scale-up facial grimace analyses.
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http://dx.doi.org/10.1097/j.pain.0000000000003187 | DOI Listing |
J Headache Pain
August 2025
Department of Neurology, Neurovascular Research Unit, Massachusetts General Hospital, 149 13th Street, Charlestown Rm 6.215, Boston, MA, 02129, USA.
Background: Spreading depolarization (SD) is the most likely cause of migraine aura and may be linked to trigeminal nociception. Using minimally invasive optogenetic SD induction (opto-SD), we previously showed that SD triggers acute periorbital mechanical allodynia-like behavior, supporting SD-induced activation of migraine-relevant trigeminal pain pathways. Here, we tested whether selective oral calcitonin gene-related peptide (CGRP) receptor antagonist, atogepant, could ameliorate SD-evoked pain and anxiety phenotypes.
View Article and Find Full Text PDFJ Neurosci
August 2025
Department of Oral & Maxillofacial Surgery, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78256
Temporomandibular disorder (TMD) significantly impairs the quality of life of patients due to chronic pain and limited jaw function. Many treatment options have been used such as pharmacologic management, physical therapy, oral appliance therapy, and surgery. However, effective treatment options remain limited.
View Article and Find Full Text PDFNeurosci Insights
July 2025
Department of Neuroscience, Jefferson Synaptic Biology Center, Vickie & Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, USA.
Development of neuropathic pain (NP) is one of the major complications associated with spinal cord injury (SCI). While well-established methods such as von Frey mechanical and facial grimace testing are often used to assess SCI-induced NP-like behaviors in animal models, these assays have significant limitations, including experimenter bias and long periods of active testing and analysis. To address these challenges, we aimed to develop a novel open field 2-texture preference test (TTPT) to assess NP-like behaviors following unilateral C5 hemicontusion SCI in mice.
View Article and Find Full Text PDFBone
July 2025
Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA; Richard L. Roudebush VA Medical Center, Indianapolis, IN, 46202, USA. Electronic address:
Impaired bone fracture healing can lead to chronic pain, loss of function, or life-long complications which can lead to limb-amputation. This study evaluated the effectiveness of human placental tissue-derived xenograft preparations (Connective Tissue Matrix, [CTM Biomedical®]) in promoting bone healing and reducing post-fracture pain behaviors using a preclinical, surgically induced, murine fracture model. CTM is thought to contain structural proteins and growth factors important for fracture healing.
View Article and Find Full Text PDFPain
July 2025
UNC Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
Neurokinin-1 (substance P) receptor (NK1R) antagonists failed to effectively treat pain in humans despite having antinociceptive properties in animals. Here, we sought to evaluate the efficacy of NK1R antagonist CP-99994 at reducing facial grimacing in white-coated CD-1 mice after laparotomy surgery when compared to the analgesics carprofen and buprenorphine. To enable this investigation, we developed a machine learning algorithm to automatically score facial grimacing in white-coated mice using the PainFace software platform.
View Article and Find Full Text PDF