Fin injury in vivo produces short- and long-term sensitization of mechanoafferents and SA in the fin nerve. Fin injury in vivo produces short- and long-term sensitization of mechanoafferents and SA in the fin nerve. A, In vivo fin crush 30 min before excision sensitized mechanoafferents in the injured and contralateral fins. Activity evoked by 10 g tests showed increases at medial and caudal sites. B, In vivo fin crush 24 h before excision caused long-term sensitization of mechanosensory afferents in crushed and contralateral fins. C, In vivo but not ex vivo fin crush increased SA. The injured fin showed significantly higher SA 45 min after in vivo crush, whereas the injured and contralateral fins showed higher rates 24 h after in vivo crush. D, SA and activity evoked by tactile stimulation in fins from animals with natural injuries (received during interactions with conspecifics during the preceding 24 h) showed changes similar to those in experimentally injured animals. *p < 0.05, **p < 0.01. Robyn J. Crook et al. J. Neurosci. 2013;33:10021-10026 ©2013 by Society for Neuroscience