https://academic.oup.com/pnasnexus/article/4/11/pgaf352/8314858

https://sj.jst.go.jp/news/202512/n1212-01k.html

Pain is a basic sensation associated with tissue injury and leads to facial expression. The facial images of free-moving mice with and without generation of pain were recorded and images subjected to train a convolutional neural network (CNN). The trained CNN successfully predicted the faces of AC-, capsaicin-, and calcitonin gene-related peptide-induced pain that had not been used for CNN training. It also detected the analgesic effect of diclofenac, a nonsteroidal anti-inflammatory drug, against AC-induced pain. The CNN focused on the head, forehead, ear, eye, cheek, and nose to predict pain or no pain.