Figure 1.

State-dependent sensory processing in the somatosensory system. (A) The basal sensitivity of the system is normally such that only a high-intensity C or Aδ stimulus produces pain. (B) C fiber inputs induce immediate posttranslational changes in the dorsal horn, resulting in central sensitization and altering basal sensitivity such that low intensity stimuli result in pain. (C) Conditioning C fiber strength inputs induce activity-dependent transcriptional changes in the DRG and dorsal horn, resulting in a potentiated system augmenting responsiveness to subsequent C fiber inputs. (D) Inflammation results in both a potentiated system and phenotypic switches such that both C fiber and low-intensity Aβ fiber inputs can evoke central sensitization.