Fig. 5.

Pruritogen-responsive STT neurons are a subset of nociceptive STT neurons. A: peristimulus time histogram showing time course of response to histamine (n = 15), cowhage (n = 11), and capsaicin (n = 18) in pruriceptive STT neurons. The discharge from capsaicin was significantly greater than the discharge from either histamine or cowhage (***P < 0.001, 2-ANOVA), which were not different from each other. B and C: area of each circle is proportional to the size of each STT subpopulation indicated. Of the total STT population nociceptive-only cells represent 67%, histamine+ represent 20%, and cowhage+ represent 13%. Pie charts indicate % of STT neurons from each subpopulation that were responsive to a 50°C heat ramp (B) or capsaicin (C) (**P < 0.01, Fisher's exact test).