1. Experimental behaviour testing: pain
S. Savage, D. Ma 
British Journal of Anaesthesia 
Volume 114, Issue 5, Pages (May 2015)
DOI: /bja/aeu346
Copyright © 2015 The Author(s) Terms and Conditions

2. Fig 1
The organization of the nociceptive testing. Highlighted are the various systems each pain test targets. Simple tests such as the von Frey test affect the periphery via spinal cord feedback, while higher cognitive tests such as conditioned place preference (CPP) utilize more complex circuitry in the brain, based on nociceptive or analgesic feedback from lower centres. The formalin test has a two-phased reaction, initially causing pain and inflammation at the peripheral site of injection, while later causing central sensitization, particularly in the spinal cord.
British Journal of Anaesthesia  , DOI: ( /bja/aeu346)
Copyright © 2015 The Author(s) Terms and Conditions