Figure 3. (a) Unusually high levels of spontaneous repetitive self grooming, in which the normal pattern of grooming behaviors are present but the bouts of grooming are strikingly prolonged, are measured over a 10-minute session in which the subject mouse is in an empty cage. Digital videos of the session are scored by an investigator uninformed of the genotype or treatment condition. Photograph by Dr Mu Yang, contributed by the author. (b) High levels of repetitive self-grooming are displayed by adult BTBR mice as compared with C57BL/6J mice. In this cross-fostering experiment, self-grooming scores in adults were found to be independent of the strain of the dam that raised the pup. Reproduced from ref 55: PankseppJB, Jochman KA, Kim JU, et al. Affiliative behavior, ultrasonic communication and social reward are influenced by genetic variation in adolescent mice. PLoS One. 2007;2:e351. Copyright Public Library of Science 2007.