What is Allodynia and which neurons are responsible for its propagation?
Allodynia is the perception of stimuli that are usually painless as painful.
The authors of this study were able to identify neuronal groups in the spinal cord involved in this sensitization process.
They used a molecule from chili peppers called capsaicin, applied to the skin resulting in allodynia that extends to a broad region beyond the application site.
Warwick et al. were able to differentiate neuronal groups involved in pain transmission that responded directly to the application of the painful stimulus (capsaicin), from those neurons that later responded to non-painful stimuli, such as a light touch on the skin.
Interestingly, some of these neurons showed increased receptive field sizes, consistent with allodynia spreading beyond the capsaicin injection site.
These data help to better understand the processes of pain sensitization and the role of the spinal cord in them.
Charles Warwick, Joseph Salsovic, Junichi Hachisuka, Kelly M. Smith, Tayler D. Sheahan, Haichao Chen, James Ibinson, H. Richard Koerber & Sarah E. Ross.