Take a look at the picture below. Can you guess which one represents the face of a mouse in pain?
In a recent article entitled “coding of facial expressions of pain in the laboratory mouse”, which was published in Nature this past May, Langford et al. developed a standardized behavioral coding system for murine pain which they termed the mouse grimace scale (MGS).
For more information on the study and to find the answer to the trivia question above checkout the Neuroskeptic blog (which also has some other great posts as well so be sure to browse around while you’re there).